DNV-OS-C502: Offshore Concrete StructuresDET NORSKE VERITAS AS Offshore Standard DNV-OS-C502,...

OFFSHORE STANDARD

The electronic p

DNV-OS-C502

Offshore Concrete StructuresSEPTEMBER 2012

DET NORSKE VERITAS AS

df version of this document found through httpwwwdnvcom is the officially binding version

FOREWORD

DNV is a global provider of knowledge for managing risk Today safe and responsible business conduct is both a licenseto operate and a competitive advantage Our core competence is to identify assess and advise on risk management Fromour leading position in certification classification verification and training we develop and apply standards and bestpractices This helps our customers safely and responsibly improve their business performance DNV is an independentorganisation with dedicated risk professionals in more than 100 countries with the purpose of safeguarding life propertyand the environment

DNV service documents consist of among others the following types of documentsmdash Service Specifications Procedural requirementsmdash Standards Technical requirementsmdash Recommended Practices Guidance

The Standards and Recommended Practices are offered within the following areasA) Qualification Quality and Safety MethodologyB) Materials TechnologyC) StructuresD) SystemsE) Special FacilitiesF) Pipelines and RisersG) Asset OperationH) Marine OperationsJ) Cleaner EnergyO) Subsea SystemsU) Unconventional Oil amp Gas

copy Det Norske Veritas AS September 2012

Any comments may be sent by e-mail to rulesdnvcom

This service document has been prepared based on available knowledge technology andor information at the time of issuance of this document and is believed to reflect the best ofcontemporary technology The use of this document by others than DNV is at the users sole risk DNV does not accept any liability or responsibility for loss or damages resulting fromany use of this document

Offshore Standard DNV-OS-C502 September 2012Changes ndash Page 3

CHANGES

GeneralThis document supersedes DNV-OS-C502 October 2010

Text affected by the main changes in this edition is highlighted in red colour However if the changes involvea whole chapter section or sub-section normally only the title will be in red colour

Main changes

bull Generalmdash Sections 1 2 3 7 and 8 have minor changes onlymdash Previous Appendix D ldquoSeismic Analysis (Guidelines)rdquo is deleted but included in Section 5mdash Previous Appendices E is new Appendix Dmdash Previous Appendices F is new Appendix Emdash Appendices A B C D and E have minor changes onlymdash Appendices F G H and I are new

bull Sec4 Materialsmdash Rearranged text based on the old DNV-OS-C502 but including the new materials The design strength

values have been moved from Section 6 to this Section 4 The new materials are structural grout fibrereinforced structural grout fibre reinforced concrete and fibre reinforced rods (FRP bars) replacing steelreinforcement as reinforcement in concrete structures

bull Sec5 Loads and Analyses Requirements mdash Section is reworked completely and harmonized with reference to ISO19903 Load factors are included in

this section It shall be noted that for FRP reinforced members two new load combinations are introducedThese new load combinations take into account the different material factors required for long term- andshort term loading

bull Sect6 Detailed Design of Offshore Concrete Structures mdash Section is reworded and rearrangedmdash Material factors to be included in design are shown For FRP bars the material factors to be used in design

shall be determined from tests and included in the Material Certificate The material factor for FRP willdepend on the duration of loading caused by creep fracture

mdash The section is changed by including design approach for the new materials covered by the standardmdash The section is also modified to ensure liquid tightness for oil storage containment structures following

extreme waves earthquake or collision loads

bull Sec9 Certification and Classification mdash This new section has been added to provide details of DNVs services relating to the application of this

standard Notably certification schemes for FRP bars and Structural Grout are detailed

Corrections and ClarificationsIn addition to above stated main changes a number of corrections and clarifications may have been made tothe existing text

Offshore Standard DNV-OS-C502 September 2012 Contents ndash Page 4

CONTENTS

Sec 1 Introduction 12

A General 12A 100 Introduction 12A 200 Objective 12A 300 Scope and applications 12A 400 Codes and standards other than DNV standard 13A 500 Classification 13A 600 Certification 13

B References 13B 100 General 13B 200 Normative references 13B 300 Informative references 14

C Definitions 15C 100 Verbal forms 15C 200 Terms 15C 300 Terms (continued) 19

D Abbreviations and Symbols 20D 100 Abbreviations 20D 200 Symbols 21

Sec 2 Safety Philosophy 26

A General 26A 100 Objective 26A 200 Systematic review 26A 300 Safety class methodology 26A 400 Quality assurance 27A 500 Health safety and environment 27A 600 Qualifications of personnel 27

B Design Format 27B 100 General 27

C Identification of Major Accidental Hazards 28C 100 General 28

D Life extensions 29D 100 General 29

Sec 3 Design Documentation 30

A General 30A 100 Introduction 30A 200 Overall Planning 30A 300 Documentation required in the planning stage 30A 400 Documentations required prior to construction 32A 500 ldquoAS-BUILTrdquo documentation 33A 600 Inspectionmonitoring plans for structure in service 33

Sec 4 Materials 34

A General 34A 100 General 34

B ConcreteGrout Constituents 34B 100 General 34B 200 Cement 34B 300 Mixing water 35B 400 Normal weight aggregates 36B 500 Lightweight aggregates 36B 600 Additions 36B 700 Admixtures 37

C Concrete 37C 100 Concrete categorization 37C 200 Concrete mix 37C 300 Concrete characteristic strength 38

D Fibre Reinforced Concrete 41D 100 Material requirements of fibre reinforced concrete 41

E Structural Grout 43E 100 Material requirements 43E 200 Pre-packed blended grout 45

F Fibre Reinforced Structural Grout 45F 100 Material requirements for fibre reinforced structural grout 45F 200 Pre-packed blended grout with fibres 47

G Steel Reinforcement 47G 100 General 47G 200 Mechanical splices and end anchorages for reinforcement 47G 300 Approval of welding procedures 48G 400 Steel reinforcement characteristic strength 48

H Steel Prestressing Reinforcement 48H 100 General 48H 200 Components for the prestressing system 48H 300 Steel prestressing reinforcement characteristic strength 48

I FRP Reinforcement 48I 100 General 48I 200 Mechanical splices and anchorages for FRP reinforcements 49I 300 FRP prestressed bars 49I 400 FRP reinforcement characteristic strength 49

J Steel Fibres 50J 100 General 50

K FRP Fibres 50K 100 General 50

L Embedded Materials 50L 100 General 50

M Other Materials 50M 100 Repair materials 50M 200 Non-cementitious materials 50M 300 Equivalent materials 51

N Testing of Materials 51N 100 Testing of freshly mixed concrete 51N 200 Testing of concrete in the structure 51N 300 Grout for prestressing tendons 51N 400 Pre-packed blended grout 51N 500 Reinforcement steel 51N 600 Prestressing steel 51N 700 Mechanical splices for reinforcement 51N 800 Components for the prestressing system 51N 900 Welding procedures 51N 1000 Testing of repair materials 51N 1100 Testing of FRP materials 51

Sec 5 Loads and Analyses Requirements 52

A Requirements to Design 52A 100 General 52A 200 Site related functional requirements and environmental considerations 52A 300 Facility operational requirements 52A 400 Structural requirements 52A 500 Materials requirements 53A 600 Execution requirements 53A 700 Temporary phases requirements 53

B Design principles 53B 100 General 53B 200 Design loads 54B 300 Design resistance 54

C Load and Load Effects 54C 100 General 54C 200 Environmental loads 55C 300 Functional loads 56C 400 Accidental loads 56

D Load Combinations and Partial Safety Factors 58D 100 Partial load factors γf 58D 200 Combinations of loads 60D 300 Consequence of failure 60

E Structural Analysis 60E 100 General 60E 200 Youngrsquos modulus to be used in load effect analyses 62E 300 Effects of temperature shrinkage creep and relaxation 63E 400 Special load effects 64E 500 Physical representation 64E 600 Loads 65E 700 Mass simulation 65E 800 Damping 65E 900 Linear elastic static analysis 65E 1000 Dynamic analysis 65E 1100 Pseudo-static analysis 65E 1200 Non-linear analysis 65E 1300 Probabilistic analysis 65E 1400 Reliability analysis 66E 1500 Analyses requirements 66E 1600 Analysis of construction stages 66E 1700 Transportation analysis 66E 1800 Installation and deck mating analysis 67E 1900 In-service strength and serviceability analyses 67E 2000 Fatigue analysis 67E 2100 Seismic analysis 67E 2200 Accidental and overload analyses 67E 2300 Platform removalreuse 68

F Topside Interface Design 68F 100 Introduction 68F 200 Basis for design 68F 300 Deckshaft structural connection 69F 400 Topsides - substructures mating 69F 500 Transportation 69

G Barges 69G 100 General 69

Sec 6 Detailed Design of Offshore Concrete Structures 70

A General 70A 100 Introduction 70A 200 Material 70A 300 Load effects 70A 400 Effective flange width 70A 500 Composite structures 71A 600 Prestressed structures with unbonded tendons 71A 700 Yield line theory 72

B Design Principles 72B 100 General 72B 200 Limit states 72B 300 Characteristic values for material strength 73B 400 Partial safety factors for materials 73B 500 Design by testing 73

C Basis for Design by Calculation 73C 100 Design material strength 73C 200 Stress strain curve for structural grout and fibre reinforced grout 79C 300 Steel reinforcement stress ndash strain curves 79C 400 FRP reinforcement stress ndash strain curves 80C 500 Geometrical dimensions in the calculation of sectional capacities 80C 600 Tension in structural members 81C 700 Creep effects 81C 800 Effect of water pressure 81

D Bending Moment and Axial Force (ULS) 81D 100 General 81

E Slender Structural Members 82E 100 General 82

F Shear Forces in Beams and Slabs 84F 100 Basis 84F 200 Simplified method 85F 300 Truss model method 87F 400 Additional force in the longitudinal reinforcement from shear force 87F 500 Slabs subjected to concentrated actions 88

G Torsional Moments in Beams 90G 100 General 90

H General Design Method for Structural Members Subjected to In-plane Forces 91H 100 General 91H 200 Membrane (in-plane) shear resistance 92

I Regions with Discontinuity in Geometry or Loads 94I 100 General 94

J Shear Forces in Construction Joints 94J 100 General 94

K Bond Strength and Anchorage Failure 95K 100 General 95

L Partially Loaded Areas 100L 100 General 100

M Fatigue Limit State 102M 100 General 102M 200 Fatigue strength design life 103M 300 Bending moment and axial force 104M 400 Shear force 105M 500 Anchorage and splicing 105

N Accidental Limit State 106N 100 General 106N 200 Explosion and impact 106N 300 Fire 106

O Serviceability Limit State 107O 100 General 107O 200 Durability 107O 300 Crack width limitations 108O 400 Displacements 109O 500 Vibrations 110O 600 Tightness against leakages of fluids 110O 700 Tightness against leakage of gas 110O 800 Crack width calculation 110O 900 Limitation of stresses in prestressed structures 112O 1000 Freezethaw cycles 112O 1100 Temperature effects 112O 1200 Deflection prediction for FRP reinforced concrete members 112

P Design by Testing 113P 100 General 113P 200 The test specimen 113P 300 Design actions 113P 400 Test procedure 113P 500 Processing of the test results 114P 600 Test report 114

Q Rules for Detailing of Reinforcement 115Q 100 Positioning 115Q 200 Concrete cover 115Q 300 Splicing 116Q 400 Bending of steel reinforcing bars 117Q 500 Bending of FRP bars 118Q 600 Minimum area of reinforcement - General 118Q 700 Minimum area of reinforcement - slabsplates 118Q 800 Minimum area of reinforcement - flat slabs 119Q 900 Minimum area of reinforcement - beams 120Q 1000 Minimum area of reinforcement - columns 121Q 1100 Minimum area of reinforcement - walls 122Q 1200 Minimum area of reinforcement - reinforced foundations 123Q 1300 Minimum area of reinforcement - prestressed structures 123

R Corrosion Control 123R 100 General 123R 200 Corrosion zones and environmental parameters 124R 300 Forms of corrosion and associated corrosion rates 124R 400 Cathodic protection 124

S Design of Fibre Reinforced Concrete Members 125S 100 General 125

T Design of Structural Members made of Grout 125T 100 General 125T 200 Design for strength in ULS and ALS 126T 300 Design for fatigue life 126T 400 FE Analyses of grouted connections 127T 500 Fibre reinforced grout 127T 600 Type A steel to steel connections with grout 127T 700 Type B steel to concrete connection 128T 800 Type C concrete to concrete connection 128T 900 Type D connecting two precast concrete elements with in-situ cast structural grout connection 129

Sec 7 Construction 130

A General 130A 100 Application 130A 200 Codes and standards 130A 300 Scope 130

B Definitions 130B 100 Terms 130

C Documentation 130C 100 General 130

D Quality Control - Inspection Testing and Corrective Actions 130D 100 General 130D 200 Inspection Classes 131D 300 Inspection of materials and products 131D 400 Inspection of execution 131

E Construction Planning 133E 100 General 133

F Materials and Material Testing 134F 100 General 134F 200 Constituent Materials 134F 300 Reinforcement and prestressing system components 135F 400 Production and on-site quality control testing 136F 500 Testing of concrete in the structure 137F 600 Non-cementitious materials 137

G Formwork 137G 100 Design materials and erection 137G 200 Slip-form systems 138G 300 Jump-forming systems 138G 400 Inserts in formwork recesses and blockouts 138G 500 Removal of formwork and falsework 139G 600 Surface treatment and final preparation 139

H Reinforcement and Embedded Steel 139H 100 Reinforcement 139H 200 Prestressing ducts and anchorages 140H 300 Embedded steel 141H 400 Inspection and survey 141

I Production of Concrete and Grout 142I 100 General 142

J Transport Casting Compaction and Curing of Concrete 142J 100 Transport 142J 200 Casting and compaction 143J 300 Curing 144J 400 Completion 144

K Completion of Prestressing Systems 145K 100 Threading and stressing of tendons 145K 200 Tensioning of tendons 145

K 300 Pre-tensioning 145K 400 Post-tensioning 146K 500 Protective measures grouting greasing concreting 146K 600 Unbonded tendons 146K 700 Grouting of ducts 146K 800 Greasing operations 147

L Repairs 147L 100 General 147

M Corrosion Protection 147M 100 General 147

N Site Records and As-built Documentation 147N 100 General 147

O Precast Concrete Elements 148O 100 General 148O 200 Handling and storage 148O 300 Placing and adjustment 148O 400 Jointing and completion works 148

P Geometrical Tolerances 149P 100 General 149P 200 Reference system 149P 300 Member tolerances (Guidelines) 149P 400 Cross-sectional tolerances (Guidelines) 150P 500 Embedments and penetrations (Guidelines) 150

Q Grouting Operations 151Q 100 General 151

Sec 8 In-service Inspection Maintenance and Conditional Monitoring 152

A General 152A 100 Application 152A 200 Scope 152A 300 Personnel qualifications 152A 400 Planning 152A 500 Programme for inspection and condition monitoring 153A 600 Inspection and condition monitoring milestones and intervals 153A 700 Documentation 153A 800 Important items related to inspection and condition monitoring 154A 900 Corrosion protection 155A 1000 Inspection and condition monitoring types 156A 1100 Marking 156A 1200 Guidance for inspection of special areas 156

Sec 9 Certification and Classification 159

A General 159A 100 Application 159A 200 Certification and classification principles 159A 300 Assumptions 159A 400 Documentation requirements 159A 500 Certificate types 159A 600 Requirements to Certification 160

B Classification of Offshore Structures 160B 100 General 160B 200 Materials 160B 300 Certification of materials 160

C Classification of Concrete Barges 161C 100 General 161C 200 Materials 161C 300 Certification of materials 161

D Certification of FRP Reinforcement (NV) 161D 100 General 161D 200 Material testing 161D 300 Manufacturing site approval 161D 400 Award of certificate 162D 500 Maintenance of certificate 162

E Certification of Structural Grout (NV) 162E 100 General 162E 200 Material testing 162E 300 Approval of supporting documentation and mock up testing 163E 400 Manufacturing site approval 163E 500 Award of certificate 164E 600 Maintenance of certificate 164

App A Environmental Loading (Guidelines) 165

A General 165A 100 Environmental Loads 165A 200 Extreme wave loads 165A 300 Diffraction analysis 166A 400 Additional requirements for dynamic analysis under wave load 166A 500 Model testing 166A 600 Current load 167A 700 Wind loads 168

App B Structural Analyses ndash Modelling (Guidelines) 169

A General 169A 100 Physical representation 169A 200 Loads 170A 300 Mass simulation 171A 400 Damping 171

App C Structural Analyses (Guidelines) 172

A General 172A 100 Linear elastic static analysis 172A 200 Dynamic analysis 172A 300 Pseudo-static analysis 173A 400 Non-linear analysis 173

App D Use of Alternative Detailed Design Standard (Guidelines) 175

A General 175A 100 Introduction 175A 200 Conditions 175

App E Crack width Calculation (Guidelines) 177

A Steel reinforced structures 177A 100 Introduction 177A 200 Stabilized crack pattern 177A 300 Distance between cracks with deviations between the principle strain directions and the direction of the

reinforcement 178A 400 General Method 178A 500 Simplified Approach 178

B FRP reinforced structures 178

App F Requirements to Content in Material Certificates for FRP Bars 181

A General 181A 100 Minimum requirements 181

B Testing of Materials 182B 100 Recommended testing 182B 200 Requirements of testing 182

App G QAQC System for Manufacture of FRP Bars (Guidelines) 184

A General 184A 100 Minimum documentation 184A 200 Physical properties of bars 186

App H Requirements to Content in Material Certificate for Structural Grout 188

B Testing of Materials 189B 100 Recommended testing 189

B 200 Requirements of testing 191

C Supporting Documentation 192C 100 Minimum requirements 192

App I QAQC System for Manufacture of Structural Grout or Equivalent Material (Guidelines) 194

Offshore Standard DNV-OS-C502 September 2012 Sec1 ndash Page 12

SECTION 1INTRODUCTION

A General

A 100 Introduction101 This offshore standard provides principles technical requirements and guidelines for the designconstruction and in service inspection of Offshore Concrete Structures The Concrete Structures may befloating or ground supported structures102 This standard shall be used together with the general offshore design standards for steel structures DNV-OS-C101 DNV-OS-C102 DNV-OS-C103 DNV-OS-C105 and DNV-OS-C106 These standards cover awide range of different structures103 The standard covers design fabricationconstruction installation and inspection of Offshore ConcreteStructures104 For design and construction of offshore concrete wind turbines reference is made to DNV-OS-J101ldquoDesign of Offshore Wind Turbines Structuresrdquo105 For design and construction of LNG terminal structures and containment systems reference is made toDNV-OS-C503 ldquoConcrete LNG Terminal Structures and Containment Systemsrdquo106 This standard covers design of fixed and floating platformsstructures for oil production and oil storageand barges where reinforced and prestressed concrete is used as structural material107 To provide manufacturers which are currently supplying grouts for DNV Certified andor Verifiedprojects time to attain certification for their products the requirements included here-in for MaterialCertificates for grout and equivalent materials shall not come into effect until 1st January 2014

A 200 Objective201 The objectives of this standard are to

mdash Provide an international standard for the design construction and in-service inspection of OffshoreConcrete Structures with an acceptable level of safety by defining minimum requirements for designconstruction control and in-service inspection

mdash Serve as a contractual reference document between supplier and purchasers related to design constructionand in-service inspection

mdash Serve as a guideline for designer supplier purchasers and regulators

A 300 Scope and applications301 The standard is applicable to design construction inspection and maintenance of Offshore ConcreteStructures using structural concrete and reinforcement as defined in Section 4 as the structural material in thesupport structure as defined in 302 below302 The standard can be used in the structural design of the following types of support structures which arereferred in this standard as Offshore Concrete Structures

mdash Gravity Based Structures (GBS) for oilgas production offshoremdash GBS for oilgas production with oil storage facilitymdash GBS for offshore and onshore wind turbine foundationsmdash Floating concrete structures for production of oilgas The structure may be of any type floating structure

ie Tension leg platform (TLP) column stabilised units and barge type unitsmdash Deep water caisson type concrete foundation of bridgesmdash Floating foundations for bridges parking houses or storage buildings

303 Appendices A to E contain guidelines for the design of Offshore Concrete Structures304 Floating Offshore Concrete Structures shall be designed with freeboard and intact stability in accordancewith DNV-OS-C301 For temporary phases the stability shall be in accordance with DNV Rules for Planningand Execution of Marine Operations305 The development and design of new concepts for Offshore Concrete Structures requires a systematichazard identification process in order to mitigate the risk to an acceptable risk level Hazard identification istherefore a central tool in this standard for this purpose306 Appendix F contains requirements for the contents of the Material Certificate for FRP bars307 Appendix G contains QAQC system for manufacture of FRP bars308 Appendix H contains requirements for the Material Certificate of structural grout and fibre reinforcedstructural grout

309 Appendix I contains QAQC system for manufacture of structural grout and fibre reinforced structuralgrout

A 400 Codes and standards other than DNV standard

401 In case of conflict between the requirements of DNV standard and a reference document other than DNVstandard the requirement of DNV standard shall prevail

402 The provision for using codes or standards other than DNV is that the same safety level as provided bythis DNV standard is obtained

403 Where reference is made to codes and standards other than DNV the valid revision shall be taken as therevision which is current at the date of issue of this standard unless otherwise noted

404 In addition to the requirements mentioned in this standard it is also the responsibility of the designerowner and operator to comply with additional requirements that may be imposed by the flag state or the coastalstate or any other jurisdictions in the intended area of deployment and operation

A 500 Classification

501 Classification principles procedures and application of class notations related to classification servicesof offshore units are specified in the DNV Offshore Service Specifications given in Table A1

502 See Section 9 for details of DNV services with regard to the classification of Concrete Barges

A 600 Certification

601 See Section 9 for details of DNV services

B References

B 100 General

101 In this standard when dated references are presented only the edition cited applies For undatedreferences the latest edition of the referenced document (including amendments) applies

B 200 Normative references

201 The standards in Table B1 include provisions which through reference in this text constitute provisionsof this standard

Table A1 DNV Offshore Service SpecificationsReference Title

DNV-OSS-101 Rules for Classification of Offshore Drilling and Support Units DNV-OSS-102 Rules for Classification of Floating Production and Storage UnitsDNV-OSS-103 Rules for Classification of LNGLPG Floating Production and Storage Units or InstallationsDNV-OSS-121 Classification Based on Performance Criteria Determined by Risk Assessment MethodologyDNV-OSS-304 Risk Based Verification of Offshore StructuresDNV-OSS-309 Verification certification and classification of gas export and receiving terminalsDNV-OSS-401 Technology Qualification Management

Table B1 DNV Rules and Offshore StandardsReference Title

DNV Rules Rules for Classification of Ships Pt5 Ch7 Sec14 ldquoConcrete BargesrdquoDNV Rules DNV Rules for Planning and Execution of Marine OperationsDNV-OS-A101 Safety Principles and ArrangementDNV-OS-C101 Design of Offshore Steel Structures General (LRFD Method)DNV-OS-C102 Structural Design of Offshore ShipsDNV-OS-C103 Structural Design of Column-stabilised Units (LRFD method)DNV-OS-C105 Structural Design of TLPS (LRFD method)DNV-OS-C106 Structural Design of Deep Draught Floating UnitsSpars (LRFD and WSD Method)DNV-OS-C301 Stability and Watertight IntegrityDNV-OS-C503 Concrete LNG Terminal Structures and Containment SystemsDNV-OS-J101 Design of Offshore Wind Turbine Structures

B 300 Informative references

301 The latest valid revision of the documents in Table B2 Table B3 and Table B4 apply These includeacceptable methods for fulfilling the requirements in this standard See also current DNV List of Publications

302 Other recognised codes or standards may be applied provided it is documented that they meet or exceedthe level of safety of this DNV Offshore Standard reference is made to Appendix D

Table B2 DNV Rules and Offshore Object Standards for Structural DesignReference Title

DNV Rules Rules for Classification of Ships Pt5 Ch5 ldquoLiquefied Gas CarriersrdquoDNV-OS-B101 Metallic MaterialsDNV-OS-C401 Fabrication and Testing of Offshore StructuresDNV-OS-E301 Position MooringDNV-OS-J102 Offshore Substations for Wind Farms

Table B3 DNV Recommended Practices and Classification NotesReference Title

DNV-RP-C201 Buckling Strength of Plated StructuresDNV-RP-C202 Buckling Strength of ShellsDNV-RP-C203 Fatigue Strength Analysis of Offshore Steel StructuresDNV-RP-C205 Environmental Conditions and Environmental LoadsDNV-RP-E301 Design and Installation of Fluke Anchors in ClayDNV-RP-E302 Design and Installation of Plate Anchors in ClayClassification Note 301 Buckling Strength Analysis of Bars and Frames and Spherical Shells Section 2 Bars and

FramesClassification Note 304 FoundationsClassification Note 306 Structural Reliability Analysis of Marine StructuresClassification Note 307 Fatigue Assessments of Ship Structures

Table B4 Other referencesReference Title

ACI 4401R-06 Guide for the design and construction of structural concrete reinforced with FRP barsACI 4403R-04 Guide test methods for fibre-reinforced polymers (FRPs) for reinforcing or strengthening concrete

structuresACI 440-4R ndash 04 Prestressing Concrete Structures with FRP TendonsACI 440R-07 Report on fibre-reinforced polymer (FRP) reinforcement for concrete structures ASTM C150 Standard Specification for Portland CementASTM C157 Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and ConcreteASTM C191 Standard Test method for Time of Setting of Hydraulic Cement by Vicat NeedleASTM C230 Standard Specification for Flow Table for Use in Tests of Hydraulic CementASTM C348 Standard Test Method for Flexural Strength of Hydraulic Cement MortarsASTM C403 Standard Test Method for Time of Setting of Concrete Mixtures by Penetration ResistanceASTM C457 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in

Hardened ConcreteASTM C469 Standard Test Method for Static Modulus of Elasticity and Poissons Ratio of Concrete in

CompressionASTM C490 Standard Practice for Use of Apparatus for the Determination of Length Change of Hardened

Cement Paste Mortar and ConcreteASTM C512 Standard Test Method for Creep of Concrete in CompressionASTM C940 Standard Test Method for Expansion and Bleeding of Freshly Mixed Grouts for Preplaced-

Aggregate Concrete in the LaboratoryCSA S806-12 Design and construction of building structures with fibre-reinforced polymersEN 12350-6 Testing fresh concrete - Part 6 Density EN 12350-7 Testing fresh concrete - Part 7 Air content - pressure methodsEN 12350-8 Testing fresh concrete - Part 8 Self-compacting concrete - Slump flow testEN 12390-3 Testing hardened concrete - Part 3 Compressive strength of test specimens EN 12390-7 Testing hardened concrete - Part 7 Density of hardened concrete

C Definitions

C 100 Verbal forms101 Shall Indicates a mandatory requirement to be followed for fulfilment or compliance with the presentstandard Deviations are not permitted unless formally and rigorously justified and accepted by all relevantcontracting parties102 Should Indicates a recommendation that a certain course of action is preferred or particularly suitableAlternative courses of action are allowable under the standard where agreed between contracting parties butshall be justified and documented103 May Indicates a permission or an option which is permitted as part of conformance with the standard

C 200 Terms201 Abnormal Level Earthquake (ALE) Intense earthquake of abnormal severity under the action of whichthe structure should not suffer complete loss of integrity When exposed to the ALE a manned structure issupposed to maintain structural andor floating integrity for a sufficient period of time to enable evacuation totake place202 Accidental Limit States (ALS) Limit state related to the possibility of the structure to resist accidentalloads and maintain integrity and performance of the structure due to local damage or flooding203 Accidental loads (A) Rare occurrences of extreme environmental loads fire flooding explosionsdropped objects collisions unintended pressure differences leakage of LNG etc204 Aggregates Constituent material of concrete or grout added to increase volume weight or durability ofthe material Aggregates are the main constituent both with respect to volume and weight in a structuralconcrete mix They may generally be divided into two groups these being sand or fine aggregate (materialsless than 5 mm) and coarse aggregate (materials larger than 5 mm)205 Air gap Free distance between the 100 year design wave and the underside of a topside structuresupported on columns allowing the wave to pass under the topside structure When air gap is sufficiently largethen no wave pressure is applied to the topside structure206 AS-BUILT Documentation Documentation of the offshore structure as finally constructed Sec3 A500presents the list of documents that are part of the AS-BUILT documentation207 Atmospheric zone The external surfaces of the unit above the splash zone208 Cathodic protection A technique to prevent corrosion of a steel surface by making the surface to be thecathode of an electrochemical cell209 Cement Binder component in a structural concrete or grout mix210 Characteristic load The reference value of a load to be used in the determination of load effects Thecharacteristic load is normally based upon a defined fractile in the upper end of the distribution function forload211 Characteristic material strength The nominal value of material strength to be used in the determinationof the design resistance The characteristic material strength is normally based upon a 5 fractile in the lowerend of the distribution function for material strength

EN 196-1 Methods of testing cement - Part 1 Determination of strength EN 196-3 Methods of testing cement - Part 3 Determination of setting times and soundness ISO 1920-4 Testing of concrete -- Part 4 Strength of hardened concreteISO 10406-1 Fibre-reinforced polymer (FRP) reinforcement of concrete ndash Test methods ndash Part 1 FRP bars and gridISO 19900 Petroleum and natural gas industries ndash General requirements for offshore structuresISO 19901-1 Petroleum and natural gas industries ndash Specific requirements for offshore structures ndash

Part 1 Metocean design and operating considerationsISO 19901-2 Petroleum and natural gas industries ndash Specific requirements for offshore structures ndash

Part 2 Seismic design procedures and criteriaISO 19901-4 Petroleum and natural gas industries ndash Specific requirements for offshore structures ndash

Part 4 Geotechnical and foundation design considerationsISO 19903 Petroleum and natural gas industries ndash Fixed concrete offshore structuresNORSOK N-003 Actions and Action EffectsNORSOK N-004 Design of Steel StructuresSINTEF STF22 A98741

Eurocrete Modifications to NS3473 when using fibre reinforced plastic (FRP) reinforcement

Table B4 Other references (Continued)Reference Title

212 Characteristic value The representative value associated with a prescribed probability of not beingunfavourably exceeded during some reference period213 Classification Note The Classification Notes cover proven technology and solutions which are found torepresent good practice by DNV and which represent one alternative for satisfying the requirements stipulatedin the DNV Rules or other codes and standards cited by DNV The classification notes will in the same mannerbe applicable for fulfilling the requirements in the DNV offshore standards214 Coating Metallic inorganic or organic material applied to steel surfaces for prevention of corrosion215 Concrete grade A parameter used to define the concrete strength Concrete grades for differentcharacteristic values of concrete strength are provided in Sec4 Table C1 and Table C2216 Corrosion allowance Extra wall thickness added during design to compensate for any anticipatedreduction in thickness during the operation217 Cryogenic temperature The temperature of the stored LNG218 Deck mating Operations through which the deck floated on barges is mated with the concrete supportstructure219 Deformation loads (D) Loads effects on the structure caused by thermal effects prestressing effectscreepshrinkage effects differential settlementsdeformations etc220 Design brief An agreed document where ownersrsquo requirements in excess of this standard should begiven221 Design hazards Hazards likely to occur are identified as part of the risk assessment Design hazards aremitigated into the structural design of the structure222 Design Life The duration to which the parameters used in structural design are related to 223 Design temperature The design temperature for a unit is the reference temperature for areas where theunit will be transported installed and operated The design temperature shall be lower or equal to the lowestdaily mean temperature in air for the relevant areas For seasonal restricted operations the lowest daily meantemperature in air for the season may be applied The cargo temperature shall be taken into account in thedetermination of the design temperature224 Design value The value to be used in the deterministic design procedure ie characteristic valuemodified by the resistance factor or load factor225 Driving voltage The driving voltage is the difference between closed circuit anode potential and theprotection potential226 Ductility The property of a steel or concrete member to sustain large deformations without failure227 Environmental loads (E) Loads from wind wave tide current snow ice and earthquake228 Expected loads and response history Expected loads and response history for a specified time periodtaking into account the number of load cycles and the resulting load levels and response for each cycle229 Expected value The most probable value of a load during a specified time period230 Extreme Level Earthquake (ELE) Earthquake with a severity which the structure should sustain withoutmajor damage When exposed to an ELE a structure is supposed to retain its full capacity for all subsequentconditions231 Fatigue Degradation of the material caused by cyclic loading232 Fatigue critical Structure with calculated fatigue life near the design fatigue life233 Fatigue Limit States (FLS) Limit state related to the possibility of failure due to the effect of cyclic loading234 Fibre mass fraction Ratio of fibre mass to total mass of FRP material235 Fibre made from steel or FRP Short fibres used in structural concrete or grout236 FRP material Fibre reinforced polymer (FRP) composite made from carbon glass aramid or basalt237 Fibre reinforced concrete Structural concrete mixed with short fibre material238 Fibre reinforced grout Structural grout mixed with short fibre material239 Fibre volume fraction Ratio of fire volume to total volume of FRP material240 Functional Loads Permanent (G) and variable loads (Q) except environmental loads (E) to which thestructure can be exposed241 Grout Cementitious material that includes constituent materials cement water and often additions andadmixtures Appropriate fine aggregates may also be included (See also Fibre reinforced grout Neat cementgrout Pre-packed blended grout and Structural grout)242 Hazards identification List of critical elements that will have the potential to cause or contributesubstantially to a major accident if they happen to fail The list is based on consequence of failure only not onlikelihood of failure of the individual hazards

243 High strength concrete A concrete of Grade in excess of C55

244 Hindcasting A method using registered meteorological data to reproduce environmental parameterswhich is mostly used for reproducing wave parameters

245 Inspection Activities such as measuring examination testing gauging one or more characteristics of anobject or service and comparing the results with specified requirements to determine conformity

246 Live loads of permanent character Live loads that the structure may be exposed to for its entire servicelife or a considerable part of it eg weight of furniture stored goods etc

247 Live loads of variable character Live loads that the structure can be exposed to only for limiteddurations much less than the service life such as eg weight of occupants and (not permanently stored)vehicles

248 Light Weight Aggregate Concrete (LWA) A concrete made with lightweight aggregates conforming torequirements contained in recognized standards eg relevant ASTM ACI or EN standard

249 Limit State A state beyond which the structure no longer satisfies the performance requirements Thefollowing categories of limit states are of relevance for structures

ULS = ultimate limit states

FLS = fatigue limit states

ALS = accidental limit states

SLS = serviceability limit states

250 Limit State Design Design of the Offshore Concrete Structure in the limit states of ULS SLS FLS andALS

251 Load and Resistance Factor Design (LRFD) Method for design where uncertainties in loads arerepresented with a load factor and uncertainties in resistance are represented with a material factor

252 Load effect Effect of a single design load or combination of loads on the equipment or system such asstress strain deformation displacement motion etc

253 Lowest daily mean temperature The lowest value on the annual mean daily average temperature curvefor the area in question For temporary phases or restricted operations the lowest daily mean temperature maybe defined for specific seasons

mdash Mean daily average temperature the statistical mean average temperature for a specific calendar daymdash Mean statistical mean based on number of years of observationsmdash Average average during one day and night

254 Lowest waterline Typical light ballast waterline for ships transit waterline or inspection waterline forother types of units

255 Manufacturing Survey Arrangement (MSA) an agreement between DNV and a manufacturer describingthe scope requirements acceptance criteria documentation and the roles and responsibilities of themanufacturer and DNV in connection with the production assessment

256 Material Certificate A certificate to document compliance with the requirements of the applicablestandard It lists characteristic material properties gained through testing Test samples shall be taken from thedelivered products themselves Testing or a part there-of shall be performed in the presence of a third party orin accordance with special agreements

257 Mill certificate A document made by the Manufacturer of cement which contains the results of all therequired tests and which certifies that the tests have been carried out by the Manufacturer on samples takenfrom the delivered cement itself

258 Neat cement grout Grout made from a mixture of cement and water

259 Non-cementitious materials In the context of this Standard non-cementitious materials are materialssuch as epoxy and polyurethane which are specially made for use together with structural concrete to improvethe concrete properties or to supplement repair or replace the concrete

260 Non-destructive testing (NDT) Testing techniques used to evaluate the properties of materialscomponents or systems without causing damage Examples of NDT are inspection of welds with radiographyultrasonic or magnetic powder methods

261 Normal strength concrete A concrete of Grade C25 to C55 The concrete grade is derived from thecharacteristic cylinder strength of concrete in accordance with Sec4 Table C1

262 NV Certificate A Material or Product Certificate issued by DNV when DNV is the certifying third party

263 Offshore Concrete Structure A generic term for floating or fixed structures with are designed withreinforced concrete used in the primary structural members

264 Offshore Standard The DNV offshore standards are documents which presents the principles andtechnical requirements for design of offshore structures The standards are offered as DNVrsquos interpretation ofengineering practice for general use by the offshore industry for achieving safe structures265 Offshore installation A general term for mobile and fixed structures including facilities which areintended for exploration drilling production processing or storage of hydrocarbons or other related activitiesor fluids The term includes installations intended for accommodation of personnel engaged in these activitiesOffshore installation covers subsea installations and pipelines The term does not cover traditional shuttletankers supply boats and other support vessels which are not directly engaged in the activities described above266 One-compartment damage stability The characteristic of a floating object which remains stable even ifone of its compartments is flooded267 Operating conditions Conditions wherein a unit is on location for purposes of production drilling orother similar operations and combined environmental and operational loadings are within the appropriatedesign limits established for such operations (including normal survival and accidental)268 Partial load factor The specified characteristic permanent variable deformation environmental oraccidental loads are modified with a load factor This load factor is part of the safety approach and varies inmagnitude for the different load categories dependent on the individual uncertainties in the characteristic loads269 Permanent Functional Loads (G) Self-weight ballast weight weight of permanent installed parts ofmechanical outfitting external hydrostatic pressure prestressing force etc270 Potential The voltage between a submerged metal surface and a reference electrode271 Pre-packed blended grout Grout proportioned at a factory following strict QAQC procedures and soldin packages for mixing with a predefined amount of water at the construction site272 Prestressing systems Tendons (wires strands and bars) anchorage devices couplers and ducts orsheaths are part of a prestressing system273 Product Certificate A certificate to document compliance with the requirements of the applicablestandard It lists characteristic material properties gained through testing Test samples shall be taken from thedelivered products themselves Testing or a part there-of shall be performed in the presence of a third party orin accordance with special agreements274 Product Data Sheet Sheet issued by the manufacturer with data about the product The datasheet cancontain design data for the product and may be appended to Material Certificates275 Quality Plan A plan implemented to ensure quality in the design construction and in-service inspectionmaintenance An interface manual shall be developed defining all interfaces between the various parties anddisciplines involved to ensure that the responsibilities reporting routines and information routines areestablished276 Recommended Practice (RP) The recommended practice publications cover proven technology andsolutions which have been found by DNV to represent good practice and which represent one alternative forsatisfy the requirements stipulated in the DNV offshore standards or other codes and standards cited by DNV277 Reinforcement Constituents of structural concrete providing the tensile strength that will give thereinforced concrete its ductile characteristics In this standard reinforcement is categorised as

mdash ordinary reinforcementmdash prestressing reinforcementmdash fibre reinforced polymer reinforcement (limited to carbon glass aramid and basalt)mdash special reinforcement

278 Robustness A robust structure is a structure with low sensitivity to local changes in geometry and loads279 Redundancy The ability of a component or system to maintain or restore its function when a failure ofa member or connection has occurred Redundancy may be achieved for instance by introducing alternativeload paths or force redistribution280 Reference electrode Electrode with stable open-circuit potential used as reference for potentialmeasurements281 Reliability The ability of a component or a system to perform its required function without failure duringa specified time interval282 Repair materials Materials used to structurally repair the Offshore Concrete Structure283 Risk The qualitative or quantitative likelihood of an accidental or unplanned event occurring consideredin conjunction with the potential consequences of such a failure In quantitative terms risk is the quantifiedprobability of a defined failure mode times its quantified consequence284 Risk Based Inspection A decision making technique for inspection planning based on risk minus comprisingthe probability of failure and consequence of failure285 Service temperature Service temperature is a reference temperature on various structural parts of theunit used as a criterion for the selection of steel grades or acceptable crack width etc in SLS

286 Service Life Expected lifetime or the expected period of use in service of the facility or structure287 Serviceability Limit States (SLS) Limit state corresponding to the criteria applicable to normal use ordurability288 Sheaths Ducts for post-tensioning tendons Sheaths shall in general be of a semi rigid or rigid type watertight and with adequate stiffness to prevent damages and deformations 289 Short term tensile strength The strength of a FRP bar characterized in a standard test in terms of therupture strength due to tension that increases at a constant rate till rupture The duration of such standard testsis typically 1 ndash 5 minutes290 Slamming Impact load on a member from a rising water surface as a wave passes Slamming can alsooccur within tanks due to stored liquids291 Sloshing Effects caused by the movement of liquid inside a container which is typically also undergoingmotion292 Specified Minimum Yield Strength (SMYS) Specified Minimum Yield Strength is the minimum yieldstrength prescribed by the specification or standard under which the material is purchased293 Specified value Minimum or maximum value during the period considered This value may take intoaccount operational requirements limitations and measures taken such that the required safety level isobtained294 Splash zone The external surfaces of the unit that are periodically exposed to water The determinationof the splash zone includes evaluation of all relevant effects including influence of waves tidal variationssettlements subsidence and vertical motions295 Stability The ability of the floating structure to remain upright and floating when exposed to smallchanges in applied loads Also the ability of a structural member to carry small additional loads withoutbuckling296 Structural concrete Cementitious composite material which is the main ingredient for construction ofconcrete structures297 Structural grout Grout that is part of the load carrying system of the structure Structural grout in thisstandard shall have a characteristic compressive strength higher than 35 MPa The structural grout may be pre-packed blended or neat cement grout298 Submerged zone The part of the unit which is below the splash zone including buried parts299 Survival condition A condition during which a unit may be subjected to the most severe environmentalloadings for which the unit is designed Drilling or similar operations may have been discontinued due to theseverity of the environmental loadings The unit may be either afloat or supported on the sea bed as applicableThe unit stability and possible leakage require assessment

C 300 Terms (continued)301 Target safety level A nominal acceptable probability of structural failure302 Temporary phase conditions Design conditions not covered by operating conditions eg conditionsduring fabrication mating and installation phases transit and towing phases accidental conditions303 Test report A document made by the Manufacturer which contains the results of control tests on currentproduction carried out on products having the same method of manufacture as the consignment but notnecessarily from the delivered products themselves304 Tensile strength Minimum stress level where strain hardening is at maximum or at rupture for steel Forconcrete it is the direct tensile strength of concrete305 Tex Tow size in grams per km length of tow or fibre306 Time to rupture (both fatigue and stress rupture) The time it takes from when a specified load is applieduntil this load causes rupture of the FRP bar Normally the time to rupture under a constant sustained load ismeasured307 Tow Untwisted bundle of fibres in the form they are delivered on bobbins by the fibre supplier(synonym roving untwisted yarn)308 Transit conditions All unit movements from one geographical location to another309 Ultimate Limit States (ULS) Limit state corresponding to the maximum load carrying resistance310 Unit General term for an offshore structure311 Utilisation factor The fraction of anode material that can be utilised for design purposes312 Utilization ratio (UR) For design of concrete structures the utilisation ratio indicating how much acertain resistance is utilized related to the material capacity313 Variable Functional Loads (Q) Weight and loads caused by the normal operation of the OffshoreStructure Variable Functional Loads may vary in position magnitude and direction during the operational

period and includes modules gas weight stored goods pressure of stored components pressures from storedLNG temperature of LNG loads occurring during installation operational boat impacts mooring loads etc

314 Verification Examination to confirm that an activity a product or a service is in accordance withspecified requirements

315 Yarn Twisted bundle of fibres twisted tow

316 Workrsquos Certificate A document signed by the manufacturer stating conformity with DNV rulerequirements that tests are carried on samples taken from the delivered product itself and that tests arewitnessed and signed by a qualified department of the manufacturer

D Abbreviations and Symbols

D 100 Abbreviations

101 Abbreviations as shown in Table D1 are used in this standard

Table D1 AbbreviationsAbbreviation In full

A Accidental loadsACI American Concrete Institute AISC American Institute of Steel ConstructionALE Abnormal Level EarthquakeALS Accidental limit statesAPI American Petroleum InstituteASR Alkali silica reactionASTM American Society for Testing and MaterialsBS British Standard (issued by British Standard Institute)CN Classification noteCoG Centre of gravityD Deformation loadsDDF Deep draught floatersDNV Det Norske VeritasE Environmental loadsELE Extreme Level EarthquakeEN European normETM Event tree methodESD Emergency shut downFLS Fatigue limit stateFM Fracture mechanicsFMEA Failure mode effect analysisFRP Fibre reinforced polymerFTM Fault tree methodG Permanent loadsHAT Highest astronomical tideHAZOP Hazard and operability studyHISC Hydrogen induced stress crackingHS High strength IGC International gas carrierIMO International maritime organisationISO International organisation of standardisationLAT Lowest astronomical tideLNG Liquefied natural gasLRFD Load and resistance factor designLWA Lightweight aggregate concreteMPI Magnetic particle inspectionMSA Manufacturing Survey ArrangementMSF Module support frame

D 200 Symbols201 Latin characters

MSL Mean sea levelNACE National Association of Corrosion EngineersNDT Non-destructive testing NS Norwegian standardNW Normal weight concreteQRA Quantitative risk analysisRP Recommended practiseSLS Serviceability limit stateSMYS Specified minimum yield stressS-N curves Curves specifying fatigue lifeTTR Time to ruptureULS Ultimate limit state

Table D2 Latin CharactersA Distance from the face of the supportA1 Loaded areaA2 Assumed distribution areaAc Concrete area of a longitudinal section of the beam webAc Cross-sectional area of uncracked concreteAcf Effective cross section area of the flange hf beffAF Cross sectional area of FRP reinforcement Af Net fibre area in a FRP reinforcement barAF BAR Cross sectional area of each FRP reinforcement barAF min Minimum area of FRP reinforcement needed to prevent excessive cracking aftow Net fibre area of towAFV Amount of FRP shear reinforcement with spacing s (mm2)AFv min Minimum amount of FRP shear reinforcement with spacing s (mm2)AFs Nominal FRP bar surface areaAs Cross sectional area of steel reinforcement or

Reinforcement area that is sufficiently anchored on both sides of the joint and that is not utilized for other purposes

Ast Area of transverse reinforcement not utilized for other tensile forces and having spacing not greater than 12 times the diameter of the anchored reinforcement If the reinforcement is partly utilized the area shall be proportionally reduced

Asv Amount of shear reinforcementAsx Amount of reinforcement in x-directionAsy Amount of reinforcement in y-directionav Vertical accelerationbeff Part of the slab width which according to Sec6 A400 is assumed as effective when resisting tensile forcesbw Width of beam (web) (mm)bx Length of the side of the critical section (Sec6 F510)by Length of the side perpendicular to bxC Coefficient of characteristic safe service life formula for FRP bar specificationC Concrete grade (normal weight concrete)c1 Minimum concrete cover see Sec6 Table Q2C2 Factor on Woumlhler curves concrete (Sec6 M200)c2 Actual nominal concrete coverC3 Factor on Woumlhler curve reinforcement (Sec6 M200)C4 Factor on Woumlhler curve reinforcement (Sec6 M200)C5 Fatigue strength parameter (Sec6 M200)Cl Factor on Woumlhler curves concrete (Sec6 M200)

Table D1 Abbreviations (Continued)Abbreviation In full

D Deformation loadD Distance from the centroid of the tensile reinforcement to outer edge of the compression zoned1 1000 mmDF Nominal diameter of FRP barDk Diameter of the concrete core inside the centroid of the spiral reinforcement AssE Environmental loade Eccentricity of loadingEcd Design value of Youngrsquos Modulus of concrete used in the stress-strain curveEcn Normalized value of Youngrsquos Modulus of concrete used in the stress-strain curveEF Characteristic value of the Youngrsquos modulus of FRP reinforcement bar (referred to nominal bar area AF)EFd Design value of Youngrsquos Modulus of FRP barsEsd Design value of Youngrsquos Modulus of steel reinforcementEsk Characteristic value of Youngrsquos Modulus of steel reinforcement (200 000 MPa)fbc Concrete related portion of the design bond strength in accordance with Sec6 K116fbd Design bond strength calculated in accordance with Sec6 K116fc2d Truss analogy design compressive strength (Sec6 F308) in the compression field

General reduced design compressive strength (Sec6 H107) fcck Characteristic concrete compressive cylinder strengthfcck2 94 MPa (Sec4 C307)fcckj Characteristic strength of the taken specimens converted into cylinder strength for cylinders with height

diameter ratio 21fcckt Characteristic compressive cylinder strength at 28 days based on in-situ testsFcd Compressive capacityfcd Design compressive strength of concretefck Characteristic concrete cube strengthfcn Normalized compressive strength of concreteFd Design loadFF Tensile force at rupture of FRP barfF Characteristic short term tensile strength (force per area) of FRP barfF bend Characteristic tensile strength of bent portion of FRP bar fFb Design strength of the bend portion of FRP barfFd Design strength of FRP reinforcementfF TTR(i) Characteristic tensile strength (force per area) in FRP bar until failure at considered load duration i derived

from characteristic TTR curve i is taken as I II II corresponding to load durations of 50 years 1 year and 1 week respectively

Fk Characteristic loadfrd Reference strength for use in fatigue calculation dependant on the type of failure in question (Sec6 M200)frd fat Reference strength for use in fatigue calculation dependant on the type of failure in question (Sec6 M200)

including the material specific factor C5fsd Design strength of steel reinforcementfsk Characteristic strength of steel reinforcementfssd Design strength of the spiral reinforcement AssFSV Additional tensile force in longitudinal reinforcement due to shearftd Design strength of concrete in uni-axial tensionftk Characteristic tensile strength of concreteftk ftk + 05 pw for structures exposed to pressure from liquid or gas in the formulae for calculating the required

amount of minimum reinforcement (Sec6 Q603)ftn Normalized tensile strength of concreteFvn Force corresponding to shear failure at cross wire welds within the development lengthG Permanent loadg go Acceleration due to gravityH Cross-section heighthrsquo Distance between the centroid of the reinforcement on the ldquotensilerdquo- and ldquocompressionrdquo side of the memberhf Thickness of the flange (the slab)Ic Moment of inertia of AcL Length of FRP bar

Table D2 Latin Characters (Continued)

lrsquob Development length for welded wire fabriclb Development length bond ndash bars or bundle of barslbp Development length for the prestressing forcele Effective length theoretical buckling lengthLi Distance between zero moment pointslsk Influence length of the crack considering that some slippage in the bond between reinforcement and concrete

may occur (Sec6 O802)M MomentM εco εcnMf Total moment in the section acting in combination with the shear force Vfmf Mass fraction of fibres (average from production records)mm Average mass fraction of matrix resin (mm = 1 ndash mf)| MOA | Numerical smallest member end moment calculated from 1 order theory at end A| MOB | Numerical largest member end moment calculated from 1 order theory at end Bmtex Tow or fibre mass expressed in tex (gkm)N Exponent of Findleyrsquos creep rate equationN Design life of concrete subjected to cyclic stressesnf Nf fcdAcNf Design axial force (positive as tension)ni Number of cycles in stress-block i (Sec6 M108)Ni Number of cycles with constant amplitude which causes fatigue failure (Sec6 M108)Nx Axial force in x-directionNxy Shear force in the x-y planeNy Axial force in y-directionP LoadP Pressurepd Design pressureQ Variable functional loadR Radiusrc Radius of curvatureRd Design resistanceRk Characteristic resistances Centre to centre distance between the spiral reinforcement measured in the longitudinal direction of the

column (Sec6 D106) or spacing between shear reinforcement in longitudinal directions1 Spacing of the transverse reinforcementSc Area moment about the centroid axis of the cross-section for one part of the concrete sectionSd Design load effectSk Characteristic load effectT Specified longitudinal tolerance for the position of the bar endtapp max Maximum temperature of application defined by the manufacturer for a grout or fibre reinforced grout Shall

be taken as +30degC in the absence of data from an elevated temperature test programmetapp min Minimum temperature of application defined by the manufacturer for a grout or fibre reinforced grout Shall

be taken as +5degC in the absence of data from a low temperature test programme ttest max Temperature which the equipment constituent materials and test and curing environments shall be

maintained at during material testing of grout to be qualified for application at temperatures above 30degCttest min Temperature which the equipment constituent materials and test and curing environments shall be

maintained at during material testing of grout to be qualified for application at temperatures below +5degC (Sec9 E209)

Vccd Design shear capacity of a concrete cross-section(shear compression mode of failure)

Vcd Design shear capacity of a concrete cross-section(shear tension made of failure)

Vf Design shear force for the cross section under considerationVmax Maximum shear force within fatigue stress block

Vmin Minimum shear force within fatigue stress block

Vsd Design shear capacity of transverse reinforcement (shear tension mode of failure)

202 Greek characters

Wc Section modulus of the concrete cross section with respect to the extreme tension fibre or the fibre with least compression

wk Nominal characteristic crack widthsZ 09 d for sections with a compression zonez1 The greater of 07 d and Ic Sc

Table D3 Greek Charactersα Angle between transverse shear reinforcement and the longitudinal axis

alsoAngle between the reinforcement and the contact surface where only reinforcement with an angle between 90deg and 45deg (to the direction of the force) shall be taken into account

αF Thermal expansion coefficient of FRP reinforcement

β Opening angle of the bend (Sec6 L112)δ DeflectionΔσ Stress variation of the reinforcement (MPa) (Sec6 M202)ε Strainε1 average principal tensile strain (Sec6 H107)εcu Max strain NW concrete (25 m ndash 15)εcn (Sec6 C114)εcm Mean stress dependent tensile strain in the concrete at the same layer and over the same length as εsm

(Sec6 O802)εcs Free shrinkage strain of the concrete (negative value) (Sec6 O802)εs1 Tensile strain in reinforcement slightly sensitive to corrosion on the side with highest strain (Sec6 O307)εs2 Tensile strain at the level of the reinforcement sensitive to corrosion (Sec6 O307)εsm Mean principal tensile strain in the reinforcement in the crackrsquos influence length at the outer layer of the

reinforcement (Sec6 O802)γc Material factor for concreteγf Partial load factorγm Material factor (material coefficient)γs Material factor for steel reinforcementγF Material factor to account for statistical variation in the material strength potential placement inaccuracy in

the section due to the physical characteristics of the bars and the level of control implemented during manufacturing of FRP bars

γFI Material factor to be used for ULS check with load combination type I for FRP barsγFII Material factor to be used for ULS check with load combination type II for FRP barsγFIII Material factor to be used for ULS check with load combination type III for FRP barsγFssa Material factor to be used for long term safe service life assessment for FRP barsγFA Material factor to be used in accidental limit states for FRP barsγFE Material factor applied to Youngrsquos modulus to account for long term creep of the FRP bars It is used to

determine strains and deformations for ULS SLS FLS and ALSγFS Material factor to be used in serviceability limit states for FRP barsλ Geometric slenderness ratio λN Force dependent slenderness θ Angle between the inclined concrete compression struts and the longitudinal axis in the truss model methodφ Diameter of the reinforcement barφe Equivalent diameter in term of reinforcement cross sectionμ Friction coefficientρ Coefficient of Findleyrsquos creep rate equationρ Densityρ1 2200 kgm3

ρF Density of FRP bars (kgm3)ρf Fibre densityρm Matrix densityρx Reinforcement ratio in x ndash direction = Asx (b middot d)ρy Reinforcement ratio in y ndash direction = Asy (b middot d)η Limit for cumulative damage ratio

203 Subscripts

ηb Conversion factor for bends for the bend radiuses coveredηF TTR Conversion factor derived from the characteristic time to rupture curve for the load durations under

considerationηT Conversion factor for tensile strength of FRP reinforcement from room temperature to specified service

temperatureηtemp Temperature constant to allow for inaccuracies in maintaining and recording low temperatures during grout

concrete testing as well as inaccuracies associated with temperature forecasting offshore (Appendix H) ϕ Creep coefficientσF Stress in a FRP bar in response to specified loading (referred to nominal bar area)σf Stress in the fibres in a FRP bar in response to specified loading (referred to net fibre area)σc Concrete stress due to long-term loadingσd Design stressσM Edge stress due to bending alone (tension positive) (Sec6 O801)σmax Numerically largest compressive stress calculated as the average value within each stress-blockσmin Numerically least compressive stress calculated as the average value within each stress-blockσN Stress due to axial force (tension positive) (Sec6 O801)σp Steel stress due to prestressingσtrough Stress at the trough of the stress cycle (minimum stress)σpeak Peak stress of the stress cycle (maximum stress)τcd Bond strength τbmax Maximum bond stress within fatigue stress blockτbmin Minimum bond stress within fatigue stress blockvf Volume fraction of fibre in FRP bar

Table D4 SubscriptsD Design value K Characteristic value P PlasticY Yield

Table D3 Greek Characters (Continued)

SECTION 2SAFETY PHILOSOPHY

A General

A 100 Objective101 The purpose of this section is to present the safety philosophy and corresponding design format appliedin this standard102 This section applies to Offshore Concrete Structures which shall be built in accordance with thisstandard 103 This section also provides guidance for extension of this standard in terms of new criteria etc104 The integrity of an Offshore Concrete Structure designed and constructed in accordance with thisstandard is ensured through a safety philosophy integrating different parts as illustrated in Figure 1105 An overall safety objective shall be established planned and implemented covering all phases fromconceptual development until abandonment

Figure 1 Safety Philosophy structure

A 200 Systematic review201 As far as practical all work associated with the design construction and operation of the OffshoreConcrete Structure shall be such as to ensure that no single failure will lead to life-threatening situations forany person or to unacceptable damage to the Structure or the environment202 A systematic review or analysis shall be carried out for all phases in order to identify and evaluate theconsequences of single failures and series of failures in the Offshore Concrete Structure such that necessaryremedial measures can be taken The extent of the review or analysis shall reflect the criticality of the OffshoreConcrete Structure the criticality of a planned operation and previous experience with similar systems oroperations

Guidance noteA methodology for such a systematic review is quantitative risk analysis (QRA) This may provide an estimation ofthe overall risk to human health and safety environment and assets and comprises

- hazard identification- assess probabilities of failure events- accident developments and - consequence and risk assessmentIt should be noted that legislation in some countries requires risk analysis to be performed at least at an overall levelto identify critical scenarios that might jeopardise the safety and reliability of the Structure Other methodologies foridentification of potential hazards are Failure Mode and Effect Analysis (FMEA) and Hazard and Operability studies(HAZOP)

---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---

A 300 Safety class methodology301 Offshore Concrete Structures are classified as safety class 3 based on failure consequences Fordefinition see Table A1

SafetyObjective

SystematicReview (QRA)

Safety ClassMethodology

Qualityassurance

A 400 Quality assurance401 The safety format within this standard requires that gross errors (human errors) shall be controlled byrequirements for organisation of the work competence of persons performing the work verification of thedesign and quality assurance during all relevant phases402 For the purpose of this standard it is assumed that the owner of the Offshore Concrete Structure hasestablished a quality objective The owner shall in both internal and external quality related aspects seek toachieve the quality level of products and services intended in the quality objective Further the owner shallprovide assurance that intended quality is being or will be achieved403 The quality system shall comply with the requirements of ISO 9000 and specific requirements quotedfor the various engineering disciplines in this Standard404 All work performed in accordance with this standard shall be subject to quality control in accordancewith an implemented Quality Plan The Quality Plan should be in accordance with the ISO 9000 series Theremay be one Quality Plan covering all activities or one overall plan with separate plans for the various phasesand activities to be performed405 The Quality Plan shall ensure that all responsibilities are defined An Interface Manual should bedeveloped that defines all interfaces between the various parties and disciplines involved and ensure thatresponsibilities reporting and information routines as appropriate are established

A 500 Health safety and environment501 The objective of this standard is that the design materials fabrication installation commissioningoperation repair re-qualification and abandonment of the Offshore Concrete Structure are safe and conductedwith due regard to public safety and the protection of the environment

A 600 Qualifications of personnel601 All activities that are performed in the design construction transportation inspection and maintenanceof offshore structures according to this Standard shall be performed by skilled personnel with the qualificationsand experience necessary to meet the objectives of this Standard Qualifications and relevant experience shallbe documented for all key personnel and personnel performing tasks that normally require special training orcertificates602 National provisions on qualifications of personnel such as engineers operators welders divers etc inthe place of use apply Additional requirements may be given in the project specification

B Design Format

B 100 General101 The design format within this standard is based upon a limit state and partial safety factor methodologyalso called Load and Resistance Factor Design format (LRFD) The design principles are specified in Sec2 ofDNV-OS-C101 The design principle is based on LRFD but design may additionally be carried out by bothtesting and probability based design The aims of the design of the Offshore Concrete Structure and its elementsare to

mdash Withstand loads likely to occur during all temporary operating and damaged conditionsmdash Maintain acceptable safety for personnelmdash Have adequate durability against deterioration during the design life of the Offshore Concrete Structuremdash Provide sufficient safety against pollution

102 The design of a structural system its components and details shall as far as possible account for thefollowing principles

mdash Resistance against relevant mechanical physical and chemical deterioration is achievedmdash Fabrication and construction comply with relevant recognised techniques and practicemdash Inspection maintenance and repair are possible

103 Structures and elements thereof shall possess ductile resistance Ductile behaviour of concrete structuresis required in order to ensure that the structure to some extent can withstand abnormal or accidental loads and

Table A1 Safety ClassesConsequences of failure Safety Class

Minor 1Serious 2Very serious 3

that a redistribution of the loads can take place The requirements provided in this standard do not ensuresufficient ductility that may be required for ALE loading In this case ductility shall be documented

104 Requirements to materials are given in Section 4 Loads and Analyses Requirements in Section 5Detailed Design of Offshore Concrete Structures in Section 6 Construction in Section 7 and In-serviceInspection Maintenance and Conditioned Monitoring in Section 8

105 Additionally in Appendices A to F guidelines are given for

mdash environmental loading (A)mdash structural analyses ndash modelling (B)mdash structural analyses (C)mdash use of alternative design standard (D)mdash crack width calculation (E)mdash QAQC system for manufacture of FRP bars (F)

106 The design life of the Offshore Concrete Structure shall be decided by the Owner of the facility Aminimum of 50 years design life shall be used

107 In the case of structures reinforced with FRP reinforcement a minimum of 50 years design life shall beused

108 The design life to be used for FRP reinforced structures shall ensure that regardless of foreseeable lifeextensions the FRP bars shall not be the limiting factor to the extension of service lifetime of the structure Itis not acceptable to base future life extensions on inspection and maintenance of the FRP bars unless it is basedon a documented method to determine the remaining lifetime of the bars

C Identification of Major Accidental Hazards

C 100 General

101 The standard has identified common accidental hazards for an Offshore Concrete Structure The designershall ensure itself of its completeness by documenting through a hazard identification and risk assessmentprocess that all hazards which may be critical to the safe operation of the Offshore Concrete Structure havebeen adequately accounted for in design This process shall be documented

102 Criteria for the identification of major accident hazards shall be

mdash loss of lifemdash significant damage to the asset mdash significant damage to the environment

There should be a clear and documented link between major accident hazards and the critical elements

103 The following inputs are normally required in order to develop the list of critical elements

mdash description of Structure and mode(s) of operation including details of the asset manningmdash equipment list and layoutmdash hazard identification report and associated studiesmdash safety case where applicable

104 The basic criteria in establishing the list of critical elements is to determine whether the systemcomponent or equipment which ndash should they fail ndash have the potential to cause or contribute substantially toa major accident This assessment is normally based upon consequence of failure only not on the likelihood offailure

105 The following methodology should be applied for confirming that prevention detection control ormitigation measures have been correctly identified as critical elements

mdash Identify the major contributors to overall riskmdash Identify the means to reduce riskmdash Link the measures the contributors to risk and the means to reduce risk to the assetsrsquo systems ndash these can

be seen to equate to the critical elements of the asset

106 The record of critical elements typically provides only a list of systems and types of equipment structureetc In order to complete a meaningful list the scope of each element should be clearly specified such that therecan be no reasonable doubt as to the precise content of each element

107 The above processes should consider all phases of the lifecycle of the structure

108 The hazard assessment shall consider as a minimum the following events

mdash damage to the primary structure due tomdash extreme weathermdash ship collisionmdash dropped objectsmdash helicopter collisionmdash exposure to unsuitable coldwarm temperaturemdash exposure to high radiation heatmdash fire and explosionmdash loss of Primary Liquid Containment (duration shall be determined based on an approved contingency plan)mdash oilgas leakagemdash release of flammable or toxic gas to the atmosphere or inside an enclosed spacemdash loss of stabilitymdash loss of any single component in the station keepingmooring systemmdash loss of ability to offload oilgasmdash loss of any critical component in the process systemmdash loss of electrical power

109 The results of the Hazard Identification and Risk Assessment shall become an integrate part of thestructural design of the Offshore Concrete Structure

D Life extensions

D 100 General101 Life extension assessment shall be based on a combination of Risk Based Inspection re-evaluation ofapplied loads and load combinations and prediction of remaining life based on material deterioration chlorideingress carbonation and remaining fatigue life102 Risk Based Inspection shall be performed considering

mdash Results of earlier inspections related to visual damage to the concrete surface and possible repairs mdash Changes that may have been engineered related to load situations both from external pay load internal load

from wateroil pressures in tanks mdash Changes in the combinations of original load situations

103 In cases where either the geometry of the structure has changed or the material has degenerated makingthe original global analyses invalid with respect to the prediction of internal force distribution a new finiteelement model shall be prepared 104 Compliance with applicable standards shall be checked In cases where the structure does not meet thedesign requirements due to new loads load cases or changes in geometry non-linear analyses may be carriedout to establish the consequence of redistributing forces to remaining structural elements105 Based on earlier and future load history the remaining fatigue life of the structure shall be predictedaccording to applicable standards

SECTION 3DESIGN DOCUMENTATION

A General

A 100 Introduction

101 Documentation shall be prepared for all activities including design construction transportation andinstallation Documentation shall also be prepared showing records of all inspection and control of materialsused and execution work performed that has an impact on the quality of the final product The documentationshall be suitable for independent verification

102 Necessary procedures and manuals shall be prepared to ensure that the construction transportationinstallation and in-service inspection are performed in a controlled manner in full compliance with allassumptions of the design

103 The most important assumptions on which the design construction and installation work is based withregard to the Offshore Concrete Structure shall be presented in a Summary Report The Summary Report shallbe available and suitable for use in connection with operation maintenance alterations and possible repairwork The summary report will normally be based on the documentation identified in A400 and A500

A 200 Overall Planning

201 A fixedfloating Offshore Concrete Structure shall be planned in such a manner that it can meet allrequirements related to its functions and use as well as its structural safety and durability requirementsAdequate planning shall be done before actual design is started in order to have sufficient basis for theengineering and by that obtain a safe workable and economical structure that will fulfil the required functions

202 The initial planning shall include determination and description of all the functions the structure shallfulfil and all the criteria upon which the design of the structure are based Site-specific data such as water depthenvironmental conditions and soil properties shall be sufficiently known and documented to serve as basis forthe design All functional and operational requirements in temporary and service phases as well as robustnessagainst accidental conditions that can influence the layout and the structural design shall be considered

203 All functional requirements to the structure affecting the layout and the structural design shall beestablished in a clear format such that it can form the basis for the engineering process and the structural design

204 Investigation of site-specific data such as seabed topography soil conditions and environmentalconditions shall be carried out in accordance with requirements of DNV-OS-C101 ISO 19901-1 ISO 19901-2 and ISO 19901-4

A 300 Documentation required in the planning stage

Description of Offshore Concrete Structure

301 The objective is to provide an overview of the offshore structure highlighting key assumptions andoperational phases of the development

302 The overview should be presented in three sections

mdash Overview of facilitymdash Development bases and phasesmdash Staffing philosophy and arrangements

Cross-references to data sources figures etc should be provided

Meteorological and ocean conditions

303 The objective is to summarise key design parameters with cross-references to key technical documents

304 The metoceanclimatology conditions section should cover at least the following

mdash stormwavecurrent conditionsmdash windmdash seawaterair temperaturemdash earthquakesmdash cyclonesmdash other extreme conditionsmdash seabed stabilitymdash tsunami mdash atmospheric stabilitymdash range and rates of changes of barometer pressure

mdash rainfall snowmdash corrosive characteristics of the airmdash frequency of lightning strikes mdash relative humidity

305 For ground supported structures located in seismic active zones a site specific earthquake analysis shallbe performed This analysis shall be reported in a Seismic Hazard Assessment Report where geological andseismic characteristics of the location of the ground supported facilities and the surrounding region as well asgeo-tectonic information from the location have to be taken into account As a conclusion this report shallrecommend all seismic parameters required for the design

The potential of earthquake activity in the vicinity of the proposed site is determined by investigating theseismic history of the region surrounding the site and relating it to the geological and tectonic conditions

These investigations involve thorough research review and evaluation of all historically reported earthquakesthat have affected or that could reasonably be expected to have affected the site

Layout of the Offshore Concrete Structure

306 The objective is to provide a description of the Offshore Concrete Structure its unique features (if any)equipment layout for all decks and interaction with existing offshoreonshore facilities

307 This section should include a description of at least the following (where applicable)

mdash General

mdash structureplatformmdash geographical locationmdash water depth

mdash Layout

mdash orientation of the structuremdash elevationplan viewsmdash equipmentmdash escape routesmdash access to sea deckmdash emergency assembly area etcmdash structural details including modelling of structure and loadings

mdash Interaction with existing facilities

mdash physical connectionsmdash support from existing facilities

mdash Interaction with expected facilities (where applicable)

Description of primary functions

mdash A description of primary functions is required as background information essential for identification ofstructural hazards of importance for the design of the structural load bearing structure of the terminal

308 The primary functions section should include a description of at least the following (where applicable)

Process systems

mdash process description (overview)mdash process control featuresmdash safety control systems for use during emergencies eg controls at the TR or emergency assembly area

Oil storage system

mdash oil storage tankmdash pipingmdash layoutmdash electricalmdash monitoring

Pipeline and riser systems

mdash location separation protectionmdash riser connectdisconnect system

Utility systems

mdash power generation and distributionmdash communicationsmdash other utility systems (eg instrument air hydraulics cranes)

Inert gas systems

mdash safety features (eg blow-out prevention systems)mdash integration with platform systems

Workover and wireline systems

mdash extent and type of activity plannedmdash integration with platform systems

Marine functionssystems

mdash supplymdash standby vesselsmdash divingmdash ballast and stability systems mdash mooring systemsmdash oilgas offloading systemmdash oilgas vessel mooring system

Helicopter operations

mdash onshore basemdash capability of aircraftmdash helicopter approach

Standards

309 A design brief document shall include references to Standards and design specifications

A 400 Documentations required prior to construction

401 The technical documentation of a concrete structure available prior to construction shall comprise

mdash design basismdash design calculations for the complete structure including individual membersmdash project specification and proceduresmdash drawings issued for construction and approved by design manager

402 All technical documentation shall be dated signed and verified

403 The Project Specification shall comprise

mdash Construction drawings giving all necessary information such as geometry of the structure amount andposition of reinforcing and prestressing steel and for precast concrete elements tolerances lifting devicesweights inserts etc

mdash Description of all products to be used with any requirements to the application of the materials Thisinformation should be given on the drawings andor in the work description Material specificationsproduct standards etc shall be included Material Certificates and data-sheets defining a coherent set ofmaterial factors and characteristic material properties for design shall be provided if not provided in thisStandard

mdash Work description (procedures) related to the construction activity

404 The work description should also include all requirements to execution of the work ie sequence ofoperation installation instructions for embedment plates temporary supports work procedures etc

405 The work description shall include an erection specification for precast concrete elements comprising

mdash Installation drawings consisting of plans and sections showing the positions and the connections of theelements in the completed work

mdash Installation data with the required material properties for materials applied at sitemdash Installation instructions with necessary data for the handling storing setting adjusting connection and

completion works with required geometrical tolerancesmdash Quality control procedures

A 500 ldquoAS-BUILTrdquo documentation501 The As-Built documentation shall comprise

mdash design basismdash design brief documentationmdash updated design calculationsmdash geotechnical design reportmdash quality recordsmdash method statementsmdash sources of materials material test certificates andor suppliers attestation of conformity Workrsquos certificate

(mill certificate) approval documentsmdash applications for concessions and responsesmdash as-built drawings or sufficient information to allow for preparation of as-built drawings for the entire

structure including any precast elementsmdash a description of non-conformities and the results of possible corrective actionsmdash a description of accepted changes to the project specificationmdash records of possible dimensional checks at handovermdash a diary or log where the events of the construction process are reportedmdash documentation of the inspection performed

A 600 Inspectionmonitoring plans for structure in service601 Documentation related to monitoring and inspection of the installation shall be prepared

SECTION 4MATERIALS

A General

A 100 General

101 The requirements to properties composition extent of testing inspection etc for materials for OffshoreConcrete Structures ie concrete grout mortar and reinforcement are given in this Section

102 The materials for all structural components and for the structure itself shall be specified to ensure thatthe required quality is maintained during all stages of construction and for the intended structural life

103 Materials may be rejected during manufacture or after being delivered to the construction sitenotwithstanding any previous acceptance or certification if it is established that the conditions upon which theapproval or certification was based were not fulfilled

104 Specifications shall be established for all relevant materials including constituents to be used in themanufacture of the Offshore Concrete Structure The specifications shall comply with the requirements in thisStandard

105 Material properties shall be documented and it shall be verified through on-going testing that they meetthe requirements as set out in the material specification

106 All testing shall be performed in accordance with recognized standards as stated in the projectspecification or otherwise agreed upon Testing shall be witnessed and signed by a qualified departmentdifferent from the production department and documented in accordance with the requirements of this standardIn addition relevant requirements stated in this section Section 6 and Section 7 shall be complied with

107 Materials complying with other recognized standards may be accepted as an alternative to this Standard

108 Materials with properties other than specified in this Section may be accepted after special consideration

109 For details of Material Certificates for FRP reinforcement and for structural grout with and without fibressee Appendix F and Appendix H

B ConcreteGrout Constituents

B 100 General

101 Approval of concrete constituents is based on material testing where chemical composition mechanicalproperties and other specified requirements are checked against this Standard and other approvedspecification(s)

102 Constituent materials for structural concrete are cement aggregates water and eventually admixtures Itmay also include additions

103 Constituent materials shall be sound durable free from defects and suitable for making concrete that willattain and retain the required properties Constituent materials shall not contain harmful ingredients inquantities that can be detrimental to the durability of the concrete or cause corrosion of the reinforcement andshall be suitable for the intended use

104 Approval of concrete constituents and reinforcements shall be based on material testing where chemicalcomposition mechanical properties and other specified requirements are tested according to and are checkedagainst applicable International Standards and approved specifications In lieu of relevant InternationalStandards for specific test methods and requirements other recognized national standards shall be used In theabsence of such standards also recognized recommendations from international or national bodies may beused

B 200 Cement

201 Only cement with established suitability shall be used Its track record for good performance anddurability in marine environments and after exposure to stored oil if relevant shall be demonstrated Cementshall be tested and delivered in accordance with a standard recognized in the place of use

202 Cement shall be tested according to an approved method Table B1 gives the tests and the preferredmethod of testing required for documentation References to recognized standards are given For undatedreferences the latest edition of the referenced document (including any amendments) applies

203 The compound (mineral) composition of cements may be calculated with sufficient accuracy fromBogues unmodified formulae as given in ASTM C150

Guidance noteThe tricalcium aluminate (C3A) content calculated according to this clause should preferably not exceed 10However as the corrosion protection of embedded steel is adversely affected by a low C3A content it is not advisableto aim for values lower than approx 5 The imposed limits should not be too strictly enforced but should beevaluated in each case

204 Cement shall be delivered with a Worksrsquo Certificate (Mill Certificate) containing at least the followinginformation

mdash Physical properties ie fineness setting times strength in mortar normal consistency and soundness etcmdash Chemical composition including mineralogical composition loss on ignition insoluble residue sulphate

content chloride content and pozzolanity

The certificate should in addition to confirming compliance with the specified requirements also state thetypegrade with reference to the approved standardspecification batch identification and the tonnagerepresented by the document205 The following types of Portland cement are in general assumed to be suitable for use in structuralconcrete in a marine environment if unmixed with other cements

mdash Portland cementsmdash Portland composite cementsmdash Blast furnace cements with high clinker content

Provided suitability is demonstrated also the following types of cement may be considered

mdash Blast furnace cementsmdash Pozzolanic cementsmdash Composite cement

The above types of cement have characteristics specified in international and national standards They can bespecified in grades based on the 28-day strength in mortar Cements shall normally be classified as normalhardening rapid hardening or slowly hardening cements

Guidance noteLow heat cement may be used where heat of hydration may have an adverse effect on the concrete during curing

B 300 Mixing water301 Only mixing water with established suitability shall be used The mixing water shall not containconstituents in quantities that can be detrimental to the setting hardening and durability of the concrete or cancause corrosion of the reinforcement Drinking water from public supply may normally be used without furtherinvestigation302 The required water content shall be determined by considering the strength and durability of hardenedconcrete and the workability of fresh concrete The water to cement ratio by weight may be used as a measureFor requirements to WC ratio see C203303 Water resulting in a concrete strength of less than 90 of that obtained by using distilled water shall notbe used neither shall water that reduces the setting time to less than 45 min or change the setting time by morethan 30 min relative to distilled water be used304 Salt water (eg raw seawater) shall not be used as mixing or curing water for structural concrete305 Water source(s) shall be investigated and approved for their suitability and dependability for supply

Table B1 Testing of Cement

Property MethodApparatusCode References

ASTM EN ISOFineness Blaine C204 196-6Chemical composition Cl14 196-2Normal consistency Vicat C187 196-3 9597Soundness Le Chatelier 196-3 9597Initialfinal set Vicat C191 196-3 9597Strength in mortar Rilem 196-1

306 Icy water may be used as mixing water provided the water melts before or during the mixing processensuring a resulting good mixture of the water cement aggregate and admixture

B 400 Normal weight aggregates

401 Aggregate source(s) (sand and gravel) shall be investigated and reviewed for their suitability anddependability for supply

Only aggregates with established suitability shall be used Aggregates for structural concrete shall havesufficient strength and durability They shall not become soft be excessively friable or subject to expansion

They shall be resistant to decomposition when wet They shall not react with the products of hydration of thecement-forming products and shall not affect the concrete adversely Marine aggregates shall not be usedunless they are properly and thoroughly washed to remove all chlorides

402 Aggregates shall be delivered with a test report containing at least the following listed information

mdash description of the sourcemdash description of the production systemmdash particle size distribution (grading) including silt content mdash particle shape flakiness etcmdash porosity and water absorptionmdash content of organic mattermdash density and specific gravitymdash strength in concrete and mortarmdash potential reactivity with alkalis in cementmdash petro-graphical composition and properties that may affect the durability of the concrete

403 Normal weight aggregates shall in general be of natural mineral substances They shall be eithercrushed or uncrushed with particle sizes grading and shapes such that they are suitable for the production ofconcrete Relevant properties of aggregate shall be defined eg type of material shape surface texturephysical properties and chemical properties Aggregates shall be free from harmful substances in quantities thatcan affect the properties and the durability of the concrete adversely Examples of harmful substances areclaylike and silty particles organic materials and sulphates and other salts

404 Aggregates shall be evaluated for risk of Alkali Silica Reaction (ASR) in concrete according tointernationally recognized test methods Suspect aggregates shall not be used unless specifically tested andapproved The approval of an aggregate that might combine with the hydration products of the cement to causeASR shall state which cement the approval applies to The aggregate for structural concrete shall havesufficient strength and durability

405 An appropriate grading of the fine and coarse aggregates for use in concrete shall be established Thegrading and shape characteristics of the aggregates shall be consistent throughout the concrete production

406 Aggregates of different grading shall be stockpiled and transported separately

407 Aggregates may generally be divided into two groups these being

mdash sand or fine aggregate (materials less than 5 mm)mdash coarse aggregate (materials larger than 5 mm)

408 Maximum aggregate size shall be specified based on considerations concerning concrete propertiesspacing of reinforcement and cover to the reinforcement

409 Testing of aggregates shall be carried out at regular intervals both at the quarry and on construction siteduring concrete production The frequency of testing shall be determined taking the quality and uniformity ofsupply and the concrete production volume into account The frequency of testing shall be in accordance withInternational standards

B 500 Lightweight aggregates

501 Lightweight aggregates in load bearing structures shall be made from expanded clay expanded shaleslate or sintered pulverized ash from coal-fired power plants or from other aggregates with correspondingdocumented properties Only aggregates with established suitability shall be used

502 Lightweight aggregates shall conform to requirements contained in recognized standards eg relevantASTM ACI or EN

503 Lightweight aggregates shall have uniform strength properties stiffness density degree of burninggrading etc The dry density shall not vary more than plusmn75

B 600 Additions

601 Additions shall conform to requirements of International standards and only additions with establishedsuitability shall be used

602 Additions shall not be harmful or contain harmful impurities in quantities that can be detrimental to thedurability of the concrete or the reinforcement Additions shall be compatible with the other ingredients of theconcrete The use of combinations of additions and admixtures shall be carefully considered with respect to theoverall requirements of the concrete The effectiveness of the additions shall be checked by trial mixes603 Latent hydraulic or pozzolanic supplementary materials such as silica fume pulverized fly ash andgranulated blast furnace slag may be used as additions The amount is dependent on requirements toworkability of fresh concrete and required properties of hardened concrete The content of silica fume used asadditions should normally not exceed 10 of the weight of Portland cement clinker When fly ash slag or otherpozzolana is used as additions their content should normally not exceed 35 of the total weight of cement andadditions When Portland cement is used in combination with only ground granulated blast furnace slag theslag content may be increased The clinker content shall however not be less than 30 of the total weight ofcement and slag604 The total amount of chlorides in the fresh concrete calculated as free calcium chloride shall not exceed03 of the weight of cement605 Additions shall be delivered with a Works Certificate containing relevant chemical and physicalproperties

B 700 Admixtures701 Admixtures to be used in concrete shall be tested under site conditions to verify that these products willyield the required effects without impairing the other properties required A test report shall be prepared todocument such verification The test report shall form a part of the concrete mix design documentation702 Relevant test report(s) from a recognized laboratory shall be submitted before use of an admixture703 The extent of testing is normally to be in accordance with the requirements given in recognizedInternational Standards704 Air-entraining admixtures may be used to improve the properties of hardened concrete with respect tofrost resistance or to reduce the tendency of bleeding segregation or cracking705 For investigations carried out under site conditions the following properties shall be tested

mdash consistence eg at 5 and 30 minutes after mixingmdash water requirement for a given consistencemdash shrinkageswellingmdash strength in compression and tension (bending) at 1-3 28 and 91 days

706 Admixtures shall be delivered with a Works Certificate containing relevant chemical and physicalproperties

C Concrete

C 100 Concrete categorization101 Normal Strength Concrete is a concrete of Grade C25 to C55 The Concrete Grade is derived from thecharacteristic cylinder strength of concrete in accordance with Table C1102 High Strength Concrete is a concrete of Grade in excess of C55 103 Lightweight Aggregate Concrete (LWA) is a concrete made with lightweight aggregates 104 LWA may be composed using a mixture of lightweight and normal weight aggregates

C 200 Concrete mix201 The concrete composition and the constituent materials shall be selected to satisfy the requirements ofthis Standard and the project specifications for the fresh and hardened concrete such as consistence densitystrength durability and protection of embedded steel against corrosion Due account shall be taken of themethods of execution to be applied The requirements of the fresh concrete shall ensure that the material is fullyworkable in all stages of its manufacture transport placing and compaction202 The required properties of fresh and hardened concrete shall be verified by the use of recognized testingmethods International Standards or recognized national standards Recognized standards are ASTM ACI andEN standards203 Compressive strength shall always be specified in addition tensile strength Youngrsquos modulus (E-modulus) and fracture energy may be specified Properties which can cause cracking of structural concrete shallbe accounted for ie creep shrinkage heat of hydration thermal expansion and similar effects The durabilityof structural concrete is related to permeability absorption diffusion and resistance to physical and chemicalattacks in the given environment A low watercement-binder ratio is generally required in order to obtainadequate durability The concrete shall normally have a watercement-binder ratio not greater than 045 In thesplash zone this ratio shall not be higher than 040

204 If pozzolanic or latent hydraulic additions are used in the production of concrete in combination withPortland cement or Portland composite cement these materials may be included in the calculation of aneffective watercement (WC) binder ratio The method of calculation of effective WC ratio shall bedocumented205 The durability of structural concrete shall be related to permeability and resistance against physical andchemical attacks

Guidance noteTo protect the reinforcement against corrosion and to give the concrete sufficient durability the coefficient ofpermeability of concrete should be low (10-12 to 10-8 msec) The test shall be carried out in accordance with relevantACI ASTM EN or ISO standardThis is normally obtained by use of

mdash Sound and dense aggregatesmdash Proper grading of fine and coarse aggregatesmdash Rich mixes with a minimum cement content of 300 kgm3

mdash Low water-cement ratio ie not greater than 045mdash Good concreting practice and workmanship ensuring adequate workability proper handling transportation

placing and consolidation and no segregation

206 Concrete subjected to freezing and thawing shall have adequate frost resistance This requirement maybe considered to be satisfied if the air content in the fresh concrete made with natural aggregates is at least 3for a maximum particle size of 40 mm or at least 5 for a maximum particle size of 20 mm The air poresshould be evenly distributed with a calculated spacing factor not exceeding 025 mm207 To improve the resistance against attacks from salts in the seawater cement with a moderate C3A contentmay be used see B200208 The total chloride ion content of the concrete shall not exceed 010 of the weight of cement in ordinaryreinforced concrete and in concrete containing prestressing steel209 In the splash zone the cement content shall not be less than 400 kgm3 For reinforced or prestressedconcrete not within the splash zone the cement content is dependent on the maximum size of aggregate asfollows

mdash up to 20 mm aggregate requires a minimum cement content of 360 kgm3

mdash from 20 mm to 40 mm aggregate requires a minimum cement content of 320 kgm3

mdash from 40 mm and greater the minimum required cement content shall be established by appropriate testing

210 The concrete grades are defined as specified in C300 The properties of hardened concrete are generallyrelated to the concrete grade For concrete exposed to sea water the minimum grade is C35 For concrete whichis not directly exposed to the marine environment the concrete grade shall not be less than C25 Prestressedreinforced concrete structures shall not be designed with concrete grade less than C30211 Where lightweight aggregates with a porous structure is used the mean value of oven dry (105degC)density for two concrete specimens after 28 days shall not deviate by more than 50 kgm3 from the requiredvalue Any individual value shall not deviate by more than 75 kgm3 The mean value for the entire productionshould lie within +20 kgm3 to -50 kgm3

212 If the water absorption of the concrete in the final structure is important this property shall be determinedby testing under conditions corresponding to the conditions to which the concrete will be exposed

C 300 Concrete characteristic strength 301 For concrete the 28 days characteristic compressive strength fcck is defined as the lower 5th percentilefound from statistical analysis of tests on cylindrical specimens with diameter 150 mm and height 300 mm 302 The normalized in-situ compression strength fcn of normal weight concrete shall be determined fromthe following formula for concrete with concrete grade between C25 and C90

fcn = fcck middot (1-fcck600)where

fcck = characteristic concrete compressive cylinder strength in Table C1γm = the material factor of concrete in accordance with Table C1 in Section 6

303 The characteristic tensile strength ftk of the material shall be determined as the 50 quantile in theprobability distribution of the strength data The characteristic strength data shall be estimated with at least 75confidence304 The normalized in-situ tensile strength ftn of normal weight concrete shall be determined from thefollowing formula for concrete with concrete grade between C25 and C90

ftn = ftk middot (1-(ftk25)06)

where

ftk = 048 (fcck)05

ftk may alternatively be determined in accordance with the provisions in C312 or C313

305 A factor (1-fcck600) is applied on the characteristic compression cylinder strength fcck and considerstransition of cylinder strength into in-situ strength ageing effects due to high-sustained stresses etc

306 Normal weight concrete has grades identified by C and lightweight aggregate concrete grades areidentified by the symbol LC The grades are defined in Table C1 and Table C2 as a function of the characteristiccompression cylinder strength of concrete fcck

307 The strength values given in Table C2 apply to lightweight aggregate concrete with the followinglimitations and modifications

Unless tensile strength is determined by testing tensile strength ftk and normalized in-situ strength ftn oflightweight aggregate concrete shall be multiplied by the factor η equal to (015 + 085 ρ ρ1) as shown inTable C2

For lightweight aggregate concrete with intended concrete strength fcck gt fcck3 (ρ ρ1)2 it shall be shown bytest samples that a characteristic strength 15 higher than the intended can be achieved The tests shall becarried out on concrete samples using the same material composition as intended

In the above

fcck2 = 94 MPafcck3 = 64 MPaρ = Density of the lightweight concreteρ1 = 2200 kgm3

308 Prior to using non-standard lightweight concrete mixes in a structure or barge the properties of the mixshall be documented for suitability for the intended application The following properties of the lightweightconcrete or lightweight composite concrete shall be documented as a minimum

mdash Workabilitymdash Densitymdash Youngrsquos Modulus

Table C1 Properties for normal weight (NW) concrete gradesConcrete grade C25 C30 C35 C40 C45 C50 C55 C60 C70 C80 C90

fcck [MPa] 1) 25 30 35 40 45 50 55 60 70 80 90fcn [MPa] 2) 240 285 330 373 416 458 500 540 618 693 765ftk [MPa] 3) 240 263 284 304 322 339 356 372 402 429 455ftn [MPa] 4) 181 195 207 218 228 237 245 253 268 280 2911) fcck = characteristic cylinder compressive strength 2) fcn = normalized in-situ compression strength3) ftk = characteristic mean tensile strength 4) ftn = normalized in-situ tensile strength

Table C2 Properties for lightweight aggregate concrete (LWA) gradesConcrete grade LC25 LC30 LC35 LC40 LC45 LC50 LC55 LC60 LC70 LC80

fcck [MPa] 1) 25 30 35 40 45 50 55 60 70 80fcn [MPa] 2) 240 times η 285 times η 330 times η 373 times η 416 times η 458 times η 500 times η 540 times η 618 times η 693 times ηftk [MPa] 3) 240 times η 263 times η 284 times η 304 times η 322 times η 339 times η 356 times η 372 times η 402 times η 429 times ηftn [MPa] 4) 181 times η 195 times η 207 times η 218 times η 228 times η 237 times η 245 times η 253 times η 268 times η 291 times η1) fcck = characteristic cylinder compressive strength 2) fcn = normalized in-situ compression strength3) ftk = characteristic mean tensile strength4) ftn = normalized in-situ tensile strengthη = (015 + 085 ρ ρ1) where according to ρ1 = 2200 kgm3 ρ = Density of the lightweight concrete

2

12

le

ρρ

cckcck ff

mdash Durabilitymdash Characteristic compression cylinder strength fcck (based on 150 times 300 mm cylinders)mdash ftk the characteristic tensile strength (see C312 and C313 below)mdash Fatigue strength parameter C5 of the concrete The factor C5 determines the relationship between static

reference strength frd and fatigue reference strength frd fat The relationship is determined as frdfat = C5 middot frd Reference is made to Sec6 M200

mdash In some cases it may be appropriate to document the properties and characteristics of the lightweightaggregate especially its durability and reactivity for application in the marine environment

Guidance noteS-N curves shall be presented in a format compatible with S-N curves for concrete as presented in Sec6 M200 in orderto use the provisions for design for Fatigue Limit State in this standard

309 For normal density concrete of grade higher than C60 and lightweight aggregate concrete of all gradesit shall be documented by testing that the concrete satisfies the requirements on the characteristic compressivecylinder strength

310 For concrete at high temperatures for a short period (fire) it may be assumed provided more accuratevalues are not known that the compressive strength reduces linearly from full value at 350degC to zero at 800degCThe tensile strength may be assumed to decrease from full value at 100degC to zero at 800degC If the concrete isexposed to temperatures above 200degC for a longer period of time the strength properties of the concrete shallbe based on test results

311 For concrete exposed to temperatures below -60degC the possible strength increase in compressive andtensile strength may be utilized in design for this conditions provided the strength are determined from relevanttests under same conditions (temperature humidity) as the concrete in the structure An increase in tensilestrength of concrete caused by low temperatures will generally tend to increase the distance between the crackshence increase the crack widths

312 The characteristic tensile strength of the concrete ftk may be determined by testing of the splittingtensile strength for cylindrical specimens at 28 days in accordance with EN 12390-6 or ISO 1920-4 Thecharacteristic tensile strength ftk shall be taken as 08 of the characteristic splitting strength determined bytesting

Guidance noteThe reference cylinder size to find the characteristic splitting strength for use with this standard shall be taken as150 times 300 mm Tests conducted on other specimen sizes should be accompanied by a conversion factor to convert theresults to those of 150 times 300 mm cylinders

313 The characteristic tensile strength of the concrete ftk may be determined by determining the modulus ofrupture by the testing of the unreinforced beams at 28 days in accordance with ASTM ACI or EN standardsThe characteristic tensile strength ftk shall be taken as 06 of the characteristic modulus of rupture determinedby testing

Guidance noteWhen deriving the characteristic modulus of rupture value the four point loading set up shall be taken as the referencetest set up It has been shown that testing conducted using a three point bending method yields results 13 higher thanthe four point bending set up If the three point method is employed the resulting characteristic modulus of rupturevalue shall be adjusted accordingly

314 The normalized Youngrsquos modulus of concrete is controlled by the Youngrsquos modulus of its componentsApproximate values for the Youngrsquos modulus Ecn is taken as the secant value between σc = 0 and 04 fcckApproximate values for quartzite aggregates may be determined from the following formulation

Ecn = 22 000 middot (fcck10)03 MPa

For limestone and sandstone aggregates the value should be reduced by 10 and 30 respectively For basaltaggregates the value should be increased by 20

315 For rehabilitation or for verifying the capacity in structures where the concrete strength is unknown thestrength shall be determined on the basis of drilled core specimens taken from the structure

The extent of testing shall be chosen so that it gives a satisfactory knowledge of the strengths in the structuralmembers to be examined

Provided the smallest dimension is not less than 40 mm the following specimen scaling factor can be used inpredicting the cylinder strength

The cylinder strength in the structure is obtained by multiplying the results from drilled cores with theappropriate scaling factor based on the height diameter ratio of the test specimen

The concrete is considered to satisfy the requirements to characteristic strength given in Table C1 and Table C2 provided the characteristic value of the cylinder strength in the structure is at least 85 of the requiredcharacteristic strength for cylinders for assumed strength class shown

For concrete specimens that have gained at least the 28 days strength the (equivalent) characteristic cylinderstrength fcck used in the design may be taken as

fcckt = 300 - 10 middot (900 - 6 middot fcckj)05

where

fcckj is the characteristic strength of the taken specimens converted into cylinder strength for cylinders withheightdiameter ratio 21

fcckt is the characteristic compressive cylinder strength at 28 days based on in-situ tests

For design fcckt replaces fcck the characteristic concrete compressive strength in Table C1 and Table C2

D Fibre Reinforced Concrete

D 100 Material requirements of fibre reinforced concrete

101 The constituent materials of fibre reinforced concrete are cement fine sand aggregates wateradmixtures and short fibre material mixed to get a uniform matrix The fibres may either be made of steel orFRP

102 The normalized Youngrsquos modulus of fibre reinforced concrete is controlled by the Youngrsquos modulus ofits components Approximate values for the Youngrsquos modulus Ecn is taken as the secant value between σc = 0and 04 fcck

Guidance noteApproximate values for fibre reinforced concrete with quartzite aggregates may be determined from the followingformulation

Ecn = 22 000 middot (fcck10)03 MPaFor limestone and sandstone aggregates the value should be reduced by 10 and 30 respectively For basaltaggregates the value should be increased by 20

103 The workability and quality of the mixed fibre reinforced concrete depends on the amount and length ofthe fibres in the mix The workability and quality of the fibre reinforced concrete shall be documented prior touse

Guidance noteAs a guideline the max length of the fibre should be 60 mm and the maximum amount of fibres 2 by volume

104 The fibres shall be of sufficient length to provide bond between the concrete matrix and the fibres Guidance noteAs a guideline the minimum length of the fibre should be 30 mm The minimum length of the fibre should also belarger than three times the maximum aggregate size

105 The concrete material in fibre reinforced concrete shall be in accordance with C100 and C200

106 The characteristic concrete compressive cylinder strength fcck of the material shall be determined as the5 quantile in the probability distribution of the strength data The characteristic strength data shall beestimated with at least 75 confidence

107 fcck shall be determined on standard cylinders of size 300 middot 150 mm tested in accordance with arecognized standard (ASTM ACI or EN)

108 The characteristic tensile strength ftk of the material shall be determined as the 50 quantile in theprobability distribution of the strength data The characteristic strength data shall be estimated with at least 75confidence

Table C3 Scaling factor on drilled core resultsHeightdiameter ratio 200 175 150 125 110 100 075Scaling factor on strength values 100 097 095 093 089 087 075

109 The characteristic tensile strength ftk may be determined from converting the characteristic tensilestrength from splitting tests or from modulus of rupture tests to direct tensile strength

Guidance noteThe conversion factor to obtain the characteristic tensile strength is 08 on the characteristic splitting tests and 06 onthe characteristic modulus of rupture strength The characteristic strength is defined in D108The reference cylinder size to find the characteristic splitting strength for use with this standard shall be taken as150 times 300 mm Tests conducted on other specimen sizes should be accompanied by a conversion factor to convert theresults to those of 150 times 300 mm cylindersWhen deriving the characteristic modulus of rupture value the four point loading set up shall be taken as the referencetest set up It has been shown that testing conducted using a three point bending method yields results 13 higher thanthe four point bending set up If the three point method is employed the resulting characteristic modulus of rupturevalue shall be adjusted accordingly

110 The characteristic tensile strength of fibre reinforced concrete will increase as a function of thevolumetric percentage of fibres mixed into the concrete The tensile strength increases more for steel fibres thanFRP fibres For both cases it is a precondition that the fibres are mixed uniformly through the concrete

The following guidelines with respect to increase in the characteristic tensile strength ftk may be used initiallyin a project until the actual direct tensile strength is known

Guidance noteFor steel fibres As a guideline ftk may be obtained from the following equation

ftk = (048 + 01 middot v) middot (fcck)05 where v = volumetric percentage of steel fibre in the concrete mix

For FRP fibres As a guideline ftk may be obtained from the following equationftk = (048 + 005 middot v) middot (fcck)05

where v = volumetric percentage of FRP fibre in the concrete mix

111 The characteristic concrete cylinder compression strength fcck is generally not affected by the inclusionof fibres (steel or FRP) in the concrete Fibre reinforced concrete performs in a more ductile way than concretewithout fibres

112 The normalized compression strength fcn of fibre reinforced concrete may be determined from thefollowing formula

fcn = fcckmiddot (1-fcck600)

where

fcck = characteristic concrete cylinder strength of the fibre reinforced concrete

The factor (1-fcck600) is applied on the characteristic compression cylinder strength fcck and considerstransition of cylinder strength into in-situ strength brittleness ageing effects due to high sustained stresses etc

113 The normalized tensile strength ftn of normal weight fibre reinforced concrete may be determined fromthe following formula for concrete with concrete grade between C35 and C90

114 Prior to using fibre reinforced concrete in a structure the composite concrete mix shall be documentedfor suitability for the intended application The following properties of the fibre reinforced concrete shall bedocumented as a minimum

mdash Workabilitymdash Youngrsquos Modulusmdash Characteristic compression cylinder strength of the fibre reinforced concrete fcckmdash ftk the characteristic tensile strength of the fibre reinforced concrete (see D109 and D110 above)mdash Fatigue strength parameter C5 of fibre reinforced concrete The factor C5 determines the relationship

between static reference strength frd and fatigue reference strength frd fat The relationship is determinedas frdfat = C5 middot frd Reference is made to Sec6 M200

mdash The concrete material itself without fibre shall be documented in accordance with the general requirementsfor concrete in C

115 Static shear strength may increase due to the addition of fibre and the associate increased tensile strengthThis possible increase in shear strength shall also be documented for the fibre reinforced concrete member Thesame type length volume and quality of fibre shall be used in the test The tests shall be carried out on beamsunder two point loadings

Guidance noteThe test specimen shall have a minimum dimension of h = 200 mm b = 100 mm where h and b are the depth andwidth respectively of the specimen The length of the specimen shall be minimum 1350 mm and the shear span aminimum 500 mm ie ah gt 25 The concrete specimen shall be reinforced with longitudinal steel reinforcementThe purpose of this test is to verify the contribution of the tensile strength of the fibre reinforced concrete into theshear strength formula in Sec6 F200 based on ftk and the design metrology method in this standard

116 The same material factors shall apply to fibre reinforced concrete as ordinary concrete117 The durability of the fibres for the application shall be documented Steel fibre reinforced concrete shallnot be used in the concrete cover zone and exposed to environmental classes XD2 XS2 XF1 and XA1 orhigher FRP fibres are resistant for corrosion The FRP fibres shall be documented for durability when exposedto marine environment118 Crack width predictions depend on the tensile strength of concrete The higher the tensile strength thelonger the distance is between cracks and the wider the crack width becomes Beams tests shall be carried outto document the relationship between crack width and tensile strength for the actual fibres to be used

E Structural Grout

E 100 Material requirements101 The constituents of grout are cement water and often admixtures fine aggregates may also be includedThese shall meet the same requirements as those given in B Structural grout in this standard shall have acharacteristic compressive strength higher than 35 MPa Structural grout may be pre-packed blended or neatcement grout102 The normalized Youngrsquos modulus of structural grout is controlled by the Youngrsquos modulus of itscomponents Approximate values for the Youngrsquos modulus Ecn is taken as the secant value between σc = 0and 04 fcck

Guidance noteApproximate values for structural grout quartzite aggregates may be determined from the following formulation

103 All grout constituent materials shall be proportioned by mass except the mixing water which mayalternatively be proportioned by volume The watercement ratio shall not be higher than 045

Guidance noteThe proportioning of site-batched grout should be within an accuracy of 2 for cement and admixtures and 1 forwaterGrout intended for use in the marine environment should have a minimum cement content of 600 kgm3

104 Maximum aggregate size shall be specified based on the intended application for example space inbetween forms and placing method (size of the hose pumping head etc)105 The in-place properties of the grout material shall be documented by appropriate large scale test setups(mock-up tests) in advance of the grouting operation The test-setup shall reflect the actual conditions andequipment at the site including a realistic typical hose diameter and length to assess pumpability of the material

Further if contingency procedures involve other grout placement configurations these shall be reflected in thetest setups Full filling of the intended volume shall be demonstrated and documented

Guidance noteIt is of high importance that the structural grout has volumetric stability in order to fill the intended volume as highautogenous andor drying shrinkage in the grout will reduce the load capacity of the structural element Assessmentof volumetric stability should therefore be documented prior to commencement of operations

106 The grout mix used for injection in prestressing ducts shall be designed for the specified properties whichshall at least include fluidity and bleeding (in the plastic condition) autogenous shrinkage and compressivestrength (in hardened condition)

107 The properties of structural grout shall be documented on a Material Certificate defining at least thefollowing limitations and properties

mdash Main operational limitations qualified temperature for grout application thickness range pumping lengthrange and elevation head for specific hose diameter

mdash General properties density flowability setting time (initial and final) air content stability etc mdash Mechanical properties shrinkage creep characteristic compressive cylinder strength Youngrsquos modulus

Poissonrsquos ratio and splitting tensile strength or modulus of rupture (according to ASTM or EN) In all casesmean value standard deviation and number of samples tested shall be reported If property evolution withtime and temperature is of interest for the intended application this shall be documented

mdash Fatigue strength parameter C5 of the grout determines the relationship between static reference strengthfrd and fatigue reference strength frd fat The relationship is determined as frd fat = C5 middot frd Reference ismade to Sec6 M200

For a complete list of required content see Appendix H Guidance noteS-N curves shall be presented in a format compatible with S-N curves for concrete as presented in Sec6 M in orderto use the provisions for design for Fatigue Limit State in this standard

108 The characteristic compression cylinder strength fcck shall be determined as the 5 quantile in theprobability distribution of the strength data The characteristic strength data shall be estimated with at least 75confidence

Guidance noteAs a guideline ftk can be obtained from the following equation

ftk = 048 middot (fcck)05

Guidance noteThe conversion factor to obtain the characteristic tensile strength is 08 on the characteristic splitting tests and 06 onthe characteristic modulus of rupture strength The characteristic strength is defined in E109The reference cylinder size to find the characteristic splitting strength for use with this standard shall be taken as150 times 300 mm Tests conducted on other specimen sizes should be accompanied by a conversion factor to convert theresults to those of 150 times 300 mm cylindersWhen deriving the characteristic modulus of rupture value the four point loading set up shall be taken as the referencetest set up It has been shown that testing conducted using a three point bending method yields results 13 higher thanthe four point bending set up If the three point method is employed the resulting characteristic modulus of rupturevalue shall be adjusted accordingly

111 In cases where on-site QC samples are cast from cubes or cylinders smaller than those used to define thecharacteristic compressive strength a conversion factor between the QC specimens and the standard testcylinders shall be determined This is a requirement for using different QC-specimens for offshore projects

112 The normalized compression strength fcn of structural grout shall be determined from the followingformula

fcn = fcck middot (1-fcck600)

where

fcck = characteristic concrete cylinder compression strength of the structural grout

The factor (1-fcck600) is applied on the characteristic compression cylinder strength fcck and considerstransition of cylinder strength into in-situ strength brittleness ageing effects due to high-sustained stresses etc

113 The normalized tensile strength ftn of structural grout shall be determined from the following formula

114 Appendix I provides guidelines on QAQC systems for the manufacturing of Structural Grout

115 For requirements to general grouting operations see Sec7 Q

E 200 Pre-packed blended grout

201 Pre-packed and blended structural grout shall be tested and delivered in accordance with a standardrecognized in the place of use Recognized relevant standards are ASTM ISO and EN Recommended testingfor fresh and hardened grout is given in Appendix H

202 Pre-packed blended grout shall be delivered with a Material Certificate stating at least the limitations andproperties specified in Appendix H

203 The grout manufacturer shall have a quality system in operation that accounts for the requirements in thissection and ensures full traceability of the grout manufacture The responsibility for operation of the qualitysystem shall be with one dedicated person at the manufacturing site

204 The extent of production testing shall be sufficient to confirm compliance of the as-produced grout withthe Material Certificate

205 The plan for the tests during production shall be specified by the grout manufacturer and included in theQA system of the manufacturing plant the QA system shall as a minimum include the requirements specifiedin Appendix I

F Fibre Reinforced Structural Grout

F 100 Material requirements for fibre reinforced structural grout

101 The constituent materials of fibre reinforced grout are cement fine aggregates water admixtures andshort fibre material mixed to get a uniform matrix The short fibre material may either be made of steel or FRPFibre reinforced structural grout in this standard shall have a characteristic compressive strength higher than35 MPa Fibre reinforced structural grout may be pre-packed blended or neat cement grout

102 The normalized Youngrsquos modulus of fibre reinforced grout is controlled by the Youngrsquos modulus of itscomponents Approximate value for the Youngrsquos modulus Ecn is taken as the secant value between σc = 0 and04 fcck

Guidance noteApproximate values for fibre reinforced grout may be determined from the following formulationEcn = 22 000 middot (fcck10)03 MPa

103 The workability and quality of mixing the fibre reinforced grout depend on among other properties theamount and length of fibres in the mix The workability and quality of the fibre reinforced grout shall bedocumented prior to use

104 The fibres shall be of sufficient length to provide bond between the grout matrix and the fibres Guidance noteAs a guideline the minimum length of the fibre should be 20 mm The minimum length of the fibre should also belarger than three times the maximum aggregate size

105 The grout material in fibre reinforced grout shall be in accordance with the requirements in E100 andE200

107 fcck shall be determined on water cured standard cylinders of size 150 mm diameter and 300 mm hightested in accordance with a recognized standard (ASTM ACI or EN)

Guidance noteThe conversion factor to obtain the characteristic tensile strength is 08 on the characteristic splitting tests and 06 onthe characteristic modulus of rupture strength The characteristic strength is defined in F108

The reference cylinder size to find the characteristic splitting strength for use with this standard shall be taken as150 times 300 mm Tests conducted on other specimen sizes should be accompanied by a conversion factor to convert theresults to those of 150 times 300 mm cylindersWhen deriving the characteristic modulus of rupture value the four point loading set up shall be taken as the referencetest set up It has been shown that testing conducted using a three point bending method yields results 13 higher thanthe four point bending set up If the three point method is employed the resulting characteristic modulus of rupturevalue shall be adjusted accordingly

110 The characteristic cylinder compression strength of the grout is generally not affected by the inclusionof fibres (steel or FRP) in the grout Fibre reinforced grout will perform in a more ductile way than groutwithout fibres111 The characteristic tensile strength of fibre reinforced grout will increase as a function of the volumetricpercentage of fibres mixed into the grout The tensile strength increases more for steel fibres than FRP fibresFor both cases it is a precondition that the fibres are mixed uniformly through the groutThe following guidelines with respect to increase in the characteristic tensile strength ftk may be used initiallyin a project until the actual direct tensile strength is known

Guidance noteFor steel fibresAs a guideline ftk may be obtained from the following equationftk = (048 + 01 middot v) middot (fcck)05 where v = volumetric percentage of steel fibre in the grout mix

For FRP fibresAs a guideline ftk may be obtained from the following equationftk = (048 + 005 middot v) middot (fcck)05 where v = volumetric percentage of FRP fibre in the grout mix

112 The normalized compression strength fcn of fibre reinforced grout may be determined from thefollowing formula

fcck = characteristic grout cylinder strength of the fibre reinforced grout

The factor (1-fcck600) is applied on the characteristic compression cylinder strength fcck and considerstransition of cylinder strength into in situ strength brittleness ageing effects due to high-sustained stresses etc113 The normalized tensile strength ftn of fibre reinforced grout shall be determined from the following formula

ftn = ftk middot (1-(ftk25)06)114 Prior to using fibre reinforced grout in a structure the composite grout mix shall be documented forsuitability for the intended application and be delivered with a Material Certificate The following propertiesof the grout shall be documented as a minimum

mdash The grout material without fibres shall be documented in accordance with the requirements in E100

For a complete list of required content see Appendix H 115 The durability of the fibres shall be documented for the application in question FRP fibres are resistantto corrosion however the durability of FRP fibres shall be documented when exposed to a marine environment Steel fibre reinforced grout shall not be used in the cover zone of structures reinforced with steel reinforcementThe durability of steel fibre reinforced grout exposed to environmental classes XD2 XS2 XF1 XA1 or higherin grouted connections clamps etc shall be documented116 Static shear strength may increase due to the addition of fibres and increased tensile strength This

possible increase in shear strength shall also be documented for the fibre reinforced grout member The sametype length volume and quality of fibre shall be used in the test

117 Crack width predictions depend on the tensile strength of grout The higher the tensile strength the longerthe distance is between cracks and the wider the crack width becomes Two points beam tests shall be carriedout to document the relationship between crack width and tensile strength for the actual fibre to be used

118 Appendix I provides guidelines on QAQC systems for the manufacturing of Structural Grout theserequirements shall also apply to the manufacturing of fibre reinforced grout

F 200 Pre-packed blended grout with fibres

201 Pre-packed blended grout with fibres shall be tested and delivered in accordance with a standardrecognized in the place of use Recognized relevant standards are ASTM ISO and EN Recommended testingfor fresh and hardened grout is given in Appendix H

202 Pre-packed blended structural grout with fibres shall be delivered with a Material Certificate stating atleast the limitations and properties See Appendix H

G Steel Reinforcement

G 100 General

101 Reinforcement shall be suitable for its intended service conditions and have adequate properties withrespect to strength ductility toughness weldability bond properties (ribbed) corrosion resistance and chemicalcomposition These properties shall be specified by the supplier or determined by recognized test methods

102 Reinforcing steel shall comply with ISO 6935 Parts 2 and 3 or relevant international standards forreinforcing steel

103 Consistency shall be ensured between material properties assumed in the design and requirements of thestandard used In general hot-rolled ribbed bars of weldable quality and with high ductility shall be usedWhere the use of seismic detailing is required the reinforcement provided shall meet the ductility requirementsof the reference standard used in the design

104 Reinforcement steel shall be delivered with a Worksrsquo Certificate The requirement for a WorksrsquoCertificate may be waived if the reinforcement is produced and tested under a national or internationalcertification scheme and all the required test data are documented based on statistical data from the producerAll steel shall be clearly identifiable

105 Galvanised reinforcement may be used where provisions are made to ensure that there is no adversereaction between the coating and the cement which would have a detrimental effect on the bond to thegalvanised reinforcement

106 Stainless steel may be used provided the requirements to mechanical properties for ordinary reinforcingsteel are met

107 Epoxy coated reinforcement may be used provided the requirements to mechanical properties forordinary reinforcing bars are met

108 Tempcore reinforcement may be used provided the requirements to mechanical properties for ordinaryreinforcing bars are met

G 200 Mechanical splices and end anchorages for reinforcement

201 Anchorage devices or couplers shall comply with national standards and be as defined in the projectspecification Fatigue properties and S-N curves shall be consistent with the assumptions of the design and bedocumented for the actual combinations of rebars couplers or end anchorages

202 Mechanical splices and end anchorages shall be delivered with a Product Certificate

203 Friction welded end anchorages on rebars (T-heads) shall be qualified tested in advance with the actualtype of rebar and be routinely tested during production The test program shall include a tension test and a bendtest to document strength and ductility of the connection The friction weld shall not fail before the rebar

G 300 Approval of welding procedures301 Welding procedures together with the extent of testing for weld connections relevant to reinforcedconcrete and concrete structures shall be specified and approved in each case

G 400 Steel reinforcement characteristic strength 401 For reinforcement steel the characteristic strength fyk is determined as the 5 defective fractile402 For the fatigue limit state (FLS) the characteristic SN-curve shall be determined statistically as a 25defective fractile for reinforcement couplers welded connections etc unless other values are specified in thereference standard for that design

H Steel Prestressing Reinforcement

H 100 General101 Prestressing steel as a product shall comply with ISO 6934 andor relevant International standards forprestressing steel102 Prestressing steel shall be delivered with a Worksrsquo Certificate103 The fatigue properties (S-N curves) for the prestressing steel shall be documented104 For use in the marine environment possible negative effects of the marine environment on the fatiguestrength shall be accounted for in the Woumlhler curves

H 200 Components for the prestressing system201 Tendons (wires strands bars) anchorage devices couplers and ducts or sheaths are part of a prestressingsystem described in the project specification All parts shall be compatible and clearly identifiable202 Prestressing systems shall comply with the requirements of project specifications by design and shallhave the approval of an authorized institution or the national authority203 Sheaths for post-tensioning tendons shall in general be of a semi rigid or rigid type water tight and withadequate stiffness to prevent damages and deformations The ducts shall be of steel unless other types arespecified by design204 Components for the prestressing system shall be delivered with a Product Certificate 205 Fatigue properties (S-N curves) for the complete assembly system shall be documented206 Parameters needed to calculate friction losses between the prestressing steel and the ductssheathsanchorage loss and steel relaxation shall be documented

H 300 Steel prestressing reinforcement characteristic strength 301 For prestressed reinforcement the characteristic strength is equal to the yield strength fsy or the 01-proofstress determined as the 5 defective fractile302 For the fatigue limit state FLS the characteristic SN-curve shall be determined statistically as a 25defective fractile for reinforcement prestressing assemblies couplers etc unless other values are specified inthe reference standard for that design

I FRP Reinforcement

I 100 General101 The scope of the provisions for FRP materials in this standard is limited to bars of carbon glass aramidor basalt fibre reinforced composites102 The requirements in this section do not cover subsequent machining assembly into semifinishedproducts such as nets or cages and issues regarding construction on site such as storage and handling of thebars assembly of reinforcement and casting of the concrete103 FRP reinforcement bars shall be suitable for the intended service conditions and shall have adequateproperties with respect to strength elongation to break time to rupture fatigue toughness bond propertiesalkali resistance and chemical composition These properties shall be determined by a recognized test methodand specified by the supplier Testing requirements are given in N1100104 Consistency shall be ensured between bar properties assumed in the design and requirements of thestandard used In general FRP bars shall be used with the load bearing fibres oriented predominantly in thelongitudinal direction of the bars and with a cross section that varies such as to provide interlocking in theconcrete and a surface that provides adequate bonding to the concrete105 FRP bars shall be delivered with a Material Certificate The parameters to be shown on the MaterialCertificate are specified in Appendix F All bars shall be clearly identifiable

106 Coated reinforcement may be used provided the requirements to mechanical properties for ordinaryreinforcing bars are met the effect of the coating on bonding is documented and the coating process is coveredby the QAQC system of the bar manufacturer

107 Main sub-contractors and raw material suppliers of the bar manufacturer should operate a quality systemthat is formally accepted by the bar manufacturer

108 The bar manufacturer shall have a quality system in operation that accounts for the requirements in thissection and ensures full traceability of the bar manufacture The responsibility for operation of the qualitysystem shall be with one dedicated person at the manufacturing site

109 Appendix G provides guidelines on QAQC systems for the manufacturing of FRP bars

I 200 Mechanical splices and anchorages for FRP reinforcements

201 Anchorage and splicing arrangements shall be restricted to types that have been qualified for the bar typeand dimension in question

202 Mechanical splices and end anchorages for FRP bars shall be delivered with a Product Certificate

I 300 FRP prestressed bars

301 FRP reinforcing bars can be used as prestressing bars in reinforced concrete structures The prestressingmay be either a pre-tensioning system or a post-tensioning system

302 The capacity and service behaviour of prestressed FRP systems can be handled in a similar way as forprestressed steel systems ie by applying a normal compression force and a moment in case the prestressingis applied eccentric in the section This applies both for flexural capacity predictions shear strength predictionsdeflection calculation and crack width calculations

303 Due consideration shall be given to the consequences of the differences between Youngrsquos modulus ofFRP and steel on the anchorage shrinkage and creep losses

Guidance noteGenerally FRP has a lower Youngrsquos Modulus than steel and consequently is less sensitive to anchorage shrinkageand creep losses than steel tendons

304 In calculation of moment capacity of FRP pre-stressed members the strainstress change in the FRPreinforcement caused by external loading shall be included in the internal force and moment calculation andthe stress in the FRP reinforcement shall not exceed the permissible stress according to the load combinationsspecified in Sec5 D

305 For pre-tensioned systems the FRP bars can be pre-stressed to required level in accordance withSec6 O900 Following hardening of the concrete and development of sufficient bond strength the FRPreinforcement can be cut in normal manner and the pre-tensioning is transferred to the concrete member

306 The post-tension systems shall be grouted as otherwise required for post-tensioning using steel tendonsThe ducts shall be of a non-corrosive material and suitable for transferring the forces between the FRPreinforcement and the surrounding concrete

307 For post-tension systems the tensioning system gripping methods may damage the FRP reinforcementGenerally the tensioning stress level is relatively low compared to the short term strength of the FRPreinforcement Post-tensioning system shall be proven The post-tensioning anchorage system shall bedocumented for the post-tensioning level to be applied and shall be made from non-corrosive material ifexposed to a corrosive environment

I 400 FRP reinforcement characteristic strength

401 The properties of the FRP bars shall be documented by relevant recognized tests As a minimum thetesting described in N1100 shall be performed Strength and stiffness values shall be represented in terms ofcharacteristic values

402 Characteristic bar properties for use in design shall be determined in advance from tests on specimensrepresentative of continuous production and specified in the Material Certificate or in a data-sheet attached withthe Material Certificate

Guidance noteThe coefficient of variation used for design should be assumed with care It is advisable to assume a conservativelarge value to make sure that variations that may occur in production but are not reflected in the tested sample areaccounted for

403 The characteristic strength of FRP bars is equal to the characteristic short term strength of FRP barswhich shall be defined the as the lower 5th percentile with 75 confidence level from the sample mean andstandard deviation of strength data from tests on a representative sample of specimens

404 The characteristic time to rupture curve of FRP bars shall also be defined as the lower 5th percentile with75 confidence level from the sample mean and standard deviation of life data from tests on a representativesample of specimens405 The design temperatures are reference temperatures representing the intended use The standardreference temperature is room temperature (20-23degC) Material factors determined from test data obtained atroom temperature shall be modified by the application of temperature conversion factors ηT determinedthrough testing at relevant temperatures

Guidance noteηT may be assumed to be equal to 10 for application in the temperature range from -20degC to 20degC ηT shall bedetermined for the full range of application temperaturesFor intended service in tropical areas and for documentation of fire resistance a temperature representative of themaximum temperature that the FRP bars will be exposed to in the specified design conditions shall be used Thistemperature may account for measures taken to limit the temperature such as cooling measures implemented on sun-exposed surfaces cover thicknesses used and insulationfire protection applied For intended service in arcticconditions and cryogenic service an extreme low temperature shall be used Materials near heat-emitting systems(eg machinery parts etc) shall be able to withstand the local temperatures

406 The effect of concrete embedment alkali exposure bends etc shall be considered in determining thestrength of FRP bars according to N1100

J Steel Fibres

J 100 General101 Steel fibres which are used in concrete or grout shall be suitable for the application intended and providesufficient performance in concrete or grout

K FRP Fibres

K 100 General101 FRP fibres are produced by carbon glass basalt and aramid The FRP fibres shall be tested and foundsuitable for application in concrete structures It shall be documented that the fibre is durable in concretestructures exposed to the actual environmental conditions

L Embedded Materials

L 100 General101 Embedded materials such as steel and composites shall be suitable for their intended service conditionsand shall have adequate properties with respect to strength ductility toughness weldability laminar tearingcorrosion resistance and chemical composition The supplier shall document these properties

M Other Materials

M 100 Repair materials101 The composition and properties of repair materials shall be such that the material fulfils its intended useOnly materials with established suitability shall be used Emphasis shall be given to ensure that such materialsare compatible with the adjacent material particularly with regard to the elasticity and temperature dependentproperties102 Requirements for repair materials shall be subject to case-by-case consideration and approvalDeterioration of such materials when applied for temporary use shall not be allowed to impair the function ofthe structure at later stages103 The extent of testing of repair materials shall be specified in each case

M 200 Non-cementitious materials201 The composition and properties of non-cementitious materials shall be determined so that each materialfulfils its intended use Special emphasis shall be given to ensure that such materials are as similar as possibleto the adjacent material particularly in the sense of elasticity and temperature dependent properties Theirproperties shall be documented with respect to their intended application

M 300 Equivalent materials301 When using equivalent material based on experience the equivalence shall be documented Suchdocumentation shall as a minimum identify the main properties including project specific requirements andparameters affecting these It shall be demonstrated that the experience is relevant for all identified parameters

N Testing of Materials

N 100 Testing of freshly mixed concrete101 Requirements to the testing of freshly mixed concrete are given in Sec7 D and Sec7 F

N 200 Testing of concrete in the structure201 Requirements to the testing of concrete in structures are given in Sec7 F

N 300 Grout for prestressing tendons301 The requirements for testing of freshly mixed grout are given in Sec7 F

N 400 Pre-packed blended grout401 Pre-packed grout shall be delivered with a Material Certificate Recommended testing of fresh andhardened grout to document material properties is given in Appendix H 402 The requirements for ready mix grout production testing are given in Sec7 F

N 500 Reinforcement steel501 Reinforcement steel shall be delivered with a Worksrsquo Certificate See G104

N 600 Prestressing steel601 Prestressing steel shall be delivered with a Worksrsquo Certificate See H102

N 700 Mechanical splices for reinforcement701 Mechanical splices shall be delivered with a Product Certificate See G202 The certificate shalldocument that the mechanical splices are suitable for their intended application and have the same safety as thespliced reinforcement bars

N 800 Components for the prestressing system801 Components for the prestressing system shall be delivered with Products Certificate See H204 TheProduct Certificate shall document that the components for the prestressing system are suitable for theirintended application and have the same safety as the prestressing rods or tendons

N 900 Welding procedures901 Welding procedures together with the extent of testing (for weld connections relevant to reinforcedconcrete manufacture) shall be documented

N 1000 Testing of repair materials1001 The repair materials shall be documented in accordance with relevant recognised Internationalstandard ie ASTM ACI EN and ISO The repair materials shall be suitable for use in Offshore ConcreteStructures and have comparable properties to the parent material under repair The suitability of the repairmaterial shall be documented

N 1100 Testing of FRP materials1101 The bars shall be delivered with a Material Certificate specifying the properties required testing shallbe accordance with the requirements of Appendix F

SECTION 5LOADS AND ANALYSES REQUIREMENTS

A Requirements to Design

A 100 General

101 The engineering of a fixedfloating offshore concrete platform shall be performed in such a way that allfunctional and operational requirements relating to the safety of the installation and its operation are met aswell as those requirements relating to its functions as an offshore facility

102 The functional requirements will affect the layout of the structure thus influencing the loading scenariosthat shall be considered in the design of the structure The functional requirements shall be related to both thesite-specific conditions and the requirements of the platform as a production facility for production ofhydrocarbons and other activities associated with operations of a field

A 200 Site related functional requirements and environmental considerations

201 The platform shall be positioned and oriented on site such that it takes account of the reservoir otherplatforms governing wind and wave direction accessibility of ships and helicopters and safety in case of fireor leakages of hydrocarbons

202 There shall be a site-specific evaluation of all types of environmental conditions that can affect the layoutand design of the structure including rare events with a low probability of occurrence

203 The deck elevation shall be determined in order to give an adequate air gap based on site-specific dataallowing the passage of extreme wave crests higher than the design wave crest and taking due account ofpossible interacting ice or icebergs (if relevant) Interaction with deck supports and underwater caisson effectsshall also be considered

204 The water depth used in establishing layout and in the design shall be based on site-specific data takingdue account of potential settlements subsidence etc

A 300 Facility operational requirements

301 The functional requirements to be considered related to the productionoperational system are such as

a) layout of production wells risers and pipelines etc

b) storage volume compartmentation densities temperatures etc in case of stored products

c) safeguards against spillage and contamination

d) access requirements both internal and external for operation inspection and condition monitoring etc

e) interface to topsidesplant

f) installations for supply boats and other vessels servicing the platforminstallation

302 All hazard scenarios that can be associated with the operationsmaloperations and the functions of theplatform shall be established and evaluated such as fire explosions loss of intended pressure differentialsflooding leakages rupture of pipe systems dropped objects ship impacts etc The platforminstallation shallbe designed to give adequate safety to personnel and an adequate safety against damage to the structure orpollution to the environment

A 400 Structural requirements

401 Structures and structural members shall perform satisfactorily during all design conditions with respectto structural strength mooring stability ductility durability displacements settlements and vibrations Thestructure and its layout shall be such that it serves as a safe and functional base for all mechanical installationsthat are needed for the facility to operate Adequate performance shall be demonstrated in designdocumentation

402 Ground supported structures located in seismically active areas shall be designed to have adequatestrength to withstand the effects of an extreme level earthquake (ELE) as well as sufficient strength ductilityand energy dissipation capacity to remain stable during the rare motions of greater severity associated withabnormal level earthquake (ALE) The sufficiency of the structural strength ductility and energy dissipationcapacity shall be documented

The seismic ULS design event is the ELE The structure shall withstand an ELE event with little or no damageShutdown of production operations shalllerable and the structure should be inspected subsequent to an ELEoccurrence

The seismic ALS design event is the ALE The ALE is an intense earthquake of abnormal severity with a verylow probability of occurring during the structurersquos design service life The ALE can cause considerable damage

to the structure However the structure shall be designed such that overall structural integrity is maintained toavoid structural collapse causing loss of life andor major environmental damage

403 The structural concept details and components shall be such that the structure

a) has adequate robustness with small sensitivity to local damage

b) can be constructed in a controlled manner

c) provides simple stress paths that limit stress concentrations

d) is resistant to corrosion and other degradation

e) is suitable for condition monitoring maintenance and repair

f) remain stable in a damaged condition

g) fulfils requirements for removal if required

404 Full pollution control shall apply for oil containment structures This means that the oil containmentstructures shall be designed for no yield in the reinforcement for an ALS design event Reference is made toA704 Sec6 O310 and Sec6 O600

In order to ensure tightness the following criteria applies

mdash No yield (σs lt 09 fsk) for an ALS conditionmdash No pollution following a major ALS occurrence As an example the containment structure shall be

designed to meet the tightness requirements in Sec6 O600 for any load situation following an ALSoccurrence

405 In order to ensure corrosion control by limiting the strains in the reinforcement bars during temporarilyphases the requirements in A704 shall be implemented

A 500 Materials requirements

501 The materials selected for the load-bearing structures shall be suitable for the purpose The materialproperties and verification that these materials fulfil the requirements shall be documented Requirements tomaterials are given in Section 4

502 The materials all structural components and the structure itself shall be ensured to maintain the specifiedquality during all stages of construction The requirement to quality assurance is given in Section 4

A 600 Execution requirements

601 Requirements to execution testing and inspection of the various parts of the structure shall be specifiedon the basis of the significance (risk level) of the various parts with regard to the overall safety of the completedand installed structure as well as the structure in temporary conditions See Section 4 Section 7 and Section 8

A 700 Temporary phases requirements

701 The structure shall be designed for all stages with the same intended reliability as for the final conditionunless otherwise agreed This applies also for moorings or anchorage systems applied for stages of constructionafloat Reference is made to DNV Rules for the Planning and Execution of Marine Operations

702 For floating structures and all floating stages of the marine operations and construction afloat of fixedinstallations sufficient positive stability and reserve buoyancy shall be ensured Both intact and damagedstability should be evaluated on the basis of an accurate geometric model Adequate freeboard shall beprovided One-compartment damage stability should normally be provided except for short transient phasesThe stability and freeboard shall be in accordance with DNV-OSS-102 ldquoRules for Classification of FloatingProduction Storage and Loading Unitsrdquo

703 Weight control required for floating structures and temporary phases of fixed installations should beperformed by means of well-defined documented robust and proven weight control The system output shouldbe up to-date weight reports providing all necessary data for all operations

704 No permanent cracks caused by yield in the reinforcement shall occur during temporarily loadconditions This means that the stress in the reinforcement shall be less than 09 fsk for ULS combinationsapplying γF equal to 10 for all loads occurring during the temporarily phase See also Sec6 O310

B Design principles

B 100 General

101 The design shall be performed according to the limit state design as detailed in DNV-OS-C101 Section 2The design shall provide adequate strength and tightness in all design situations such that the assumptions madeare complied with This may be achieved by at least the following

mdash design of concrete structures shall be in accordance to this Standardmdash foundation design shall be in accordance DNV-OS-C101 Section 11mdash design of steel structures shall be in accordance to DNV-OS-C101 Sections 4 5 6 and 9mdash possible interface between steel structure and concrete structure shall be included in the design mdash design for load and load effects shall be in accordance with DNV-OS-C101 Section 3 See also special

requirements to concrete structures in this sectionmdash design for accidental limit states shall be in accordance with DNV-OS-C101 Section 7 See also

identifications of hazards in this Standard and Section 6 for reinforced concrete designmdash cathodic protection shall be designed in accordance with DNV-OS-C101 Section 10mdash stability of the structure afloat shall be calculated in accordance with DNV-OSS-102 ldquoRules for

Classification of Floating Production Storage and Loading Unitsrdquo

B 200 Design loads

201 The characteristic values of loads shall be selected according to DNV-OS-C101 Section 3 and this standard

202 The partial safety factors for loads shall be chosen with respect to the limit states and the combination ofloads Values are generally given in DNV-OS-C101 Section 2 Design by LRFD Method and specifically forconcrete in Sec5 D100

B 300 Design resistance

301 The characteristic resistance of a cross-section or a member shall be derived from characteristic valuesof material properties and nominal geometrical dimensions

302 The design resistance is obtained by amending the characteristic values with the use of appropriate partialsafety factors for materials

303 The design resistance shall be determined using this standard

C Load and Load Effects

C 100 General

101 The load and load effects shall be in accordance with DNV-OS-C101 Section 3 The loads are generallyclassified as

a) Environmental E

b) Functional

mdash permanent Gmdash variable Qmdash imposed deformation D mdash accidental A

102 The loads shall include the corresponding external reaction The level of the characteristic loads shall bechosen according to the condition under investigation

mdash under temporary conditions (construction towing and installation)mdash during operationmdash when subject to accidental effectsmdash in a damaged conditionmdash during removal

103 The load effects shall be determined by means of recognized methods that take into account the variationof the load in time and space the configuration and stiffness of the structure relevant environmental and soilconditions and the limit state that shall be verified

104 Simplified methods to compute load effects may be applied if it can be verified that they produce resultson the safe side

105 If dynamic or non-linear effects are of significance as a consequence of a load or a load effect suchdynamic or non-linear effects shall be considered

106 Load effects from hydrodynamic and aerodynamic loads shall be determined by methods which accountsfor the kinematics of the liquid or air the hydrodynamic load and the interaction between liquid structure andsoil For calculation of global load effects from wind simplified models may normally suffice

107 For ground supported structures located in seismic active zones a seismic hazard assessment shall becarried out as detailed in Sec3 A305 Seismic loads shall be specified in terms of a seismic design spectrum ora set of real or artificially simulated earthquake time histories A minimum of four time histories shall be usedto capture the randomness in seismic motions

108 The soil-structure interaction shall be assessed in the determination of the soil reactions used in thecalculation of load effects in the structure Parameters shall be varied with upper and lower bound values toensure that all realistic patterns of distribution are enveloped considering long and short term effectsunevenness of the seabed degrees of elasticity and plasticity in the soil and if relevant in the structure SeeDNV-OS-C101 Section 11

C 200 Environmental loads201 Wind wave tide and current are important sources of environmental loads (E) on many structureslocated offshore See Appendix A for more details In addition depending on location earthquake or ice loadsor both can be significant environmental loads202 ISO 19901-22004 provides detailed recommendation for estimating seismic loads for ELE event Thereturn period for ELE depends on the structure level of exposure and the seismic reserve capacity factor for thestructural system In order to avoid too short return periods the seismic reserve capacity factor is limitedaccording to the structure level of exposure203 Earthquake induced hazards such as liquefaction slope instability faults tsunamis mud volcanoes and shockwaves are out of the scope of this standard Nevertheless they shall be duly considered in the design if applicable204 The computation of ice loads is highly specialized and location dependent and is not covered in detail bythis Standard Ice loads shall be computed by skilled personnel with appropriate knowledge in the physical iceenvironment in the location under consideration and with appropriate experience in developing loads based onthis environment and the load return periods in accordance with DNV-OS-C101 Section 3205 Extreme wave loads

Wave loads from extreme conditions shall be determined by means of an appropriate analysis proceduresupplemented if required by a model test program Global loads on the structure shall be determined Inaddition local loads on various appurtenances attachments and components shall be determined For moredetails see Appendix A206 Diffraction analysisGlobal loads on large volume bodies shall generally be estimated by applying a validated diffraction analysisprocedure In addition local kinematics required in the design of various appurtenances shall be evaluatedincluding incident diffraction and (if appropriate) radiation effects For more details see Appendix A207 Additional requirements for dynamic analysis under wave loads

In cases where the structure can respond dynamically such as in the permanent configuration (fixed orfloating) during wave load or earthquakes or in temporary floating conditions additional parametersassociated with the motions of the structure shall be determined Typically these additional effects shall becaptured in terms of inertia and damping terms in the dynamic analysis Ringing can control the extreme dynamic response of particular types of concrete gravity structure A ringingresponse resembles that generated by an impulse excitation of a linear oscillator it features a rapid build upand slow decay of energy at the resonant period of the structure If it is important ringing is excited by non-linear (second third and higher order) processes in the wave loading that are only a small part of the totalapplied environmental load on a structureThe effects of motions in the permanent configuration such as those occurring in an earthquake floatingstructures or in temporary phases of fixed installations during construction tow or installation on internalfluids such as ballast water in tanks shall be evaluated 208 Model testingThe necessity of model tests to determine extreme wave loads shall be determined on a case-by-case basis SeeAppendix A for more details209 Current loadCurrents through the depth including directionality shall be combined with the design wave conditions Thecharacteristic current load shall be determined in accordance with DNV-OS-C101 Section 3 For more detailssee Appendix AIf found necessary scour protection should be provided around the base of the structure See DNV-OS-C101Section 11210 Wind LoadsWind loads may be determined in accordance with DNV-OS-C101 Sec3 E700

Wind forces on an Offshore Concrete Structure will consist of two parts

a) Wind forces on topside structureb) Wind forces on concrete structure above sea level

For more details see Appendix A

C 300 Functional loads

301 Functional loads are considered to be all loads except environmental loads and include both permanentand variable loads The functional loads are defined in DNV-OS-C101 Sec3 C ldquoPermanent Loadsrdquo and DldquoVariable Functional Loadsrdquo

302 Permanent loads (G) are loads that do not vary in magnitude position or direction during the time periodconsidered These include

mdash self-weight of the structuremdash weight of permanent ballastmdash weight of permanently installed parts of mechanical outfitting including risers etcmdash external hydrostatic pressure up to the mean water levelmdash prestressing force (may also be considered as deformation loads)

303 Variable Functional Loads (Q) originates from normal operations of the structure and varies in positionmagnitude and direction during the period considered They include loads from

mdash personnelmdash modules parts of mechanical outfitting and structural parts planned to be removed during the operation

phasemdash weight of gas and liquid in pipes and process plantsmdash stored goods tanks etcmdash weight and pressure in storage compartments and ballasting systemsmdash temperatures in storages etc (may also be considered as deformation loads)mdash loads occurring during installation and drilling operations etcmdash ordinary boat impact rendering and mooring

304 The assumptions that are made concerning variable loads shall be reflected in a Summary Report andshall be complied with in the operations Possible deviations shall be evaluated and if appropriate shall beconsidered in the assessment of accidental loads

305 Certain loads which can be classified as either permanent or variable may be treated as imposeddeformations (D) Load effects caused by imposed deformations shall be treated in the same way as load effectsfrom other normal loads or by demonstration of strain compatibility and equilibrium between applied loadsdeformations and internal forces

306 Potential imposed deformations are derived from sources that include

mdash thermal effectsmdash prestressing effectsmdash creep and shrinkage effectsmdash differential settlement of foundation components

See also E401

C 400 Accidental loads

401 The Accidental Loads (A) are generally defined in DNV-OS-C101 Sec3 G Accidental Loads

402 Primary sources of accidental loads include

mdash rare occurrences of extreme environmental loadsmdash firesmdash floodingmdash explosionsmdash dropped objectsmdash collisionsmdash unintended pressure difference changes

403 The accidental loads to be considered in the design shall be based on an evaluation of the operationalconditions for the structure due account taken to factors such as personnel qualifications operationalprocedures installations and equipment safety systems and control procedures

404 Rare occurrences of extreme environmental loads

This will include extreme environmental loads such as the extreme seismic action and all other extremeenvironmental loads when relevant ISO 19901-22004 provides detailed recommendation for estimatingseismic loads for ALE event The return period for ALE depends on the structure level of exposure

405 Fires

The principal fire and explosion events are associated with hydrocarbon leakage from flanges valvesequipment seals nozzles ground etc

The following types of fire scenarios (relevant for offshore oilgas production structures) should among othersbe considered

a) Burning blowouts in wellhead areab) Fire related to releases from leaks in risers manifolds loadingunloading or process equipment or storage

tanks including jet fire and fire ball scenariosc) Burning oilgas on sead) Fire in equipment or electrical installationse) Pool fires on deck or seaf) Fire jets

The fire load intensity may be described in terms of thermal flux as a function of time and space or simply astandardized temperature-time curve for different locationsThe fire thermal flux may be calculated on the basis of the type of hydrocarbons release rate combustion timeand location of ignition ventilation and structural geometry using simplified conservative semi-empiricalformulae or analyticalnumerical models of the combustion process406 ExplosionsThe following types of explosions should be considered

mdash ignited gas cloudsmdash explosions in enclosed spaces including machinery spaces and other equipment rooms as well as oilgas

storage tanks

The overpressure load due to expanding combustion products may be described by the pressure variation intime and space It is important to ensure that the rate of rise peak overpressure and area under the curve areadequately represented The spatial correlation over the relevant area that affects the load effect should also beaccounted for Equivalent constant pressure distributions over panels could be established based on moreaccurate methodsThe damage due to explosion should be determined with due account of the dynamic character of the loadeffects Simple conservative single degree of freedom models may be applied When necessary non-linear timedomain analyses based on numerical methods like the finite element method should be appliedFire and explosion events that result from the same scenario of released combustibles and ignition should beassumed to occur at the same time ie to be fully dependent The fire and blast analyses should be performedby taking into account the effects of one on the otherThe damage done to the fire protection by an explosion preceding the fire should be considered407 CollisionsThe impact loads are characterised by kinetic energy impact geometry and the relationship between load andindentation Impact loads may be caused by

mdash vessels in service to and from the installation including supply vesselsmdash tankers loading at the fieldmdash ships and fishing vessels passing the installationmdash floating installations such as flotelsmdash aircraft on service to and from the fieldmdash dropped or sliding objectsmdash fishing gearmdash icebergs or ice

The collision energy can be determined on the basis of relevant masses velocities and directions of ships oraircraft that may collide with installation When considering the installation all traffic in the relevant areashould be mapped and possible future changes in vessel operational pattern should be accounted for Designvalues for collisions are determined based on an overall evaluation of possible events The velocity can bedetermined based on the assumption of a drifting ship or on the assumption of uncontrolled operation of theshipIn the early phases of platform design the mass of supply ships should normally not be selected less than 5000tons and the speed not less than 05 ms and 2 ms for ULS and ALS design checks respectively Ahydrodynamic (added) mass of 40 for sideways and 10 for bow and stern impact can be assumedThe most probable impact locations and impact geometry should be established based on the dimensions andgeometry of the structure and vessel and should account for tidal changes operational sea-state and motions ofthe vessel and structure which has free modes of behaviour Unless more detailed investigations are done forthe relevant vessel and platform the impact zone for supply vessel on a fixed offshore structure should beconsidered to be between 10 m below LAT and 13 m above HAT

408 Dropped objects

Loads due to dropped objects should for instance include the following types of incidents

mdash dropped cargo from lifting gearmdash failing lifting gearmdash unintentionally swinging objectsmdash loss of valves designed to prevent blow-out or loss of other drilling equipment

The impact energy from the lifting gear can be determined based on lifting capacity and lifting height and onthe expected weight distribution in the objects being lifted

Unless more accurate calculations are carried out the load from dropped objects may be based on the safeworking load for the lifting equipment This load should be assumed to be failing from lifting gear from highestspecified height and at the most unfavourable place Sideways movements of the dropped object due to possiblemotion of the structure and the crane hook should be considered

The trajectory and velocity of a falling object will be affected by entering into water The trajectories andvelocity of objects dropped in water should be determined on the basis of the initial velocity impact angle withwater effect of water impact possible current velocity and the hydrodynamic resistance It is considered non-conservative for impacts in shallow water depths to neglect the above effects

The impact effect of long objects such as pipes should be subject to special consideration

409 Unintended pressure difference changes

Changes in intended pressure differences or buoyancy caused for instance by defects in or wrong use ofseparation walls valves pumps or pipes connecting separate compartments as well as safety equipment tocontrol or monitor pressure shall be considered

Unintended distribution of ballast due to operational or technical faults should also be considered

410 Floating structure in damaged condition

Floating structures which experience buoyancy loss will have an abnormal floating position Thecorresponding abnormal variable and environmental loads should be considered

Adequate global structural strength should be documented for abnormal floating conditions considered in thedamage stability check as well as tightness or ability to handle potential leakages in the tilted condition

411 Combination of accidental loads

When accidental loads occur simultaneously the probability level (10-4) applies to the combination of theseloads Unless the accidental loads are caused by the same phenomenon (like hydrocarbon gas fires andexplosions) the occurrence of different accidental loads can be assumed to be statistically independentHowever due attention shall be taken to the result of any quantitative risk assessment

Guidance note

While in principle the combination of two different accidental loads with exceedance probability of 10-2 or one at 10-3

and the other at a 10-1 level correspond to a 10-4 event individual accidental loads at a probability level of 10-4commonly will be most critical

D Load Combinations and Partial Safety Factors

D 100 Partial load factors γf

101 The load factors are specified in DNV-OS-C101 Sec2 D ldquoDesign by LRFD Methodrdquo and in Table D1and Table D2

102 The load factors shall be calibrated if an alternative national standard is used as a reference standard forthe detailed design of the concrete structure in order to provide an equivalent level of safety The equivalentsafety shall be documented Requirements to special evaluations are given in Appendix D

103 When checking the serviceability limit state SLS the partial load factor γf shall be 10 for all loads

104 When checking the fatigue failure limit state FLS the partial load factor γf shall be 10 for all loads

105 In the ALS the partial load factor shall be 10 for all loads

106 For structures with steel reinforcement the ultimate limit state ULS shall be checked for two loadcombinations (a) and (b) with load factors according to Table D1 (Table D1 of DNV-OS-C101 Section 2)

107 For structures with FRP reinforcement the ultimate limit state ULS shall be checked for loadcombinations according to Table D2 It shall be noted that design of structures reinforced by FRP three newload combinations c d and e are identified in addition to the load combinations in Table D1

108 The loads shall be combined in the most unfavourable way provided that the combination is physicallypossible and permitted according to the load specifications Loading conditions that are physically possible butnot intended or permitted to occur in expected operations shall be included by assessing probability ofoccurrence and accounted for as either accidental conditions in the accidental damage limit state (ALS) or aspart of the ordinary design conditions included in the ULS Such conditions may be omitted in cases where theannual probability of occurrence can be assumed to be less than 10-4

109 For permanent loads a load factor of 10 in load combination a) shall be used where this gives a moreunfavourable load effect For external hydrostatic pressure and internal pressures from a free surface a loadfactor of 12 may normally be used provided that the load effect can be determined with normal accuracyWhere second order effects are important a load factor of 13 shall be used

110 A load factor of 10 shall be applied to the weight of soil included in the geotechnical calculations

111 Prestressing loads may be considered as imposed deformations Due account shall be taken of the timedependent effects in calculation of effective characteristic forces

112 The definition of limit state categories is valid for the foundation design with the exception that failuredue to cyclic loading is treated as an ULS alternatively as an ALS using load and material coefficients asdefined for these limit state categories

113 Where a load is a result of high counteracting and independent hydrostatic pressures the pressuredifference shall be multiplied by the load factor The pressure difference shall be taken as no less than thesmaller of either one tenth of the highest pressure or 100 kPa This does not apply when the pressure is balancedby direct flow communication The possibility of communication channel being blocked shall then be part ofthe risk assessment

Table D1 Recommended partial factors γf for loads for the ultimate limit state (ULS) Load combinations (from DNV-OS-C101) for structures with steel reinforcementCombination of

design loadsLoad categories

G Q E D Pa) 13 13 07a 10 0911b

b) 10 10 13a 10 0911 b Load categories are

D = deformation loadE = environmental loadG = permanent loadP = prestressing loadQ = variable functional loada Factor may have to be amended for areas with other long term distribution functions than North Sea conditionsb The more conservative value of 09 and 11 shall be used as a load factor in the designFor description of load categories see DNV-OS-C101 Section 2 and D108 through D113 below

Table D2 Recommended partial factors γf for loads for the ultimate limit state (ULS) load combinations for structures with FRP reinforcement

Combination of design loads

Load categoriesG Q1 Q2 E D P

a 13 13 13 07a 10 0912b

b 10 10 10 13a 10 0912b

c 13 13 13 0912b

d 13 13 10 0912b

e 10 13 10 0912b

Load categories are

G = Permanent load E = Environmental load (Load factors for environmental load E may have to be amended for areas with other long term

distribution functions than North Sea conditions) D = deformation load (settlement temperature etc)P = Prestressing loadQ1 = Variable functional load of permanent character are live loads that the structure may be exposed to for its entire service life

or a considerable part of it eg load from prestressing dead weight of the structure weight of furniture stored goods etcQ2 = Variable functional load of variable nature are live loads that the structure can be exposed to only for limited durations much

less than the service life such as eg weight of occupants and (not permanently stored) vehiclesa Factor may have to be amended for areas with other long term distribution functions than North Sea conditionsb The more conservative value of 09 and 12 shall be used as a load factor in the design

D 200 Combinations of loads201 Table B2 of DNV-OS-C101 Sec3 B gives a more detailed description of how loads shall be combinedWhen environmental and accidental loads are acting together the given probabilities apply to the combinationof these loads202 For temporary phases if a progressive collapse in the installation does not entail the risk of loss of humanlife injury or damage to people or the environment or significant financial losses a shorter return period thanthat given in DNV-OS-C101 Sec3 Table B2 for environmental loads may be considered203 The return conditions to be considered should be related to the duration of the operation As a generalguidance the criteria given in Table D3 may be applied

D 300 Consequence of failure301 Structures can be categorised by various levels of exposure to determine criteria that are appropriate forthe intended service of the structure The levels are determined by consideration of life safety and consequencesof failure302 Life safety considers the manning situation in respect of personnel on the facility when the failure eventwould occur303 Consequences of failure consider the potential risk to life of personnel brought in to react to any incidentthe potential risk of environmental damage and the potential risk of economic losses

E Structural Analysis

E 100 General101 Structural analysis is the process of determining the load effects within a structure or part thereof inresponse to each significant set of loads This clause specifies requirements for the various forms of structuralanalysis necessary to define the response of the structure during each stage of its life Load effects calculatedby structural analysis shall be used as part of the design102 Complex or unusual structural types can require forms of analysis which are not described within thisStandard These shall be performed in accordance with the principle of providing sufficient analyses toaccurately assess all significant load effects within the structure103 In order to ensure successful structural analysis of an Offshore Concrete Structure it is required that

mdash All necessary analyses are performed on the basis of an accurate and consistent definition of the structureand assessment of loads thereon

mdash These analyses are performed using appropriate methods have accurate boundary conditions and are ofsuitable type

mdash Suitable verified results are available in due time for use in design or reassessment

104 Interfaces between structural designers topsides designer hydrodynamic analysts geotechnicalengineers and other relevant parties shall be set up The schedule of supply of data regarding loads (includingreactive actions) shall be determined and monitored Such an interface shall ensure that this data is in the correctformat covers all necessary locations and is provided for all required limit states and for all significant stagesin the lifetime of the structure105 The number and extent of analyses to be performed shall cover all components of the structure throughall stages of its life ie construction installation in-service conditions and removalretrievalrelocationHowever if it can be clearly demonstrated and documented that particular stages in the life of a component willnot govern its design such stages need not be analysed explicitly for all components106 Sufficient structural analyses shall be performed to provide load effects suitable for use when checkingall components of the primary structure for the required design conditions and limit states At least one suchanalysis should normally represent global behaviour of the structure for each significant stage of its life107 Secondary components of the structure shall be assessed by analysis if necessary to determine theirintegrity and durability and to quantify the distribution of load effects on the primary structure Such analysesmay be performed in isolation of the primary structure analysis but shall include deformations of thesupporting primary structure where significant

Table D3 Environmental criteriaDuration of use Environmental criteria

Up to 3 days Specific weather window3 days to 1 week More than 1 year seasonal

1 week to 1 month 10 years return seasonal1 month to 1 year 100 years return seasonalMore than 1 year 100 years return all year

108 When present the stiffness of the topsides and other primary structures shall be simulated in globalanalyses in sufficient detail to adequately represent the interface with the concrete substructure such that allloads from the topsides are appropriately distributed to the concrete substructure The relative stiffness oftopsides and concrete substructure shall be accurately simulated where this has a significant effect on globalload paths and load effects Particular attention shall be paid to relative stiffness when assessing dynamicresponse

109 Where appropriate the analysis shall include a representation of its foundation simulated by stiffnesselements or by reactive loads

110 All structural analyses required for design of the structure shall be carried out in accordance with theplanned analysis schedule using the most recent geometric material boundary condition load and other data

111 The structure shall be analysed for significant loads during each stage of its life Where simultaneousloading is possible these loads shall be applied combined in such a way as to maximize load effects at eachlocation to be checked The loads that contribute to these combinations shall include appropriate load factorsfor each limit state being checked

112 Where assumptions are made to simplify the analysis and enable a particular calculation method theseshall be clearly recorded in the documentation or calculations The effects of such assumptions on load effectsshall be quantified and incorporated as necessary

113 Analysis of the global structure or local components is normally performed by the finite element methodComputer software used to perform finite element analysis shall comply with a recognized international qualitystandard such as ISO 9000-3 or shall be verified for its intended use prior to the start of the analysis Elementtypes load applications meshing limits and analysis types to be used in the structural analysis shall all beincluded in the verification

114 Where finite element analysis is performed consideration shall be given to the inaccuracy inherent in theelement formulation particularly where lower order elements or coarse element meshes are used Verificationand ldquobenchmarkrdquo testing of the software shall be used to identify element limitations and the computermodelling shall be arranged to provide reliable results

115 Hand calculations are generally limited to simple components of the structure (beams regular panelssecondary structures etc) under simplified loads (ie uniform pressure point or distributed loads) Themethodology used shall reflect standard engineering practice with due consideration for the conditions ofequilibrium and compatibility Elastic or plastic design principles may be adopted dependent on the limit statebeing checked and the requirements for the analysis being performed

116 Computer spread-sheets are electronic methods of performing hand calculations and shall be subject tothe same requirements Where such spread-sheets do not produce output showing the methodology andequations used adequate supporting calculations shall be provided to verify the results of comprehensive testproblems Sufficient checks shall be provided to verify all elements in the spread-sheet that will be used for thecomponent being assessed

117 Special forms of analysis for concrete structures such as the strut and tie approach may also be usedbut must conform to up to date accepted theories and shall adhere to the general principles of civilstructuralengineering Unless the method is well known and understood throughout the industry references to sourcematerial for the method being used shall be provided in the documentation or calculations

118 Non-linear finite element analysis may be used to demonstrate ultimate capacity of the structure or thecapacity of complicated 2-D and 3-D (discontinuity) regions Software used for this purpose shall be subject tothe same verification requirements as above Verification of non-linear analysis software used in this way shallinclude at least one comparison against experimental results or a reliable worked example of a similar detail

119 Structural analyses shall be thoroughly verified to provide confidence in the results obtainedVerification is required to check that input to the calculations is correct and to ensure that sensible results havebeen obtained

120 Input data for a particular structural analysis shall be subject to at least the following checks

mdash that the model adequately represents the geometry of the intended structure or componentmdash that the specified material properties have been usedmdash that sufficient and correct loads have been appliedmdash that suitable and justifiable boundary conditions have been simulatedmdash that an appropriate analysis type and methodology have been used for the analysis

121 Verification of the results of an analysis will in general vary depending on the nature of that analysisTypical output quantities that shall be checked as appropriate include the following

mdash individual and summed reactions to ensure that these balance the applied loadsmdash deformations of the structure to verify that these are sensible and that they demonstrate compatibility

between componentsmdash natural periods and mode shapes if appropriate

mdash load paths bending moment diagrams stress levels etc to check that these satisfy equilibriumrequirements

122 Successful execution of an analysis shall be recorded and pertinent parties informed of results andconclusions so that implications for the design process are formally recognized

123 Each structural analysis shall be thoroughly documented to record its extent applicability input dataverification and results obtained The following information shall be produced as a minimum to document eachanalysis

mdash Purpose and scope of the analysis and the limits of its applicabilitymdash References to methods used and the justification of any assumptions mademdash The assumed geometry showing and justifying any deviations from the current structural geometrymdash Material properties used in the analysismdash Boundary conditions applied to the structure or componentmdash Summed magnitude and direction of all loadsmdash Pertinent results from the analysis and crosschecks to verify the accuracy of the simulationmdash Clear presentation of those results of the analysis that is required for further analysis structural design or

reassessment

124 Results of the analysis will normally take the form of load effects for which the structure shall bedesigned to withstand Typical load effects required for the design of fixed Offshore Concrete Structuresinclude the following

mdash Displacements and vibrations which shall be within acceptable limits for operation of the platformmdash Section forces from which the capacity of concrete sections and necessary reinforcement requirements can

be determinedmdash Section strains used to determine crack widths and assess water tightness stress occurrences used to check

the fatigue life of the structure

E 200 Youngrsquos modulus to be used in load effect analyses

Concrete

201 In the calculation of strains and section forces the relation between Youngrsquos modulus of concrete Ec andcompressive cylinder strength fcck may be taken as

Ecn = 22 000 (fcck10)03

if the factor is not determined by testing

202 Ecn may be determined as the secant modulus (see Section 4) by testing E-modulus in accordance withappropriate International Standard The strength fcck is determined with the same cylinder samples Ecn shallbe determined as the mean value of the test results from at least 5 concrete test mixes with the same aggregatesand strength which will be used in the prospective concrete

203 To consider loading of early age concrete the characteristic cylinder strength at the actual time of loadingmay be used

204 The effect of cracking shall be considered in cases where structural displacements cause increased forcesand moments see E1200

205 If the Youngrsquos modulus of lightweight aggregate concrete is not determined by testing the Youngrsquosmodulus shall be reduced by multiplying the value obtained according to E201 by a factor (ρ ρ1)15 whereρ1 = 2200 kgm3

206 For impact type of loading or rapid oscillations the moduli of elasticity calculated according to E201 andE202 can be increased by up to 15 dependent on strain rate

207 The Youngrsquos modulus predicted in E201 may be used for a temperature range from -50degC to 100degC Forshort-term temperatures (fire) that range from 100degC to 200degC the Youngrsquos modulus can be taken as 90 percent of Eck given in E201 For temperatures above 200degC the concrete strain properties including creep andthermal strain shall be determined specially

Steel reinforcement

208 The characteristic Youngrsquos modulus of non-prestressed reinforcement may be taken as

Esk = 200 000 MPa

209 At high temperatures of short duration (fire) the Youngrsquos modulus of steel may be taken according toE208 for temperatures up to 200degC as long as more precise values are not known For temperatures above200degC the strain properties of steel shall be determined separately

210 For prestressed reinforcement the force-strain relationship shall be known for the steel type and make inquestion

FRP reinforcement211 The characteristic value of stiffness for FRP reinforcement can be estimated by the sample mean ofstiffness data from tests on a representative sample of specimens It shall be reported in the Material Certificatefor relevant temperatures212 At high temperatures of short duration (fire) the Youngrsquos modulus of FRP shall be documented

E 300 Effects of temperature shrinkage creep and relaxation301 An accurate calculation of deformation loads caused by temperature effects can only be obtained from anon-linear analysis reflecting realistic material properties of reinforced concrete

Concrete302 The linear coefficient of thermal expansion (α) for both normal weight concrete and reinforcement shallbe taken as 10-5 per degC when calculating the effects of thermal loads unless there is adequate basis for selectingother values The linear coefficient of thermal expansion for light weight aggregate concrete shall be determined for theactual concrete mix designWhere the temperature induced loads are significant testing is normally to be carried out to determine (α)For concrete exposed to low temperatures the temperature expansion coefficient (α) shall be determined byrelevant tests of the material303 Values of concrete creep and shrinkage shall be chosen on the basis of the conditions surroundings of thestructure (temperature relative humidity etc) sectional dimensions concrete mixture and age304 The creep strain is assumed to be proportional to the concrete stress when load effects are calculated Atconstant concrete stress the creep strain is

whereϕ is the creep coefficientσc is the concrete stress due to long-term loading

305 For all loads the creep strain shall be calculated in proportion to the duration of the load306 If creep is considered in the calculation of forces due to shrinkage it can be assumed that both creep andshrinkage have the same time dependent development307 For lightweight aggregate concrete the creep coefficient ϕ can be assumed equal to the value of normalweight concrete multiplied by a factor (ρ ρ1)15 for ρ gt 1800 kgm3 For lightweight concrete with ρ lt 1500kgm3 a factor 12 (ρ ρ1)15 can be used For intermediate values of ρ linear interpolation may be appliedwhere ρ1 = 2200 kgm3

308 The effect of relaxation in prestressed reinforcement shall be calculated in proportion to the time periodover which the relaxation occurs If there are no exhaustive test results available for the steel type and make inquestion the values given in Figure 1 can be used Normally testing is expected to be based on at least 10 000hours loading

Figure 1 Long-term relaxation in prestressing steel

ck

cccc E

ϕσϕεε ==

2

4

6

8

10

12

14

16

18

45 50 55 60 65 70 75 80

Rel

axat

ion

in

per

cen

t o

f re

lax

atio

n s

tres

s

R elax ation stress in per cen t o f tensile strength

Paten ted co ld draw n tem pered steelA s-ro lled steelPaten ted co ld draw n u ntem pered steel

309 If the steel experiences a temperature T higher than T = 20degC for a long period of time a quantityk1(T-T1) shall be added to the relaxation in percentage of relaxation stress found in the figure where the factork1 for

mdash cold drawn untempered steel is 015 per degCmdash cold drawn tempered steel is 010 per degC

These values shall not be used if the steel temperatures exceed 80degC for long periods of time310 The effect of relaxation in prestressed FRP reinforcement shall be calculated in proportion to the timeperiod over which the relaxation occurs It shall be reported in the Material Certificate for relevanttemperatures

E 400 Special load effectsDeformation Loads401 Deformation induced loads created by imposed deformations in the structure are loads to be treated aseither deformation loads (D) or as Functional Loads see C300Examples of such loads may be

mdash differential settlementmdash temperature effectsmdash shrinkagemdash loads in flexible members connected to stiff members may in some cases be seen as deformation induced

loadsmdash changes in strain due to absorption

In case of a ductile mode of failure and where second order effects are negligible the effect of deformationloads may normally be neglectedA typical example of a ductile mode of failure is a flexural failure in which sufficient rotational capacity existsVerification of sufficient rotational capacity may in most cases be based on simplified considerations402 Imposed deformations normally have a significant influence on the shear resistance of a section andshall be duly considered in the designThe characteristic value of deformation imposed loads is normally evaluated on the basis of defined maximumand minimum values for the parameters governing its magnitudeIn practice effects due to imposed deformations may be calculated using a linear elastic model and a constantYoungrsquos modulus throughout the structure Possible stiffness reductions may be estimated separately byreducing the flexural and axial stiffness to account for cracking of the concrete Special considerations anddocumentation of the stiffness shall be required403 Creep effects shall be considered where relevant An accurate calculated assessment of creep in shellstructures can only be obtained by computer calculations using non-linear finite element programs Sec6 C700outlines procedures to roughly estimate the effects of creep

Effect of Water Pressure404 The effect of water pressure in the concrete shall be fully considered when relevant405 The effect of hydrostatic forces acting on the faces of cracks shall be taken into account in the analyticalmodels used for prediction of concrete cross sectional strength This effect is also to be taken into account whenactual load effects are evaluatedEffects of water pressure in cracks may be neglected for structural elements exposed to less than 100 m ofwaterhead

Loss of Intended Underpressure406 For structures designed with an intended underpressure relative to external pressure a design conditionwhere the intended underpressure is lost shall be evaluatedThis load effect may be categorized as an accidental load effect Load combinations and load and materialfactors are then to be taken according to ALS criteriaMore stringent criteria may be specified by the Client for this situation (eg increased material factor loadfactors etc) due to eg costly and excessive repair or if the structure is storing oil (risk of oil spillage)

Weight of Concrete grout LWA concrete407 The long-term effect of water absorption shall be considered in the estimation of concrete weights inparticular for floating structures This also applies for concrete and grout with and without fibres

E 500 Physical representation501 Dimensions used in structural analysis calculations shall represent the structure as accurately as

necessary to produce reliable estimates of load effects Changes in significant dimensions as a result of designchanges shall be monitored both during and after the completion of an analysis Where this impacts on theaccuracy of the analysis the changes shall be incorporated by reanalysis of the structure under investigationFor more details see Appendix B

E 600 Loads

601 Loads shall be determined by recognized methods taking into account the variation of loads in time andspace Such loads shall be included in the structural analysis in a realistic manner representing the magnitudedirection and time variation of such loads For more details see Appendix B

E 700 Mass simulation

701 A suitable representation of the mass of the structure shall be required for the purposes of dynamicanalysis motion prediction and mass-acceleration loads while floating For more details see Appendix B

E 800 Damping

801 Damping arises from a number of sources including structural damping material damping radiationdamping hydrodynamic damping and frictional damping between moving parts Its magnitude is dependent onthe type of analysis being performed In the absence of substantiating values obtained from existing platformmeasurements or other reliable sources a value not greater than 3 of critical damping may be used

E 900 Linear elastic static analysis

901 It is generally acceptable for the behaviour of a structure or component to be based on linear elastic staticanalysis unless there is a likelihood of significant dynamic or non-linear response to a given type of loadingIn such cases dynamic or non-linear analysis approaches shall be required For further details with respect tostructural analyses see Appendix C

E 1000 Dynamic analysis

1001 Fixed structures with natural periods of the global structure greater than 25s can be susceptible todynamic response due to wave load during in-service conditions at least for fatigue assessment Structures inshallow water or subject to extreme wave conditions may exhibit significant dynamic response at lower periodsdue to the higher frequency content of shallow water or particularly steep waves For further details withrespect to dynamic analyses see Appendix C

E 1100 Pseudo-static analysis

1101 In this context pseudo-static analysis refers to any analysis where dynamic loads are representedapproximately by a factor on static loads or by equivalent quasi-static loads The former approach is appropriatewhere static and dynamic load effects give an essentially similar response pattern within the structure butdiffers in magnitude For further details see Appendix C

E 1200 Non-linear analysis

1201 Non-linear behaviour shall be considered in structural analysis when determining load effects in thefollowing cases

mdash Where significant regions of cracking occur in a structure such that global load paths are affectedmdash Where such cracking regions affect the magnitude of loads (temperature loads uneven seabed effects

dynamic response etc)mdash Where the component depends upon significant non-linear material behaviour to resist a given set of loads

such as in response to accidents or abnormal level earthquakemdash For slender members in compression where deflection effects are significant

For further details see Appendix C

E 1300 Probabilistic analysis

1301 It is generally acceptable to base in-service structural analysis of an Offshore Concrete Structuresubjected to wave load on the principles of deterministic analysis predicting response to specific eventsHowever where stochastic or probabilistic methods are shown to be more appropriate for a particular limit state(ie fatigue) these shall be substituted as needed Spectral fatigue analysis is normally required wherestructural dynamics are significant

1302 Such methods typically linearize load effects This can restrict their use where non-linear response ofthe structure or component is significant If non-deterministic analysis methods are still to be used time domainresponse to transient loading might be necessary

1303 Where spectral analysis methods are used for calculating response to random wave load sufficientwave conditions shall be analysed to ensure that dynamic response close to structural natural periods and peakwave energy is accurately assessed

E 1400 Reliability analysis

1401 Reliability assessment of structures is permitted under these rules to assess the risk of failure of astructure and ensure that this falls below acceptable levels Such analysis shall be performed in accordance withacceptable current practice

E 1500 Analyses requirements

1501 All structural analyses performed shall simulate with sufficient accuracy the response of the structureor component for the limit state being considered This may be achieved by appropriate selection of the analysistype with due regard to the nature of loads applied and the expected response of the structure

1502 Table E1 gives general guidance as to the type of analysis that shall be adopted for each designcondition for the structure Further details are provided from E1600 to E2300

E 1600 Analysis of construction stages

1601 Sufficient analyses shall be performed on components of the structure during construction to ensuretheir integrity at all significant stages of the construction and assembly process and to assess built-in stressesfrom restrained deformations Construction stages shall include onshore and inshore operations

1602 Consideration shall be given to the sequence of construction in determining load effects and to the ageof the concrete in determining resistance Specific consideration shall be given to the stability of componentsunder construction Adequate loads for temporary support such as crane footings shall be included in theanalysis

1603 Assessment of the structure during construction stages may normally be performed using staticanalysis However dynamic response to wind turbulence might need to be calculated for tall slender structuresand consideration shall be given to other possible dynamic load effects such as earthquakes occurring duringthe construction phase

Long term stress redistribution shall be considered for the complete structure considering creep effects on thebuilt stresses accumulated during construction

E 1700 Transportation analysis

1701 Analysis of a fixed concrete structure shall include the assessment of structural integrity duringsignificant stages of the sea tow of the structure whether it is self-floating barge supported or barge assistedThe representation of the structure during such operations shall be consistent with the stage being representedincorporating the correct amount of ballast and simulating only those components of the topsides actuallyinstalled

1702 Analysis during sea tow should normally be based on linear static analysis representing the motion ofthe concrete structure by peak heave sway surge pitch and roll accelerations as predicted by hydrodynamicanalysis For such analysis to be valid it shall be demonstrated that motions in the natural periods of majorcomponents of the structure such as the shafts will not be significantly excitated by this global motion Ifdynamic effects are deemed important they shall be incorporated in accordance with E1000 The analysis ofthe tow shall be in accordance with the DNV Rules for Planning and Execution of Marine Operations

1703 Fatigue damage can result from extreme tow duration in heavy seas If this is significant fatiguedamage accrued shall be accumulated together with that calculated for in-service conditions in accordance withE2000

1704 Consideration shall be given to possible damage scenarios during sea tow Sufficient structural analysesshould be performed to ensure adequate integrity of the structure preventing complete loss in the event of

Table E1 Appropriate Types of AnalysisCondition Appropriate types of analysis

Construction Linear static analysis is generally appropriateTowing to location

Linear static analysis is generally appropriate Dynamic effects may be significant in response to hydrodynamic motions These can normally be simulated by pseudo-static analysis

Installation Linear static analysis is generally appropriateIn-service strength and Serviceability

Linear static or pseudo-static analysis is generally appropriate for global load path analysis

Fatigue Linear analysis is generally appropriate Dynamic effects may be significant for short period waves A pseudo-static deterministic approach is normally acceptable

Seismic Dynamic analysis is normally required where seismic ground motion is significant Non-linear analysis might need to be considered for abnormal level earthquakes

Accidental Non-linear analysis is normally required for significant accidental loads Dynamic response can be significant

Removalreuse As per transportation and installation

collision with tugs or other vessels present during the transportation stage In particular progressive collapsedue to successive flooding of compartments shall be prevented

E 1800 Installation and deck mating analysis

1801 Structural analysis shall be performed at critical stages of the deck mating and installation stages Suchanalyses shall as a minimum cover times of maximum pressure differential across various components ofconcrete structure Once again the configuration of the structure at each stage of the setting down operationshould reflect the planned condition and inclination of the structure and the associated distribution of ballast

1802 Deck mating ballasting down and planned setting down on the sea floor shall normally be analysed bya linear static approach As these phases normally represent the largest external water heads implosion orbuckling should be analysed The effect of unevenness in the seabed shall be considered in assessing seabedreactions in an un-grouted state

E 1900 In-service strength and serviceability analyses

1901 At least one global analysis of the structure shall be performed in its in-service configuration suitablefor subsequent strength and serviceability assessment The structure shall also be analysed for extreme waveeffects using ALS load factors unless it can be conclusively demonstrated that this limit state is always lessonerous than the corresponding ULS condition

1902 Local analysis shall be performed to assess secondary structure and details that appear from the globalanalysis to be heavily loaded or that are complex in form or loading Such analyses may be based on non-linearmethods if these are more appropriate to the component behaviour

1903 It is generally acceptable to base all strength analysis of an in-service concrete platform on deterministicanalysis predicting response to specific extreme waves Sufficient wave periods directions and wave phasesshall be considered to obtain maximum response in each type of component checked Consideration shall begiven to waves of lower than the maximum height if greater response can be obtained due to larger dynamiceffects at smaller wave periods

E 2000 Fatigue analysis

2001 When required detailed fatigue analysis shall be based on a cumulative damage assessment performedover the proposed lifetime of the structure The analysis shall include transportation stages if significant andshould consider the effects of the range of sea states and directions to which the structure will be subjected

2002 A linear representation of the overall structure is generally acceptable for the evaluation of global loadpaths for fatigue analysis The structural analysis shall include the effects of permanent live hydrostatic anddeformational loads It shall be justifiable to use reduced topside and other loads in the fatigue analysis on thebasis that typical rather than extreme loads through its life are required Significant changes in static loadthrough the lifetime of the structure shall be analysed separately and fatigue damage shall be accumulated overeach phase

2003 Dynamic amplification is likely to be more significant for the relatively short wave periods causing themajority of fatigue damage Fatigue analysis shall therefore consider the effects of dynamic excitation inappropriate detail either by pseudo-static or by dynamic response analysis Deterministic or stochastic typesof analysis are both permissible subject to the following provisions

2004 For deterministic analysis the selected individual waves to which the structure is subjected shall bebased on a representative spread of wave heights and periods For structures that are dynamically sensitivethese shall include several wave periods at or near each natural period of the structure to ensure that dynamiceffects are accurately assessed Consideration shall also be given to the higher frequency content in largerwaves that may cause dynamic excitation

2005 Sufficient wave cases shall be analysed for probabilistic analysis to adequately represent the stresstransfer functions of the structure Non-linear response of the structure shall be incorporated into the analysisusing appropriate methods if significant

E 2100 Seismic analysis

2101 ISO 19901-2 provides recommendations for the seismic analysis of Offshore Concrete Structures forboth ELE and ALE earthquakes

E 2200 Accidental and overload analyses

2201 Analysis of the structure under accidental conditions such as ship collision helicopter impact oriceberg collision shall consider the following

mdash local behaviour of the impacted areamdash global strength of the structure against overall collapsemdash post-damage integrity of the structure

2202 The resistance of the impact area may be studied using local models The contact area and perimetershall be evaluated based on predicted non-linear behaviour of the structure and of the impacting object Non-linear analyses may be required since the structure will generally deform substantially under the accidentalloads Appropriate boundary conditions shall be provided far enough away from the damaged region forinaccuracies to be minimized

2203 Global analysis of the structure under accidental loads may be required to ensure that a progressivecollapse is not initiated The analysis should include the weakening effect of damage to the structure in theimpacted area When large deformations of the structure is likely for the impact loads a global non-linearanalysis may be required to simulate the redistribution of load effects caused by the large deformations Theglobal analysis may be based on a simple representation of the structure sufficient to simulate progressivecollapse Deflection effects shall be included if significant

2204 Energy absorption of the structure will arise from the combined effect of local and global deformationSufficient deformation of the structure to absorb the impact energy from the collision not absorbed by theimpacting object shall be documented

2205 Analysis of the structure in its damaged condition may normally be performed using linear staticanalysis Damaged components of the structure shall be removed from this analysis or appropriately weakenedto simulate their reduced strength and stiffness

E 2300 Platform removalreuse

2301 Analysis of the structure for removal shall accurately represent the structure during this phase Theanalysis shall have sufficient accuracy to simulate pressure differential effects that are significant during thisstage The analysis shall include suction forces that shall be overcome prior to separation from the sea floor ifappropriate Suitable sensitivity to the suction coefficient shall be incorporated The possibility of unevenseparation from the seabed and drop-off of soil or underbase grout shortly after separation shall be consideredand structural response to subsequent motions shall be evaluated

2302 Weights of accumulated debris and marine growth shall also be considered if these are not to beremoved Items to be removed from the structure such as the topsides conductors and risers shall be omittedfrom the analysis

2303 The condition of the concrete and reinforcement should account for degradation of the materials duringthe life of the platform If the analysis is carried out immediately prior to removal then material degradationshall take account of the results from recent underwater surveys and inspections

F Topside Interface Design

F 100 Introduction

101 The design of the interface between a steel topsides structure and a concrete substructure requires carefulconsideration by both the topsides and substructure designers

102 Particular attention shall be paid to ensure that all relevant information is exchanged between the topsidesand substructure design teams

103 If topside and substructure construction are separate contracts special care shall be taken to handle theinterface responsibility It shall be clear who is responsible for input to and from the topside engineeringcontractor as part of a technical coordination procedure

F 200 Basis for design

201 As part of establishing and maintaining adequate handling of topsidesubstructure interface throughoutthe design process all necessary design information shall be defined Plans must be prepared in order to securetimely supply of data The interface shall define format of data ensure consistency with respect to locationsand elevations and that data is provided for all required limit states and significant stages in the lifetime of thestructure such as

mdash installationmating of topsidemdash the platform transportation and installationmdash the platform operating phasemdash decommissioning

202 Important aspects related to these phases are time-dependent deformations such as creep effect ofvarying water pressure at different drafts varying ground-pressure distribution under the base accelerationsand possible inclination during tow as well as resulting from accidental flooding Varying shaft inclination intemporary phases prior to installationmating of the topside might cause built-in stresses to be dealt with in thedesign of topside substructure and the deck-shaft connection It is of vital importance that the designassumptions are consistent

203 The structural analysis of the concrete substructure may consider the topside in varying detail andsophistication depending on its effect on the design of different structural parts Typically the design of upperparts of the substructure (shaft) is based on FE-analysis comprising also the topside stiffness matrix It isrequired that the stiffness of the topside and the load effects imposed by the topside is represented in sufficientdetail to ensure adequate distribution between topside and substructure as well as within the substructure

204 The documentation to be provided as basis for proper interface design shall also cover

mdash shaft configurationmdash top of shaft layoutmdash deck elevationmdash loads to be applied on top of concrete structure from topside (ie topside weights for design purposes incl

CoG etc)mdash tolerances (ie for concrete geometry tie bolts tendons bearing tubes embedment plates etc)mdash deck mating tolerances to allow for deformations during load transfer

F 300 Deckshaft structural connection

301 Several alternatives are viable for the structural connection between the topside and the substructure Thedetailing must consider initial contact and ensure load distribution as presumed in structural analysis anddesign

302 The physical interface is very often present between a steel module support frame and the OffshoreConcrete Structure Typically temporary tubular bearings (steel pipes) resting on embedded steel plates areused for transferring the deck weight on top of Offshore Concrete Structure shafts The area between the tubularbearings is typically grouted before activation of prestressed anchor bolts

303 The design of intersection between the module support frame grout and top of shaft(s) shall take dueaccount of shear forces (friction check) arising from tilt in temporary phases or platform accelerations in theoperational phase Compression check is required for the grout Eventual uplift shall also be accounted for

304 If non-rigid topside to substructure connection is selected such as an array of elastomeric bearingsconsideration should be given to the expansion and contraction of oil risers heated by hot products and theinteraction between rigid pipes and a flexible structural connection

305 Depending on the connection selected the detailing and layout must allow for necessary inspection andmaintenance Special consideration should be given to gaining access to fatigue prone details and if access isnot possible a suitably large design fatigue life should be selected Any materials used should be assessed forchemical stability under the effects of high heat moisture and hydrocarbon contamination The means ofcorrosion control selected for the concrete substructure (such as cathodic protection) should be clearlycommunicated

F 400 Topsides - substructures mating

401 While the selection of an installation method affects both substructure and topside design one mustensure that such consequences are addressed at an early stage

402 Typical items and effects to be considered are

mdash dynamic response to waves and currents of the submerged structure if a float-in installation is requiredmdash dynamic response to wave winds and currents of a partially submerged substructure for a lift installation

of topsidesmdash design of installation aids for both lift and float-in installations

Sufficient tolerances shall be incorporated in the design for the mating operation

F 500 Transportation

501 The dynamic motions during the towage of fixed concrete installations are usually small Accelerationsand tilting angles in the intact and damaged condition shall be accurately defined Consequences for design oftopside substructure and their connections shall be addressed

G Barges

G 100 General

101 Barges classed by DNV shall be designed and constructed in accordance with DNV Rules forClassification of Ships Pt5 Ch7 Sec14 Concrete Barges

SECTION 6DETAILED DESIGN OF OFFSHORE CONCRETE STRUCTURES

A General

A 100 Introduction101 This detailed Standard for design of Offshore Concrete Structures is prepared based on more than 30years of experience with design of Offshore Concrete Structures These structures can be any type of structure(ground supported and floating) including shell type structures exposed to extreme environmental waveloading102 The first DNV Standard for Design of Offshore Concrete Structures for Oil Production Platforms wasissued in 1974 This Standard was later updated in 1977 1992 2004 and 2007 The latest issue of NorwegianStandard NS3473 rev 5 ldquoConcrete Structures ndash Design Rulesrdquo was issued in November 1998 This standardwas withdrawn in March 2010103 Other design standards may be used as an alternative for detailed design of Offshore Concrete Structuresdue to local preferences An opening for this is given within this standard provided the requirements to thedetailed standard given in Appendix D are sufficiently covered The level of safety shall be as required by DNVstandard The compliance with this requirement shall be documented

A 200 Material201 The requirements to materials given in Section 4 shall apply for structures designed in accordance withthis section202 For definition of normal strength concrete high strength concrete and lightweight concrete see Sec4C100

A 300 Load effects301 Load effects shall be calculated in accordance with the methods outlined in Section 5 Cracking of theconcrete where that has a significant influence on the load effects shall be taken into account302 In slender structures the effect of the structural displacements shall be accounted for in the calculation offorces and moments (2nd order effects)303 Load effects from imposed deformations shall be considered when relevant Restraint forces caused byimposed deformations such as support settlements imposed or restrained axial deformations rotation etc shallbe considered When calculating the action effects due to restraint forces potential cracking may be consideredin accordance with O800 In the ultimate limit state the non-linear behaviour of the structure may be consideredin the calculation of the effects of imposed strains and deformations304 The capacity of a structure may be checked by assuming plastic regions in the calculation of forces andmoments It shall be demonstrated that the necessary displacements are possible in these regions305 Moments and shear forces from concentrated loads on slabs can be calculated assuming a load spread of45deg from the loaded surface to the reinforcement on the opposite side of the slab306 Calculation of load effects in shear walls and shells may be based on assumptions other than the theoryof elasticity if sufficient knowledge on the stress conditions of the actual structure is available based on testsor nonlinear calculations Force models as indicated in I ldquoRegions with Discontinuity in Geometry and Loadsrdquomay be used if relevant models can be established for the structure in question307 Unless otherwise documented pressure from liquids and gases is in addition to acting on the surfacealso assumed to act internally on the entire cross section or in the cracks whatever is the most unfavourable308 In structural analysis of FRP reinforced structures non-linear redistribution of internal force resultantsis not accepted due to the linear stress-strain curve of FRP reinforcement309 For FRP reinforced structures force models as indicated in I ldquoRegions with Discontinuity in Geometryand Loadsrdquo shall be applied with care allowing no redistribution in the FRP reinforcement

A 400 Effective flange width401 A cross section subjected to bending with a flange in the compression zone may be assumed to have aneffective flange width on each side outside the web equal to the smallest of the following values

mdash actual width of flangemdash 10 of the distance between the beams points of zero momentmdash 8 times the flange thickness

402 If the flange has a haunch of width exceeding the height of the flange the effective flange width may beincreased by the height of the haunch but shall not exceed the actual width of the flange

403 In a cross section with flange on only one side of the web and not braced laterally skew bending andtorsion shall be considered Furthermore effective flange width shall not exceed 75 of the distance betweenthe beam points of zero moment404 If the flange is located in the tension zone the reinforcement located inside a width as given for acompression zone may be considered fully effective405 Values documented by more accurate calculations may be used instead of those given above

A 500 Composite structures501 Composite structures are structures where concrete and structural steel act together Steel and concretemembers shall be designed in accordance with DNV-OS-C101 and this standard respectively or otherInternational applicable standards The same safety level shall be achieved as in this standard The generalrequirements of this standard still apply502 A composite structure can be assumed to perform as a monolithic unit if the shear forces betweenmembers of the composite can be transferred by reinforcement shear keys or by other devices The force inthe shear connectors shall be calculated in accordance with an International recognized standard for compositestructures503 In the ultimate and fatigue limit states forces shall be calculated considering the characteristics of theconnection ie fully or partially bonded between members of the composite 504 The capacity of the individual structural members of the composite structure shall be also checked forthe loads applied on the members before they are acting as a unit In the serviceability limit state it shall beconsidered whether the respective loads are applied before or after the members are acting together505 Composite member deflection may be estimated assuming a cracked concrete section to calculate thesection moment of inertia The height of the concrete compression zone shall be calculated based on the actingloads

Composite structures with studs506 Material factor for studs may be assumed equal to the material factor for steel reinforcement Table B1507 Studs may be considered to contribute to the shear capacity of the concrete component provided that theyextend through the concrete core and meet the requirements for transverse shear reinforcement stated in FContribution from studs to the shear capacity of the concrete component may be calculated according to F508 Studs shall be designed for the combination of shear stresses caused by the shear transverse force in theinterface between concrete and steel and the normal stresses in case studs are assumed to contribute to theshear capacity of the section509 Studs shall not crush the concrete in their vicinity

Guidance noteThis is ensured by limiting the shear stresses in the studs

where

D = Diameter of studs (mm)Ecn = Youngrsquos modulus of concrete taken as the secant value between σc = 0 and 04 fcck (MPa)fcck = Characteristic cylinder compression strength of concrete (MPa)α = 02 (hsD + 1) le 1 where hs is the stud height (mm)γs = Material factor for steel studs τs = Shear stress in the studs (MPa)

Studs shall not be placed at a distance longer than 22 times th times (235fyk-p)05 at the steel plate in compression in order toavoid plate buckling where fyk-p is the characteristic yield stress of the plate

510 S-N curves used for the fatigue limit state check of steel members and studs shall be documentedconsidering the influence of the connection between studs and steel members eg type of welding

A 600 Prestressed structures with unbonded tendons601 Un-bonded tendons for prestressed structures may be used provided that corrosion protection isadequately documented and a risk assessment of accidental situations that may result in the sudden failure ofthe un-bonded tendon is carried out602 The risk assessment of accidental situations shall include the evaluation of the consequences of thefailure of the tendon itself ie risk of hitting people structure equipment etc by the sudden failed tendonsand the potential collapse of the structure due to the loss of prestressing force

2

502

250

)(290

D

EfD

s

cnccks timestimestimes

timestimesleπγ

ατ

603 Design shall account for the effects of the use of un-bonded tendons on the structural performance crackwidth distribution development of forces in the tendons etc

A 700 Yield line theory

701 Yield line theory may be used as the basis for design in the ULS and ALS conditions provided thefollowing conditions are satisfied

mdash The load carrying capacity is governed by a ductile mode of failure (structural detail has sufficient capacityin shear and moment to accommodate the required rotation)

mdash Second order effects are negligible (No buckling mode of failure)mdash The plastic hinges along the yield lines will allow sufficient rotation prior to structural failure of the hinge

Compliance with the above requirements shall be documented

702 Redistribution of shear and moment caused by presumed yielding of FRP is not accepted Rotations arecaused by cracking and compression failure in the concrete

B Design Principles

B 100 General

101 Design in compliance with this standard can be based either on calculations or on testing or acombination of these

B 200 Limit states

201 Structures shall satisfy the requirements in the following limit states

mdash ultimate limit state (ULS)mdash accidental limit state (ALS)mdash fatigue limit state (FLS)mdash serviceability limit state (SLS)

202 In ULS and ALS the capacity is demonstrated by testing or by calculation based on the strain propertiesand design material strengths

203 In FLS it shall be demonstrated that the structure can sustain the expected load cycles at the applied loadlevels for the intended service life

The documentation shall include

mdash bending momentmdash axial forcemdash shear forcemdash torsional momentmdash anchorage of reinforcementmdash partial loading

and combinations of these

204 The design in SLS shall demonstrate that the structure during its service life will satisfy the functionalrequirements related to its use and purpose Serviceability limit state requirements shall also ensure thedurability and strength of the structure

The documentation should include

mdash cracksmdash tightnessleakagemdash strainsmdash displacementsmdash dynamic effects

205 No yield in the reinforcement is allowed for temporary phases for structural elements exposed to marineenvironment for possible loads with ɣf = 10 No reduction in environmental load

206 Oil containment structures shall be designed for all possible load conditions with ɣf = 10 for all possibleload including extreme environmental loads There shall be no yield in the reinforcement under this condition

207 Oil containment structures shall also be designed for all possible loads that can occur from the extremeenvironmental load until all the oil is safely removed with ɣf = 10 on all loads The structure shall have acompression zone of minimum 100 mm under this load condition The structural analyses shall be made on thedamaged structure

B 300 Characteristic values for material strength301 The characteristic strength of materials shall be determined according to design standards and recognizedstandards for material testing (ASTM ACI EN ISO) 302 The in-situ strength fcn of concrete grout fibre reinforced concrete and fibre reinforced grout may bedetermined from the characteristic compressive strength fcck as follows (see Sec4 C to F)

fcn = fcck middot (1-fcck600)303 For geotechnical analyses the characteristic material resistance shall be determined so that theprobability of more unfavourable materials occurring in any significant extent is low Any deteriorating effectsduring the operation phase shall be taken into consideration See DNV-OS-C101304 For fatigue limit state FLS the characteristic strength of soil shall be used For other materialsacceptance criteria shall be specified which offer a safety level equivalent to that of the present provision305 Where high resistance of a member is unfavourable (eg in weak link considerations) an upper value ofthe characteristic resistance shall be used in order to give a low probability of failure of the adjoining structureThe upper value shall be chosen with the same level of probability of exceedance as the probability of lowervalues being underscored In such cases the material factor shall be 10 in calculating the resistance that isapplied as a load on adjoining members

B 400 Partial safety factors for materials401 The partial factors for the materials γm in reinforced concrete structures (concrete steel and FRPreinforcement grout fibre reinforced concrete and fibre reinforced grout) shall be chosen in accordance withthis standard and for the limit state considered In addition material factors for FRP reinforcement aredependent on the duration of the load under consideration402 For structural steel members the material factor shall be in accordance with DNV-OS-C101403 Foundation design shall be performed with soil material factors in accordance with DNV-OS-C101Section 11

B 500 Design by testing501 If the loads acting on a structure or the resistance of materials or structural members cannot bedetermined with reasonable accuracy model tests can be carried out Reference is made to P502 Characteristic resistance of structural details or structural members or parts may be verified by acombination of tests and calculations503 A test structure a test structural detail or a test model shall be sufficiently similar to the installation to beconsidered The results of the test shall provide a basis for a reliable interpretation in accordance with arecognized standard

C Basis for Design by Calculation

C 100 Design material strength101 The material coefficients γm take into account the uncertainties in material strength and cross-sectionaldimensions among others The material coefficients are determined without accounting for reduction ofcapacity caused by corrosion or mechanical deterioration

102 The material coefficients γm for concrete and steel reinforcement are given in Table C1

103 The in-situ compression strength fcn and tensile strength ftn of normal weight concrete grout fibrereinforced concrete and fibre reinforced grout shall be determined according to Sec4 C to F

104 If the design is carried out by testing the requirements given in P500 shall apply

105 When high concrete design strength is unfavourable a special appraisal of the material coefficients andthe nominal value of the in-situ strength shall be performed

106 For reinforcement consisting of FRP bars consistent sets of characteristic material parameters andmaterial factors for each limit state which have been determined by a formal qualification process accordingto DNV-OSS-401 shall be used for design Material factors for strength and stiffness for the different limitsstates shall be reported in the Material Certificate

107 For FRP reinforced structures the ultimate limit state shall be checked for the appropriate loadcombinations according to Section 5 using a material factor for strength that reflects the duration of the extremeload in each load combination as well as effects of embedment and alkali exposure The effect of temperatureis covered by the temperature conversion factors mentioned in Sec4 I405

108 The load durations considered in design for FRP reinforced structures shall not be less than thosespecified Table C2 for the applicable limit states according to Sec5 Table D2

The material coefficients γm for FRP reinforcement are given in Table C2

109 For fatigue limit state a material factor γFSSA which accounts for the duration of the loading shall beused The load duration used in the damage accumulation shall not be taken less than 5 years in each stressblock

110 For ALS a material factor for strength γFA taking account of the duration of the relevant accidentscenarios shall be used for FRP reinforcement with due consideration of the consequences of the accident andthe duration of these consequences The duration should in general not be taken less than 24 hours see C113

Table C1 Material coefficients for concrete and reinforcementLimit States Ultimate

ULSFatigue

FLSAccidental

ALSServiceability

SLSReinforced concretegrout3 (steel) γc 1351 (150)2 1351 (150)2 1101 (120)2 100

Steel reinforcement γs 1101 (115)2 1001 (110)2 1001 (110)2 100Plain concretegrout fibre reinforced concretegrout γc 150 150 120 100

1) When the design is based on dimensional data that include specified tolerances at their most unfavourable limits structural imperfections placement tolerances as to positioning of reinforcement then these material coefficients can be used When these coefficients are used then any geometric deviations from the ldquoapproved for constructionrdquo drawings must be evaluated and considered in relation to the tolerances used in the design calculations

2) Design with these coefficients allows for tolerances in accordance with C500 or alternatively on cross sectional dimensions and placing of reinforcements that do not reduce calculated resistance by more than 10 If specified tolerances are in excess of those given in C500 or the specified tolerances lead to greater reductions in calculated resistance the excess tolerances or the reduction in excess of 10 shall be accounted for in resistance calculations Alternatively material coefficients may be taken according to those given under 1

3) Material factors for reinforced grout may be used in design where the grout itself is reinforced by steel reinforcement or where it can be demonstrated that steel reinforcement or anchor bolts in the surrounding structure contribute to reinforce the grout (such as grouted connection type B in Sec6 T800)

Table C2 Material coefficients for FRP reinforcement

Load combination type DurationLoad combination according to Sec5

Table D2

Material factor3 for strength

I Permanent load + live loads of permanent character1 50 years c γFI

III + extreme value of live loads of variable character2 (eg weight of occupants) 1 year d e γFII

IIIII + extreme value of environmental load (wind waves current) 1 week a γFIII

1) Live loads of permanent character are live loads that the structure may be exposed to for its entire service life or a considerable part of it eg load from prestressing dead weight of the structure weight of furniture stored goods etc

2) Live loads of variable character are live loads that the structure can be exposed to only for limited durations much less than the service life such as eg weight of occupants and (not permanently stored) vehicles

3) Values for γFI γFII and γFIII shall be calculated as described in C113

Temperature loads may be either type II or III depending on duration of the temperature load

For SLS a material factor for strength γFS taking account of the design life of the structure shall be used forFRP reinforcement see C113

111 Design values for the concretegrout are

Ecd = Ecn γcEcn = 22 000 middot (fcck10)03 MPa for fcck lt 65 MPaEcn = 4800 middot (fcck)05 MPa for fcck gt 65 MPafcd = fcn γcftd = ftn γc

where

Ecd = Design value of Youngrsquos Modulus used in the stress-strain curveEcn = Normalized value of Youngrsquos Modulus used in the stress-strain curve fcck = Characteristic compressive cylinder strengthfcd = Design compressive strengthfcn = Normalised compressive strength see 103ftd = Design strength in uni-axial tensionftn = Normalised tensile strength see 103γc = Material factor (Table C1)

112 Design values for the steel reinforcement are

Esd = Esk γsfsd = fsk γs

where

Esd = Design value of Youngrsquos Modulus of reinforcementEsk = Characteristic value of Youngrsquos Modulus of reinforcementfsd = Design strength of reinforcementfsk = Characteristic strength of reinforcementγs = Steel reinforcement material factor (Table C1)

113 Design values for FRP bar reinforcement are

EFd = EF γFEfFd = fF γm

where

γFE = Material factor for Youngrsquos modulus EF which accounts for long term creep effects in the bars γm = Material factor for strength of FRP reinforcement bars taking into account the duration of Loading

service temperature as well as manufacturing and placement considerations For implementation of γmin ULS ALS and SLS see below

γm for FRP bars in the Ultimate Limit State (ULS)

γm shall be implemented in design in ULS as γFI γFII or γFIII depending on the load combination type specifiedin Table C2 under consideration It is a function of

mdash γF a material factor to account for statistical variation in the material strength potential placementinaccuracy in the section due to the physical characteristics of the bars and the level of control implementedduring manufacturing and

mdash ηF TTR derived from the characteristic time to rupture curve for the load durations for the different loadcombination types

γm = γF middot ηT middot ηF TTR

where

γF = 125 for Certified bar products meeting all manufacturing QA QC requirements specified inAppendix G produced under an established certification scheme

= 140 for Certified bar products meeting all manufacturing QA QC requirements specified inAppendix G during initial establishment period of the certification scheme

ηT = Service temperature conversion factor See Sec4 I405ηF TTR = (fF fF TTR(i))

where

fF = Characteristic short term tensile strength (force per area) of FRP barfF TTR(i) = Characteristic tensile strength (force per area) in FRP bar until failure at considered load duration

i to be documented through extrapolation of TTR test data i = I (50 years) II (1 year) or III (1 week) corresponding to the load durations as per Table C2

γm for FRP bars in the Accidental Limit State (ALS)γm shall be implemented in design in ALS as γFA it is a function of

mdash ηF TTR derived from the characteristic time to rupture curve for the expected accidental load duration andassociated consequences

γm = γFmiddot ηT middot ηF TTR

where

γF = 12 ηT = Service temperature conversion factor See Sec4 I405ηF TTR = (fF fF TTR(i))

where

i to be documented through extrapolation of TTR test data i = Expected duration of the accidental scenario and consequences under consideration Shall not be

taken to be less than 24 hours

γm for FRP bars in the Serviceability Limit State (SLS)γm shall be implemented in design in SLS as γFS it is a function of

mdash ηF TTR derived from the characteristic time to rupture curve for the load duration relating to the design lifeof the structure

where

i to be documented through extrapolation of TTR test data i = Duration corresponding to the design life of the structure Shall not be taken to be less than 50

years see Sec2 B107 and B108114 Stress-strain relationship for concrete or grout in compression of a specified grade shall be chosen suchthat it results in prediction of behavioural characteristics in the relevant limit states that are in agreement withresults of comprehensive tests In lieu of such data the general relationship given in Figure 1 may be used

Figure 1 General stress-strain diagram for calculation of resistance of normal dense aggregate concrete incompression

Note Compression is defined as negative and hence the values of ε and σ are negative for concrete subject tocompression

For

then

For

then

For

then

where

For normal dense aggregate concretegrout where fcck le 65 MPa it may be assumed that

For normal dense aggregate concretegrout where fcck gt 65 MPa it may be assumed that

-06f cn

cr-f

-fcn

σc

εcn-06f Ecncn coε cuε

cnf γm

εc (-)

cocuc εεε lelt

cnc fminus=σ

cn

cnccu E

f60minuslelt εε

( ) ( )1

60

601

minusminus

minus+minus+=

m

cn

cnccncnccnc fm

fEfmE

εεσ

060 ltleminus

ccn

cn

E

f ε

)( cncu m εε 5152 minus=

cn

cncn E

fminus=ε

minus=

600

1 cckcckcn

fff

cn

comεε

=

30

1022000

= cck

cn

fE MPa

( ) 504800 cckcn fE = MPa

where

ε1 = - 19 permil and ke = 0004 permilMPa

115 For concrete grades gt C65 and for all lightweight aggregate concretes the values of Ecn and εco shall bedetermined by testing of the type of concrete in question Concrete subject to tensile strains shall be assumedstressless if not otherwise stated

116 For fibre reinforced concrete of all grades the values of Ecn and εco shall be determined by testing of thetype of fibre reinforced concrete in question Concrete subject to tensile strains shall be assumed stressless ifnot otherwise stated

117 For normal dense concrete of grades between C25 and C45 the following simplified stressstraindiagram may be used

Figure 2 Simplified stress-strain diagram for normal density concrete of grades between C25 and C45 subject tocompression

εco = - 2permil is strain at the point of maximum stress

118 For lightweight aggregate concrete of grades between LC25 and LC35 a simplified bilinear stress ndashstrain diagram may be applied for calculation of capacities

The maximum strain limit for lightweight aggregate concrete in compression is

where ε1 = - 35permil ρ1 = 2200 kgm3 and ρ = density of lightweight aggregate

Figure 3 Simplified stress-strain diagram for lightweight aggregate concrete of grades between LC25 and LC35

= -20

-fcr

σ

εcεco -35(permil)

σc

0

c

minusminus=

co

c

co

ccdc f

εε

εεσ 2

+=

11

7030

ρρεε cu

σc

(permil)εcεcu-200

-fcr

119 Prior to using non-standard lightweight concrete or lightweight composite concrete in a structure orbarge the stress strain relationship till failure shall be documented120 For calculation of capacities for axial forces and bending moments different stress distributions fromthose given herein (C114 C117 and C118) may be applied as long as they do not result in a higher sectionalcapacity

C 200 Stress strain curve for structural grout and fibre reinforced grout201 For structural grout and fibre reinforced grout with characteristic cylinder strength larger than 65 MPathe values of Ecn and εco shall be determined by testing of the type of grout in question Grout subject to tensilestrains is to be assumed stressless if not otherwise stated

Guidance noteAs a guideline Ecn may be taken as 4800 middot (fcck)05 For structural grout with strength larger than 65 MPa the stress-strain curve may be presumed linear until failure

C 300 Steel reinforcement stress ndash strain curves 301 For steel reinforcement a relationship between force and strain which is representative for the type inquestion shall be usedThe stress-strain diagram for design is found by dividing the characteristic strength fsk by the materialcoefficient γs302 Where the assumed composite action with the concrete does not impose stricter limitations the strain inthe reinforcement shall be limited to εsu equal to 10permil For prestressed reinforcement the prestressing strain isadded to this limit303 For reinforcement in accordance with Section 4 the steel stress may be assumed to increase linearly from0 to fsd when the strain increases from 0 to εsy = fsk EskThe reinforcement stress may be assumed to be equal to fsd when the strain varies between εsy and εsu The steel can be assumed to have the same strain properties and yield stress in both compression and tensionIf buckling of steel reinforcement in compression is expected to occur properties in compression shall bemodified accordingly304 For temperatures above 150degC the stress-strain diagram for ribbed bars in accordance with Section 4 canbe assumed to be in accordance with Figure 4 for steel reinforcement

Figure 4 Stress-strain diagram for steel reinforcement in accordance with Section 4

σ

0

skf

c

εε (permil)c

sy suε =100

sdf

Figure 5 The relation between stress and short-term strain for ribbed bars at temperatures above 150degC

The diagram in Figure 5 does not include thermal strain or creep strain caused by high temperature

305 Steel reinforcement exposed to low temperature shall remain ductile under the applicable temperaturerange For reinforcement subjected to cryogenic temperatures such as for LNG applications reference is madeto DNV-OS-C503

C 400 FRP reinforcement stress ndash strain curves

401 The design Youngrsquos modulus of FRP reinforcement bars is defined as EFd

402 The stress-strain curve for FRP reinforcement in tension shall be considered as linear until failure at adesign strength of fFd The value of fFd depends on the duration of load combinations defined in Table C2

403 FRP reinforcement shall not be considered to work in compression

404 The impact of temperature on the strength of the FRP reinforcement shall be considered in design seeSec4 I405 for more details

C 500 Geometrical dimensions in the calculation of sectional capacities

501 When allowing larger deviations in dimensions than those specified in Table C3 the deviations insectional dimensions and reinforcement position shall be considered in the design Smaller deviations than thespecified tolerances may be considered

For structures of special shapes and geometry alternative tolerances may be specified from a strength point ofview provided the capacity calculated based on the specified tolerances does not reduce the capacity with morethan 10

502 If the most unfavourable combination of specified tolerances for sectional dimensions and reinforcementpositions are considered and conformity control subsequently verifies that the actual deviations exceed thosespecified then the increased material coefficients in accordance with Table C1 shall be used

Table C3 Acceptable DeviationsType of Dimensional Deviation Maximum Tolerance

Overall dimension plusmn 25 mmCross-sectional plusmn 8Perpendicularity 8 permilInclination 3 permilLocal variations (1 m measuring length) 8 mmLocal variations (2 m measuring length) 12 mm

10 2 3 4 5 6 7 8

02

04

06

08

10

0 sε εsy

f sy

σs

f and denotescharacteristic yieldstress and yieldstrain at 20degC

sy syε

20degC300150200400

500

600

700

Should the As-Built documentation show that the intended deviation in tolerances are not met then the sectionshall be re-evaluated in all relevant limit states

503 For structures cast under water the outer 100 mm of concrete at horizontal construction joints and in thecontact area between the ground and the concrete shall not be taken into account as effective cross section fortransfer of forces If the structure is set at least 100 mm into rock the entire concrete section can be calculatedas effective for transfer of forces to the ground

C 600 Tension in structural members

601 Tensile forces shall be provided for by reinforcement with the following exceptions

mdash Tension caused by shear force anchorage or splicing of reinforcement and by partially loaded areas if noincrease in the concrete strength is considered which may be assumed transferred by the concrete by designin accordance with this standard

C 700 Creep effects

701 Creep effects shall be considered where relevant Rough estimates of creep effects may be obtained bymethods originally developed for simple columns Two methods are referred to the so-called ldquocreep factormethodrdquo and the ldquocreep eccentricity methodrdquo

Figure 6 Modified stressstrain Relationship for Concrete

Guidance noteldquoCreep factor methodrdquo The method utilizes a modified stressstrain diagram for concrete In this diagram the shortterm strains are multiplied by (1 + ϕ) ϕ being the creep factor see Figure 1 and Figure 6The values of ϕ shall be carefully determined in accordance with recognized principles The creep factor ϕ shall bedetermined for relevant temperature range concrete grade and humidityldquoCreep eccentricity methodrdquo In this method the effect of creep is accounted for by introducing an additionaleccentricity caused by creep The method is convenient to use Two important conditions with respect to applicationof the method shall be noted

- The total eccentricity shall be small enough so that cracking is avoided- The value of the load causing creep shall be small enough so as to avoid non-linear material behaviour under short

term loading

C 800 Effect of water pressure

801 The effect of hydrostatic pressure on the concrete strength shall be evaluated where relevant Forlightweight aggregate concrete this effect may be significant

D Bending Moment and Axial Force (ULS)

D 100 General

101 The capacity for bending moment and axial force can be determined by assuming that plane crosssections remain plane after straining and that the stress and strain properties of the concrete and thereinforcement are as given in C

-σ

0

c-f

c

(-)ε

εcu

cεco

Original Modified

coε (1+ϕ) (1+ϕ)εcu(See fig1for symbols)

When load effects are determined by applying plastic design analysis techniques Such structures shall becomposed of members that are able to develop well-defined plastic resistances and maintain these resistancesduring the deformation necessary to form a mechanism The plastic resistances shall be adequatelydocumented see A700102 Load effects determined by applying plastic design analysis techniques shall not be applied in FRPreinforced structures The average calculated compressive strain over the cross section shall not exceed(εco + εcu)2 Strain caused by shrinkage and linear creep shall be added and the total strain shall be within theabove limit103 When calculating the capacity of a cross section resulting from an external axial load the axial load shallbe assumed to have a minimum eccentricity about the most unfavourable principle axis The eccentricity shallnot be taken less than the largest of 20 mm or 130 of the cross-sectional dimension in the direction of theeccentricityThe requirements given in this sub-section are in general applicable to structural members where the ratiobetween the depth h of the member and the distance between the points of zero bending moment is less than05 If this ratio is greater than 05 assumptions relevant to other types of structural members such as deepbeams corbels etc shall be applied104 If the area of compressive reinforcement exceeds 4 of the concrete area the capacity calculation shallbe based on the net area of concrete The net area of concrete is defined as the concrete area between the centroid of the reinforcement on ldquotensilerdquoand ldquocompressionrdquo side of the member For members reinforced using bundled bars the centroid refers to thecentroid of the bundle For members with several layers of reinforcement the centroid refers to the outer baron the ldquotensilerdquo and ldquocompressionrdquo side105 In axially loaded structures such as columns and walls the reinforcement shall only be consideredeffective in compression if sufficiently secured against buckling The compressive reinforcement shall bebraced by crossing bars placed on the exterior side unless otherwise is shown to be sufficient106 For columns with spiral reinforcement as described in Q1009 and with normal weight concrete of gradesno higher than C45 the sectional resistance capacity can be calculated in accordance with this clauseThe axial capacity shall be calculated using an effective cross section defined as the concrete core inside thecentroid of the spiral reinforcement plus the equivalent concrete cross section of the longitudinal reinforcementbased on modular ratios of concrete and reinforcement For eccentricities less than 025Dk an increasedcompressive design strength of the concrete can be assumed equal to

where

mdash s is the centre to centre distance between the spiral reinforcement measured in the longitudinal directionof the column

mdash Dk is the diameter of the concrete core inside the centroid of the spiral reinforcement Ass mdash fssd is the design strength of the spiral reinforcement Ass mdash e is the eccentricity of loading

The strains εco and εcu shall be assumed to increase at the same ratio as the design strengthThe capacity shall neither be taken as less than the capacity of the full cross section including the longitudinalreinforcement without adding for the effect of the spiral reinforcement nor more than 15 times this capacity107 The capacity of an unreinforced cross section shall be determined with the concrete stress-strainrelationship given in C114 assuming the concrete not to take tensionThe eccentricity shall not be larger than to give a compressive zone of at least a half of the cross sectional depth108 The tensile strength for fibre reinforced concrete containing at least 1 volume per cent steel fibre can betaken as kw ftd For design of cross sections subjected to axial tension the factor kw shall be taken as 10 whendesigning for bending moment or bending moment in combination with axial compression the factor kw shallbe set at 15 ndash hhl but no less than 10 h = the cross-sectional height and h1 = 10 m

E Slender Structural Members

E 100 General101 For structural instability a simplified method of analysis will in general be considered acceptable if itcan be adequately documented that for the relevant deformation the design loading effects will not exceed the

sdotminussdotsdotsdotsdot+

kk

ssssdcd D

e

sD

Aff

416

corresponding design resistances for structural instability General non-linear analyses are described in Sec5E1200Slender structural members subjected to axial compression or bending moment in combination with axialcompression shall be dimensioned for these action effects and the effect of displacements of the structure(second order theory) The effect of concrete creep shall be accounted for if it has an unfavourable influenceon the capacity 102 Displacements caused by short-term actions shall be calculated in accordance with the stress-strain curvegiven in C100103 The effect of creep shall be calculated in accordance with the history of actions on the structure andcharacteristic actions see also Sec5 E300104 A structural member shall be assumed as slender if in accordance with E110 to E112 the effect ofdisplacements cannot be ignoredWhere second order effects may be significant such effects shall be fully considered The design ofneighbouring elements shall take into account possible second order effects transmitted at the connections105 Structures structurally connected with slender compressive members shall be designed for forces andbending moments in accordance with the assumed degree of restraint and the additional moments caused bythe displacements in the connecting membersThe stiffness assumptions for the individual structural members shall be in accordance with the design actioneffects and the corresponding state of strainReinforcement at least equal to what was assumed when calculating the displacements shall be provided in thestructural members106 The compressive force in slender compression members shall be assumed to have an unintendedeccentricity calculated in accordance with specified tolerances for curvature and inclination for the individualmembers107 The eccentricity shall not be assumed to be less than the largest of 20 mm le300 or 130 of the crosssectional dimension in the direction of eccentricity unless special conditions provide basis for other valuesThe buckling length le is the length of a pin connected strut with the same theoretical buckling force (Euler-force) and direction of displacement as the structural member in question108 The unintended eccentricity shall be assumed to act along that principal axis of the cross section wherethe effect will be most unfavourable considering simultaneously the effect of first and second order bendingmoments109 The geometrical slenderness λ shall normally not exceed where

As = the area of reinforcementAc = the cross-sectional area of un-cracked concrete

The force dependent slenderness λN of a structural member is calculated from the equation

whereλ = le i i =

Ic = the moment of inertia of AcNf = design axial forcele = effective length theoretical buckling length

The reinforcement area As is introduced with its full value for rectangular sections with reinforcement in thecorners or with the reinforcement distributed along the faces perpendicular to the direction of the displacementFor other shapes of cross-sections or other reinforcement positions the reinforcement area can be entered astwo thirds of the total reinforcement area if more accurate values are not used110 The force dependent slenderness in the direction with the smallest resistance against buckling shallnormally not be greater than 45

tω4180 +

sdotsdot=

ccd

csd

Af

Afω

t

fn

n

ωλλ

41+minus

=

cc AI

ccd

ff Af

Nn

sdot=

)()( ccdssdt AfAf=ω

111 The effect of displacements may be neglected if the force dependent slenderness λN based on the designactions is less than 10112 For a structural member with braced ends without lateral forces this limit may be increased to

λN = 18 - 8 | MOA | | MOB |where

| MOA | = Numerical smallest member end moment calculated from 1st order theory| MOB | = Numerical largest member end moment calculated from 1st order theory

if the structural member is designed over its entire length for the numerically largest end moment calculatednot considering the displacements (first order theory)The ratio MOAMOB is the ratio between the numerically smallest and largest end moment calculated notconsidering the displacements (first order theory) The ratio shall be entered with a positive value when the endmoments give tension on the same side of the member (single curvature) and with a negative value when theopposite is the case (double curvature)If the largest end moment is less than that resulting from the smallest eccentricity in accordance with E107 theratio shall be set to 10113 If the force dependent slenderness calculated with axial forces based on the characteristic long-term forcefor the structure and the corresponding end moments does not exceed the values given in E109 The effect ofcreep may be ignored

114 Beams and columns in which due to the slenderness considerable additional forces may occur due to torsionaldisplacements of the structural member (lateral buckling or torsional buckling) shall be designed accordingly115 When designing thin-walled structures consideration shall be made to local displacements where thiswill influence the design action effects The calculation shall be based on approved methods and the principlesgiven in E101 to E110 where these apply116 If vital parts of the structure are in flexural or axial tension and redistribution of forces due to crackingis expected detailed non-linear (geometrical and material non-linearities) analyses of the reinforced concretemay be required

F Shear Forces in Beams and Slabs

F 100 Basis101 The rules in this sub-section apply to beams slabs and members where the ratio between span length anddepth is at least 30 for two-sided supports and at least 15 for cantilevers Structural members having a smallerratio between length and depth shall be designed in accordance with I102 The capacity with respect to tensile failure (Vcd + Vsd) and compressive failure (Vccd) shall be checkedThe calculation may be performed in accordance with the simplified methods in F200 truss model method inF300 or the general method given in H

103 In the case of haunches or prestressed reinforcement that are inclined compared to the longitudinal axisof the structural member the component of forces perpendicular to the longitudinal axis shall be added to thedesign shear forces from the actions If forces or support reactions are applied to the structural member in sucha manner that internal tensile forces are imposed in the direction of the force these internal forces shall betransferred by reinforcement104 In support regions an internal force system shall be chosen in accordance with Sec6 I Tensile failure capacity for direct force applied within a distance a le 2d from the face of the support may as asimplification be checked by demonstrating that the cross section has sufficient capacity for a part of the loadequal to the load multiplied by the factor a2d when determining the shear forcewhere

a = distance from the face of the supportd = distance from the centroid of the tensile reinforcement to outer edge of the compression zone

For distributed actions which are nearly uniform the value of the shear force at the distance d from the face of supportmay as a simplification be used to check the capacity for tensile failure in cross sections closer to the supportThe capacity for compressive failure shall be verified at the face of the support for the entire shear force105 Shear reinforcement shall be included in the calculations of the capacity only if the providedreinforcement is at least as given in Q906 and shall consist of stirrups or bent bars In beams at least half of theshear capacity to be provided by shear reinforcement shall be stirrupsThe spacing between the stirrups measured along the longitudinal axis shall not be more than

06middot h(1 + cot α) le h and not more than 500 mm see Q906 Only shear reinforcement of an angle between 45and 90 degrees with the longitudinal axis shall be included in the calculations Inclined shear reinforcementshall be slanted to the same side of the cross section as the principal tensile stresses The spacing between thestirrups shall neither exceed 04 h middot (1 + cot α) nor 07 middot h if the shear force is greater than 2 middot ftd middot bw middot d or ifin combination with shear force there is significant axial tension or if the action has fatigue effectPerpendicular to the span direction of the structural member the spacing shall neither exceed the depth of thebeam nor be more than 600 mm

where

α = the angle between shear reinforcement and the longitudinal axishrsquo = the distance between the centroid of the reinforcement on the ldquotensilerdquo and ldquocompressionrdquo side of the

member

106 For slabs the capacity in any direction shall at least be equal to the design shear force for this directionIf the capacity is not sufficient without shear reinforcement the area of shear reinforcement for the directionthat has the greatest requirement shall be provided

If the action is transferred to the supports primarily in one direction it is sufficient to check the shear capacityfor this direction

If the slab is not subjected to in-plane membrane forces the slab can be designed for the principal shear forceat the considered position

107 A beam flange subjected to shear forces in its plane can be designed in accordance with the rules forcombined action effects in H or I

108 FRP bars used for shear reinforcement shall be placed perpendicular to the member longitudinal axisConsequently the angle α between the shear reinforcement and the longitudinal axis in F105 shall be taken as90 degrees

109 FRP reinforcement may be used as shear reinforcement in reinforced concrete structures A maximumstrain shall be utilized in the shear strength calculation when using the simplified method in F200

Guidance noteA recommended value for maximum strain to be utilized in shear strength calculations is 4permil

110 When designing members with FRP shear reinforcement the provisions of F200 and F300 shall apply

As and ASV shall be replaced by AF and AFV respectively in the design formulations

111 When using the truss model method described in F300 the maximum stress fFb in the prefabricated shearreinforcement is

fFb = ηb f F d

where

fFb = design tensile strength of the bend of FRP barηb = experimentally determined conversion factor for bends

fFd is design tensile strength of straight FRP reinforcement for appropriate load combination defined in Section 5

F 200 Simplified method

201 For a structural member without shear reinforcement the shear capacity at tensile failure can be taken asVcd The capacity for shear force without a coinciding axial force can be taken as

where

As = the cross section area of properly anchored reinforcement on the tension side (mm2)bw = width of beam (mm)d = distance from centroid of tensile reinforcement to compression edge (mm)d1 = 1 000 mmkA = 100 MPakv = For slabs and beams without shear reinforcement the factor kV is set equal to 15 ndash dd1 but not greater

than 14 nor less than 10

vwtdVwwc

sAtdcocd dkbfdkb

db

AkfVV 6030 le

+==

γ

202 The capacity at tensile failure for shear force in combination with axial compression may be taken as

where

Mo = -Nf middot WcAcNf = axial design load positive as tensionVf = design shear force for the cross section under the considered conditionMf = total bending moment in the section acting in combination with the shear force VfNf Ac= shall not be taken with a greater numerical value than 04 fcdWc = the section modulus of the concrete cross section with respect to the extreme tension fibre or the fibre

with least compressionIc = the moment of inertia for the un-cracked concrete sectionSc = area moment about the centroid axis of the cross-section for one part of the concrete sectionz1 = the greater of 07 d and Ic Scbw = width of beam web (mm)

203 The capacity for shear force with coinciding axial tension can be taken as the greatest of

and

where

εs = the strain in the most stressed longitudinal reinforcement calculated on the basis of all simultaneousacting load actions where the effect of constraint is included

When calculating Vcd no part of the longitudinal reinforcement in the considered section shall have greaterdesign strain than εsy

204 The capacity for structural members with transverse reinforcement (shear reinforcement) that isdistributed along the longitudinal direction may be assumed equal to the resistance Vcd plus an additional Vsdfrom the transverse reinforcement When calculating Vcd kV shall be set equal to 10 for steel reinforcedmembers

205 The capacity portion Vsd is determined by the force component in the direction of the shear force fromsteel transverse reinforcement crossing an assumed inclined crack at 45 degrees to the longitudinal axis of thestructural member within a depth equal to z from the tension reinforcement

Vsd = Σ (fsd middotASV middotsin α)

For transverse reinforcement consisting of units with spacing s measured along the longitudinal axis thisbecomes

z can be taken equal to 09 d if the cross section has a compressive zone If the entire cross section has tensilestrain z shall be taken equal to the distance h between the utilized longitudinal reinforcement groups (centroid)on the upper and lower side relative to the plane of bending

206 The capacity for compression failure shall be taken as

207 When applying F201 for reinforced concrete members reinforced with FRP reinforcement aslongitudinal tensile reinforcement modifications of kv and kA are required due to the different Youngrsquosmodulus of the FRP reinforcement compared to steel reinforcement as this affects the crack width andaggregate interlock when calculating the contribution from concrete Vco kA shall be taken as

kA = 100 middot EFEsk where kA has units of MPa kv shall be determined through testing

1

25080 zb

A

Nkf

M

VMVV w

c

fvtd

f

fococd sdotsdot

sdotminussdotlesdotsdot+=

051

1 ge

sdotsdot

minus=ctd

fcocd Af

NVV

minus=

sy

scocd VV

εε

1

( ) αα sincot1 sdot+

sdotsdot=

s

zAfV svsd

sd

( ) zbfzbfV wcdwcdccd sdotsdotsdotlt+sdotsdotsdot= 450cot1300 α

208 For concrete members reinforced with FRP bars as shear reinforcement the shear strength of theconcrete section shall be taken as the lower of

mdash Vsd calculated using fFb = ηb times fFd The material factor for strength shall correspond to the duration of theload

mdash Vco + Vsd where Vsd is calculated using fF for a maximum strain The material factor for stiffness shall beused to determine fF

Guidance noteA recommended value for maximum strain is 4permil

mdash For a concrete section with no shear reinforcement (slabs wall etc) the shear capacity shall be taken as Vco

F 300 Truss model method301 The capacity for shear force only or in combination with other action effects can be calculated based onan assumed internal truss model with compressive concrete struts at an angle θ to the longitudinal axis of thebeam The shear reinforcement acts as tension ties and the tensile and the compressive zone as chords in thisassumed truss A capacity portion Vcd in accordance with F200 shall not be included in the capacity302 For members subjected to shear force not in combination with axial compression the angle θ shall bechosen between 25degand 60deg303 For members subjected to shear force with axial compression the angle θ may be chosen less than 25degbut not less than that corresponding to the direction of the principal compression calculated for uncrackedconcrete304 For members subjected to shear force in combination with not negligible axial tension the angle shallnormally be taken as θ = 45deg305 The shear capacity at tensile failure shall be calculated from the force component in the direction of theshear force from the transverse reinforcement ASV crossing an assumed crack at an angle θ to the longitudinalaxis for the structural member within a depth equal to z from the tensile reinforcement

Vsd = Σ fsd middotASV middotsin αwhereα is the angle between the transverse reinforcement and the longitudinal axisθ is the angle between the inclined concrete compression struts and the longitudinal axis306 For transverse reinforcement consisting of units with a spacing s measured along the longitudinal axisthe shear capacity becomes

307 The shear reinforcement for the most unfavourable load case may be designed for the smallest shearforce within a length z middot cot θ corresponding to projection of the inclined crack measured along thelongitudinal axis308 The capacity at compression failure shall be taken as

The design compressive strength fc2d in the compression field shall be determined for the calculated state ofstrain in accordance with Sec6 H When θ is assumed between 30 and 60 degrees the design compressivestrength can be assumed as

309 For reinforced concrete members reinforced with FRP reinforcement as shear reinforcement the fsd inF305 and F306 shall be taken in accordance with the reduced strength formulation for bent FRP shearreinforcement in accordance with F110

F 400 Additional force in the longitudinal reinforcement from shear force401 When calculating according to the simplified method the longitudinal reinforcement shall be designedfor an additional tensile load FSV caused by the shear force

FSV = Vf in structures without shear reinforcementFSV = Vf ndash 05 middotVsd middot(1 + cot α) ge 0 in structures with shear reinforcement

where

( ) ααθ sincotcot +

sdotsdot=

s

zAfV SVsd

sd

( )θ

αθ22 cot1

cotcot

++sdotsdot= zbfV wdcccd

cddc ff 602 =

Vf = Applied design shear forceVsd = Shear carried by shear reinforcement (See F306)

The force FSV shall be assumed to act in both chords if this is unfavourable ie areas near points with zeromoment

402 When calculating according to the truss model method a tensile force Fsv shall be assumed on both sidesof the cross section

FSV = 05 middot Vf middot (cot θ - cot α) ge 0

403 The maximum force in the longitudinal reinforcement on the tension side shall not be taken at greatervalue than the value corresponding to the highest absolute moment in combination with the axial force foundon the same part of the moment curve as the section examined

F 500 Slabs subjected to concentrated actions

501 The design of slabs subjected to concentrated actions causing compression perpendicular to the middleplane of the slab ie column reactions or wheel actions may be carried out in accordance with this sub-sectionThis sub-section is not applicable for cases in which concentrated actions induce tension perpendicular to themiddle plane of the slab as a result for example of a concentrated load and bending moment In these casesa detailed evaluation of the transfer of tension forces shall be performed

502 The calculation can normally be based on a rectangular loaded area with equal area and equal ratiobetween the dimensions in the two main directions as the actual loaded area

503 The capacity at tensile failure for a concentrated action in the inner parts of a slab is determined basedon an assumed governing rectangular section with boundaries at a distance 10 middot d from the loaded area

The governing section shall be chosen in such a way that

mdash an area containing the loaded area is separated by the governing section from the remainder of the slabmdash the governing section at no location is closer to the loaded area than 10 middot dmdash the perimeter of the governing section shall be minimized but straight edges may be assumed ie corners

are not rounded see Figure 7

Figure 7 Cross-section for design check of shear capacity for concentrated load on plates

Figure 8 Cross-section for design check of plates with columns at the corner

d

b

d

a) Inner column b) Column near free edge

x

y

Free edge

b d

bd

1

2

a) Section around column

b

b) Linear section

2

b 1

M y

M x

Free edge

d

b e

B

A

504 For concentrated mobile load near supports the governing action position will be such that the distancefrom the boundary of loaded area to the face of the support is equal to 2 middot d

505 When a concentrated load is applied in the vicinity of a free edge in addition to the section given in F502a governing section shall be assumed extending to the free edge and perpendicular to this see Figure 7

506 Similar rules apply to corners of slabs see Figure 8a In this case the capacity shall also be checked fora section at a distance d from the inner corner of the action The section shall be assumed in the mostunfavourable direction and in such a way that it separates the corner and the action from the remainder of theslab see Figure 8b

507 Where the distance between the outline of an opening in the slab and the outline of the loaded area orcolumn is less than or equal to 5 middot d the portion of the governing section located between two tangents to theoutline of the opening starting from the centre of gravity of the loaded area shall be neglected when calculatingthe shear capacity see Figure 9

Figure 9 Reduction in capacity near opening in plates

508 The distribution of shear forces along the critical section can be calculated in accordance with the theoryfor elastic plates

509 In a simplified approach a linear distribution of shear force along each of the faces of the governingsection is usually assumed A portion of the eccentricity moment caused by a moment introduced from asupporting column an eccentrically located section enclosing a load at a free edge or similar shall be assumedto be balanced by a linear variation of the shear force in the critical section

510 For a rectangular section this portion of the moment can be taken as

Here by is the length of the side of the critical section that is parallel to the moment axis and bx is the sideperpendicular to this For other forms of the governing section the portion of the moment is determined as fora rectangular section with equal area and equal side ratio

511 The portion of the introduced moment that is assumed not to be introduced by a variation of the shearforce shall be transferred by bending moments or torsional moments along the sides of the governing section

512 The capacity Vcd per unit width of the governing section at tensile shear failure for a slab without shearreinforcement shall be determined in accordance with F201

The depth d is taken as the average d = (dx + dy)2 where x and y refer to the reinforcement directions For thereinforcement ratio ρx = Asx (b middot d) and ρy = Asy (b middot d) the geometrical mean for the two directions of tensionreinforcement shall be introduced Asx and Asy are the amount of reinforcement in x- and y-directionrespectively

The reinforcement ratios shall be determined as average values over a width 2 middot d to each side of the loadedarea The capacity shall be reduced in accordance with the regulations in F203 if the slab is subjected to axialtension

The capacity shall be verified for the remaining loading conditions including shear force in plane sectionsoutside the governing section according to F200

513 If the shear capacity of a slab without shear reinforcement calculated in accordance with F501 to F512is less than the calculated action effect shear reinforcement shall be provided in areas where the shear capacityis insufficient

l

d

2

le5dl le l1 2

Opening

Part of section that is notincluded in the calculations

If l lt l an openingwhere l is replaced by l l shall be assumed

1 2

+

x

y

f

b

M

1

yxρρρ =

514 The capacity at tensile shear failure per unit width of the governing section for slabs with shearreinforcement shall be taken equal to the sum of the capacity Vcd calculated using k = 10 plus a contributionfrom the shear reinforcement given by

Vsd shall at least be equal to 075 middot Vcd

515 The required shear reinforcement calculated in the governing section shall be distributed along at leasttwo rows at a distance 05 d to 10 middot d from the face

516 Outside the section 10 d from the face the required shear reinforcement shall be calculated for planesections in accordance with F204 and F205 and be distributed in accordance with F105 The distance betweenthe reinforcement units in the direction perpendicular to the governing section can be up to 075 d in the spandirection

517 The shear reinforcement in the area of concentrated actions may consist of stirrups possibly combinedwith bent bars Other types of steel reinforcement may be added provided the structural performance is verifiedby available documentation

518 Compression failure caused by shear force shall be considered in accordance with F206 for sections atthe face of the loaded area

519 For concrete members reinforced with FRP bars as longitudinal tensile reinforcement the provision ofF512 and F514 shall be supplemented by the requirements in F207 and F208 for the prediction of the shearstrength Vcd

G Torsional Moments in Beams

G 100 General

101 The capacity for torsional moment shall be checked for tensile and compression failure

If the load transfer in the ultimate limit state is not dependent on the torsional capacity the design can normallybe performed without considering torsional moments

102 The torsional capacity of the cross section shall be calculated based on an assumed closed hollow sectionwith an outer boundary coinciding with the actual perimeter of the cross section The wall thickness of theeffective cross section shall be determined as the required thickness using a design compressive concrete stresslimited to fc2d where fc2d equals the reduced design compression strength under biaxial tensile stressHowever for pure torsion the assumed wall thickness shall be limited to 02 multiplied by the diameter of thelargest circle which can be drawn within the cross-section and maximum equal to the actual wall thickness forreal hollow sections Concrete outside the outer stirrup shall not be included in the design if the distance fromthe centre line of the stirrup to the face of the concrete exceeds half of the assumed wall thickness or if the totalinclined compressive stress from torsional moment and shear force exceeds 04 middot fcd The concrete outside thestirrups shall always be neglected if the concrete surface is convex

103 The individual cross-sectional parts can be designed for the calculated shear forces in accordance withthe general method in H or in accordance with the requirements of G104 to G107

104 Internal forces shall be determined in accordance with recognized methods based on the equilibriumrequirements under the assumption that the concrete cannot carry tension Where tensile strain occurs in theconcrete the forces shall be calculated as for a space truss model at the middle surface of the assumed wallsIn this truss all tensions shall be transferred by reinforcement while the concrete can transfer compression

105 Compressive failure limits the torsional capacity of the cross section

The capacity at compressive failure for only torsional moment is the value giving a compressive concrete stressequal to fc2d according to H106 and H107 The compressive stress is calculated for the assumed hollow sectionfor the same equilibrium state as the one used to design the governing torsional reinforcement

For torsional moment in combination with shear force or axial force the capacity for compressive failure shallbe determined by taking the maximum compressive concrete stress in the effective cross section as fc2d

106 The capacity at tensile failure shall be determined by the maximum tensile forces that the torsionalreinforcement can transfer in the assumed spacial truss The design may be based on a consideration of shearwalls It shall be demonstrated that the corresponding internal forces in the corners can be transferred

107 For torsional moment in combination with bending moment axial force or shear force the requiredreinforcement may be calculated as the sum of required reinforcement due to torsional moment and due to theother action effects

αsinSVsdsd AfV =

108 Torsional reinforcement shall be provided as closed stirrups with proper anchorage In structures orstructural members which according to these regulations shall be designed for torsion this stirrupreinforcement in each face shall have a minimum cross section of

where Ac is the concrete area of a longitudinal section calculated using the minimum wall thickness of a hollowsection or 02 multiplied by the diameter of an enclosed circle in accordance with G102 and G103 for a solidcross section The tensile strength ftk shall not be entered with a lesser value than 255 MPa

109 If the load transfer is totally dependent on the torsional capacity the spacing between the stirrups shallnot exceed 300 mm If in addition the design torsional moment exceeds half of the capacity of the cross sectioncalculated at compressive failure the link spacing shall be less than 300 mm and at fully utilized concretesection not exceed 150 mm

110 In addition to stirrup reinforcement the torsional reinforcement shall consist of a longitudinalreinforcement either nearly uniformly distributed or concentrated in the corners The spacing shall not exceedthat given for stirrups and the longitudinal reinforcement shall have a cross-sectional area per unit length alongthe perimeter of the stirrup at least equal to the minimum area required per unit length for stirrups

111 The longitudinal reinforcement may be less than this provided axial compression is actingsimultaneously or the stirrup reinforcement is placed nearby parallel to the principal tensile stress directionand provided that the capacity is sufficient At least one bar shall be provided in each corner of the stirrups andhaving at least the same diameter as the stirrups

112 Torsional reinforcement both stirrups and longitudinal reinforcement shall be distributed in the crosssection in such a way that all cross-sectional parts get at least the required minimum reinforcement

113 For reinforced concrete members reinforced with FRP bars as torsional reinforcement the provision ofG106 and G107 shall be supplemented by limiting the tensile strain in the torsional reinforcement

Guidance noteA recommended value for maximum strain to be utilized is 4permil

114 For reinforced concrete members reinforced with FRP reinforcement as torsional reinforcement Theminimum torsion reinforcement provided by G108 shall modified by replacing fsk with the tensile stress of theFRP reinforcement corresponding to a maximum strain

Guidance noteA recommended value for maximum strain to be utilized is 4permil The corresponding tensile strength is fsk = EF times 4permil

H General Design Method for Structural Members Subjected to In-plane Forces

H 100 General

101 Design for forces acting in the middle plane of a structural member may be performed by a method basedon an assumed internal force model satisfying equilibrium conditions and compatibility requirements for thelocal region to be designed

102 The concrete is assumed to transfer compression by compression fields and the reinforcement in two ormore directions transfers tension Under certain conditions a limited transfer of shear forces parallel to thecracks and tension in concrete between the cracks may be assumed

103 Strains and stresses shall be calculated as average values over a cracked region The strains can beassumed constant in local regions and through the thickness Average strain in the reinforcement can beassumed equal to the average strain parallel to the direction of reinforcement for the region Principal stress andprincipal strain of the concrete are assumed to have the same direction in the assumed compression field

104 Design of shear walls plates and shells can be based on forces acting in the plane When members aresubjected to moments in combination with membrane forces the design may be performed by assuming thestructural member divided into layers where the action effects are taken as membrane forces uniformlydistributed through the thickness in each layer and where the average strain in the layers satisfies the conditionof linear strain variation through the thickness

105 This method of calculation may also be used when designing for shear force in beams and slabs withshear reinforcement and for torsional moment in beams

106 The design basis shall provide a relation between stress and strain for both reinforcement and concretein areas subjected to a biaxial stress state in cracked concrete that is documented to give agreement between

sk

tkc f

fA250

calculated capacity and tests For steel reinforcement the relation between average strain and average stressgiven in C303 can be assumed For FRP reinforcement the stress strain relation is given in C401107 For concrete subjected to compression the relationship between strain and stress given in C114 with thestress ordinate reduced by the factor fc2d fcd may be assumedFor concrete in the assumed compression field a reduced design compressive strength shall be taken as

where ε1 is the average principal tensile strain108 The average tensile stresses between cracks shall be determined by relationships documented byrepresentative tests109 It shall be demonstrated that the cracks can transfer both the shear stresses in the concrete and the tensilestresses in the reinforcement which are derived from the equilibrium requirements110 If the concrete tensile stresses between the cracks are not considered (σ1 = 0) the check of the stresscondition in the cracks can be waived111 The stresses in the steel reinforcement at the cracks shall be determined from the equilibrium conditionsand shall not exceed the design strength of the steel reinforcement For FRP reinforcement stresses shall notexceed a design stress corresponding to a maximum strain The design strength shall be calculated consideringa material factor related to the duration of the loading according to C108

112 For concrete members reinforced with FRP bars as longitudinal and transverse reinforcement theprovision of H106 shall be modified by referring to the appropriate stress-strain curve for FRP in C401

H 200 Membrane (in-plane) shear resistance201 Resistance to membrane forces in plates and shells shall be determined by recognized methods based onequilibrium considerations The tensile strength of concrete shall be neglected 202 For membrane forces only ie when the slab element is subjected to in-plane forces only (Figure 10) andthe reinforcement is disposed symmetrically about mid-depth the element may be designed as outlined belowwhen at least one principal membrane force is tensile The concrete is considered to carry compressive stress(σc) at angle θ to the x-axis (in the sense corresponding to the sign of Nxy)The two sets of reinforcing bars are designed to carry the forces Fx and Fy where

Fx = Nx + Nxymiddot cot θFy = Ny + Nxymiddot tan θ

(the units for F are in forceunit length) valid for positive values of Fx and Fy and taking tensile stresses aspositiveThe angle θ may be chosen arbitrarily for each loading case and each slab element paying due regard to therequirements of Q concerning minimum reinforcementFor Nx lt - |Nxy|middot cot θ no reinforcement is required in the x-direction Fy and σc are then given by

cdcd

dc ff

f lesdot+

=1

2 10080 ε

θθσ

cossin sdotsdot=

b

Nxy

c

x

xyyy N

NNF

2

minus=

h

N

NN

x

xyx

c

2

+=σ

For Ny lt - |Nxy| tan θ no reinforcement is required in the y-direction Fx and σc are then given by

Finally a situation may occur where both Nx and Ny are negative and Nx middot Ny gt Nxy2 No reinforcement is

required and principal membrane forces may be calculated in accordance with conventional formulae

Figure 10 Slab element subjected to membrane forces

203 Membrane forces and bending moments combinedIn cases where a slab element is subjected to combinations of moments and membrane forces or to momentsonly the slab element may be regarded as a sandwich consisting of two outer layers and a central zone Theapplied forces and moments may be resolved into statically equivalent ldquomembranerdquo forces on the outer layersas shown in Figure 11 Each layer is then designed in accordance with the general principles given forldquoMembrane forces onlyrdquo

Figure 11 Applied forces and moments resolved into membrane forces in sandwich layers

y

xyxx N

NNF

2

minus=

h

N

NN

y

xyy

c

2

+=σ

y

xxN

xyN

1

θ

Ax

Ay

xN

yN

2

s c

z

yx

Nx+

x0N

Nx-

+yN

Ny0

N -y

a) Normal Force

+xyN

b) Shear Force

yx

z

xy0N

Nxy-

yx-

yx

yx+N

N

+xN

a) Bending Moment

N -x

yx

z

N +

y-N

y

b) Torsion Moment

xy-

xy+N

N

x y

z

N +yx

Mx

yM -Nyx

yxMMxy

I Regions with Discontinuity in Geometry or Loads

I 100 General101 In areas with discontinuities in geometry or loads such that assumptions of plane sections remainingplane are invalid the calculation may be based on force models in sufficient conformity with test results andtheoretical considerations The models might be truss systems stress fields or similar that satisfies theequilibrium conditionsIf there is no recognized calculation model for the member in question the geometry of the model may be determinedfrom the stress condition for a homogeneous un-cracked structure in accordance with the theory of elasticity102 The provisions of this sub-section shall be used to determine internal forces in the member at a distanceless than d from the support or from concentrated loads The internal forces may be used at distances up to 2 middot d103 Internal forces shall be calculated based on an assumed force model of concrete compression struts andties of reinforcement Effective cross section for concrete compression struts shall be assumed in accordancewith recognized calculation models104 Tensile forces caused by possible deviation in the assumed compressive field shall be consideredThe reinforcement shall be shaped in accordance with the analytical model and be anchored in accordance withthe provisions of K at the assumed joints105 Calculated concrete stresses in struts shall not exceed fc2d as given in H107 When calculating fc2d theaverage principal tensile strain is derived from the principal compressive strain in the strut and the tensile strainin the reinforcement crossing the strut106 It shall be demonstrated that the calculated forces in the assumed struts and ties can be transferred in thejoints with design concrete compressive strength in accordance with I105 and the other provisions of thisstandard Increased design concrete compressive strength may be taken into account for partially loaded areasWhere there is no special reinforcement or compressive stress normal to the compressive struts in the forcemodel reduced compressive concrete strength shall be assumed107 If the reduced compressive concrete strength fc2d is not derived from the strain condition the calculatedcompressive concrete stress in the assumed joints shall not exceed the following values

11 middot fcd in joints where no tensile reinforcement is anchored (bi- or triaxial compression)09 middot fcd in joints where tensile reinforcement in only one direction is anchored07 middot fcd in joints where tensile reinforcement in more than one direction is anchored

108 When applying the truss analogy in area with discontinuity in geometry the maximum stress in the FRPbars shall not exceed the design strength specified in F110 for the appropriate load combination as specified inSec5 D100

J Shear Forces in Construction Joints

J 100 General101 In concrete joints between hardened concrete and concrete cast against it the transfer of shear forces canbe assumed in accordance with the provisions given in this sub-section102 Construction joints shall not be assumed to transfer larger forces than if the structure was monolithicallycast103 A hardened concrete surface is classified as smooth rough or toothed A surface may be assumed asrough if it has continuously spread cavities of depth no less than 2 mm When surfaces are assumed as toothedthe toothing shall have a length parallel with the direction of the force not exceeding 8 times the depth and theside surfaces of the toothing shall make an angle with the direction of the joint no less than 60deg The minimumdepth shall be 10 mm104 The design shear strength of concrete τcd can be taken into account only for contact surfaces that arecleaned and free of laitance before concreting and where there are no tensile stresses perpendicular to thecontact surface105 The shear force capacity parallel to a construction joint with an effective area Ac and reinforcement areaAs through the joint surface shall be taken as

Vd = τcd middot Ac + fsd middot As (cos α + μ middot sin α) - μ middotσc middot Ac lt 03 middot fcd middot Ac

where

AS = the reinforcement area that is sufficiently anchored on both sides of the joint and that is not utilised forother purposes

α = the angle between the reinforcement and the contact surface where only reinforcement with an anglebetween 90deg and 45deg (to the direction of the force) shall be taken into account

μ = the friction factorσc = the smallest simultaneously acting concrete stress perpendicular to the contact surface

106 The reinforcement crossing the joint shall have a total cross-sectional area no less than 0001 Ac or thereshall be a simultaneously acting compressive normal stress of minimum 04 MPa

107 In joints parallel to the longitudinal axis the distance between the reinforcement units shall not exceed 4times the minimum concrete thickness measured perpendicular to the contact surface or 500 mm

The combination of values given in Table J1 that gives the minimum capacity shall be used in the design

108 When the contact surfaces are toothed the design shear strength τcd shall be assumed to act on a cross-section giving the smallest net area at the base of the toothing

109 The design strength τcd in the contact surface shall be determined for the concrete part having the loweststrength

110 Reinforcement may be omitted in rough or toothed construction joints transferring shear forces in thefollowing cases

mdash Where the parts are sufficiently secured against moving from each other perpendicular to surfaces by othermeans The capacity shall be calculated in accordance with J105 to J109

mdash In structures with uniformly distributed dominantly static live load not exceeding 5 kPa and minor failureconsequences The design bond strength of the concrete shall be taken as 05 middot τcd and the forces in theconcrete joint shall be determined in accordance with the method described for composite structures inA500

mdash In structures where the composite action between the parts is not accounted for when calculating thecapacity it shall be verified that this has no detrimental effects in the serviceability limit state

111 When calculating capacity for transfer of shear forces in concreted joints between precast members theprovisions in J105 to J109 may be waived provided there is sufficient basis to assuming other values than givenin Table J1

112 For concrete members reinforced with FRP reinforcement as longitudinal reinforcement crossing aconstruction joint the provisions in J105 shall be modified by replacing fsd with the design stress of the FRPreinforcement corresponding to a maximum strain The design strength shall be calculated considering amaterial factor related to the duration of the loading according to C108

113 For concrete members with FRP bars as reinforcement crossing a construction joint the minimumamount of reinforcement required in accordance with the provisions in J106 shall be modified with thefollowing factor 200EF with EF in MPa when the alternative compressive stress criteria is not satisfied

K Bond Strength and Anchorage Failure

K 100 General

101 The distances between the reinforcement bars shall be such as to ensure good bond

102 Reinforcement in different layers shall be aligned in planes leaving sufficient space to allow for thepassage of an internal vibrator

103 Lap joints shall be made in a way that secures transfer of force from one rebar to another The reductionof strength of a lap joint due to closely spaced lap joints shall be taken into account where relevant

104 The lap joints shall be distributed The maximum number of lap joints occurring at a given cross sectionalplane is normally limited by the smaller of

mdash 12 of the reinforcement area

Table J1 Values for force transfer in construction joints

Contact surface

ΣAs gt 0001 Asor σc lt - 04 MPa

Combination 1 Combination 2τcd μ τcd μ

Smooth 0 070 0 07Rough 0 150 06ftd 08Toothed 0 180 15 ftd 08

mdash one reinforcement layer (the layer with largest reinforcement area)

105 Resistance against bond and anchorage failure shall be determined by recognized methods Both localbond and anchorage bond shall be investigated

In zones of reduced bond (eg where gravitational settling of the concrete may reduce the compaction aroundthe reinforcement) the design bond strength shall not be taken higher than 70 of the value for good bondzones

Consideration shall be given to the state of stress in the anchorage zone Adequate bond resistance shall beassured by transverse reinforcement stirrups spirals hooks or mechanical anchorages

106 Individual reinforcement bars shall have a development length no less than

where

φ = the diameter of the reinforcement barσs = the calculated stress in the reinforcement bar in ultimate limit state at the cross section in questionfbd = the design bond strength calculated in accordance with K116t = the specified longitudinal tolerance for the position of the bar end If such tolerances are not specified

on the drawings the value of t shall not be taken less than 3φ

107 Required lap length when splicing shall be taken equal to the calculated development length Therequired lap length shall be not less than the greater of 20 φ and 300 mm The development length shall not beassumed to be effective over a length exceeding 80 φ108 Bundled reinforcement bars shall have a development length no less than

where

φe = equivalent diameter in term of reinforcement cross sectionfbc = design bond strengths in accordance with K116 with φ = φefbs = design bond strengths in accordance with K116 with φ = φekn = factor dependent on the number of bars in the bundle and is taken as

08 for bundle of 2 bars07 for bundle of 3 bars06 for bundle of 4 bars

t = the specified longitudinal tolerance for the position of the bar end see K106

The development length shall not be assumed to be effective over a length exceeding 80 φe

For lapped splices of bundled reinforcement with equivalent diameter larger than 32 mm the bars shall belapped individually and staggered at least the development length lb When terminated between supports thebars shall be terminated individually and staggered in the same way The development length shall becalculated for each individual bar by entering the diameter of the bar in question for φc in the formula

109 The development length for steel welded wire fabric shall be no less than

where

ΣFvn γs = sum of forces Fvn corresponding to shear failure at cross wire welds within the development lengthlb = development length in accordance with K106lrsquob = shall not be taken as larger than the development length in accordance with K125fbd = design bond strength calculated in accordance with K116 see also K106

For welded wire fabric Fvn = 02 middot As middot fsk ge 4 kN where As is the sectional area of the largest wire diameter

Required lap length is equal to the calculated development length The lap length shall not be less than thelargest of 20 middotφ and 200 mm

110 For individual prestressed reinforcement units the development length for the prestressing force shall betaken as

lbp = α middotφ + β middot σpmiddotφ fbc

where

tf

lbd

sb +sdotsdot= σφ250

tffk

lbsbcn

seb +

+sdotsdotsdot= σφ250

sdotsdotsdotminus=

bds

vnbb f

Fll

φγ30

α is a factor given in Table K1

β is a factor given in Table K1

φ is the nominal diameter of the reinforcement unit

σp is the reinforcement stress due to prestressing

fbc is the concrete related portion of the design bond strength in accordance with K116

The part α φ in the formula for lbp defines a length where no force transmission is assumed

111 Post tensioning anchorages shall be designed for the design strength of the tendon The anchorage unitshall be designed so that transfer of forces to the surrounding concrete is possible without damage to theconcrete Documentation verifying the adequacy of the anchorage unit shall be approved

112 The design of anchorage zones shall be in accordance with recognized methods Reinforcement shall beprovided where required to prevent bursting or splitting The design strength of such reinforcement should belimited in order to control cracking due to the applied force

mdash to 300 MPa in case of steel reinforcementmdash to the stress corresponding to a strain of 2permil in case of FRP reinforcement In order to assess the stress

corresponding to this strain EFd shall be used

113 The release of prestressing force may be assumed to be smooth if one of the following requirements isfulfilled

mdash The prestressing force is released gradually from the abutmentsmdash The impact against the end of the concrete structure is damped by a buffer between the end of the concrete

structure and the point where the reinforcement is cutmdash Both concrete and prestressed reinforcement are cut in the same operation by sawing

114 Development of tensile force caused by external loads shall be calculated in accordance with K106Within the development length for prestressed tensile force fbd shall be reduced by the factor (1 - σp fbc) Inthis calculation long-term reduction of σp caused by shrinkage creep and relaxation shall be considered Thedevelopment length for the reduced prestressing force shall be assumed to be unchanged equal to lbp

Figure 12 Prestressed force introduction length where prestressed force is anchored in bond

115 Transverse tensile forces in the development zone shall be resisted by reinforcement unless it is shownthat reinforcement can be omitted

Table K1 Coefficients to be used when calculating development length for prestressed reinforcement units

Type ofreinforcement

Smooth release of prestressing tension force

Sudden release ofprestressed tension force

α β α βPlain wire 10 020 - -Indented wire 0 017 10 021Strand 0 014 5 017Ribbed bar 0 007 0 008FRP To be provided in FRP Material Certificate

σφ

f s

σp

As

σs As

l

Force caused by external load

Prestressing force

bp

b

End ofreinforcement unit

116 The design bond strength fbd for ribbed bar indented bar indented wire and strand can be taken as

where

k1 = factor depending of the type of reinforcement given in Table K2c = the least of the dimensions c1 c2 and (s1 - φ)2 given in Figure 13φ = the diameter of the anchored reinforcementk3 = factor dependent on the transverse reinforcement and its position as given in Figure 14

The factor k3 is taken as zero for strandsAst = the area of transverse reinforcement not utilized for other tensile forces and having a spacing not greater

than 12 times the diameter of the anchored reinforcement If the reinforcement is partly utilized the areashall be proportionally reduced

s1 = the spacing of the transverse reinforcementk2 = has the value 16 if the spacing s between the anchored bars exceeds 9 φ or (6 c + φ) whichever is the

larger k2 has the value 10 if s is less than the larger of 5φ and (3c + φ)For intermediate values interpolate linearly

117 For plain reinforcement take

a) Distance for anchorage b) Distance for splicesFigure 13 Values of concrete cover and bar spacing for calculation of bond strength

Figure 14 Values of k3 for various types of transverse reinforcement for calculation of bond strength

Table K2 Values of k1 for various types of Reinforcement

Type of Reinforcement k1Ribbed bar 14Intented bar and wire 12Strand 12Plain bar 09Plain wire in welded wire fabric and prestressed reinforcement

05

FRP To be provided in FRP Material Certificate

tdbsbcbd fkfff sdotsdotle+= 12

sdotsdot+sdotsdot= φ

32

3

121

cfkkf tdbc

MPas

Akf st

bs 511

3 le

sdot

=φ

tdbd fkf sdot= 1

C

C S2

1

Sll

(Section in way of rebar overlap)

a) b)

k = 40 Nmm32 k = 20 Nmm3

2 k = 03

118 When calculating development of force in reinforcement which during concreting has an angle less than20deg to the horizontal plane the following reduction of the portion fbc of the design bond strength fbd accordingto K116 shall be made

mdash If the concreting depth below the reinforcement exceeds 250 mm the reduction for ribbed bars is 30 andfor other types of bars 50 If the concreting depth is 100 mm or less no reduction is made Forintermediate values linear interpolation shall be performed

mdash If there is a tensile stress perpendicular to the anchored reinforcement larger than 05 ftd in the developmentzone the reduction is 20

The highest of the reductions given above shall be applied The reductions shall not be combined119 At a simply supported end the development length determined according to K106 to K115 may bereduced above the support if the support reaction is applied as direct compression against the tension face Inthis case the stirrups shall continue throughout the support regionWhen calculating the development length the value fbc may be increased by 50 but fbd shall not have ahigher value than what corresponds to the maximum value in accordance with K116120 Reinforcement that is taken into account at the theoretical support shall normally be extended at least100 mm beyond this The position of the reinforcement shall be given on the drawings with tolerance limits121 If reinforcement in several layers are spliced or anchored in the same section the capacity shall belimited to the value that can be calculated for the bars in only one layer using the layer that gives the highestcapacity This provision may be waived if otherwise demonstrated by a more accurate design122 Reinforcement can also be anchored with special anchor units such as end plates A combination ofseveral anchorage methods may be utilized The total anchorage capacity can be calculated as the entire capacityfrom the anchorage method giving the highest portion and half of the anchorage capacity from each of theremaining anchorage methods For plain steel a combination of bond and end anchorage shall not be utilized123 For steel tensile reinforcement of ribbed bar or indented bar with an anchorage hook a concentrated forcedevelopment along the bent part of the hook may be assumed A hook shall only be assumed effective if it hastransverse reinforcement and is formed in accordance with Q408 If the hook is bent with an angle of 90deg thestraight end after the bend shall be at least ten times the diameter of the bent bar If the angle is 135deg the straightpart may be reduced to five times the diameter of the barFor bars of steel compliant with EN 10080 (see Q400) the concentrated force in the bend may be taken as 25of the capacity of the bar if the hook has an angle of 90deg If the angle is 135deg the force can be taken as 40 Anchorage for the remaining portion of the force in the bar shall be calculated by force development along thebar outside the bent partTensile reinforcement compliant with EN 10080 with anchorage hook as described above may be presumedto be anchored in the bent part of the bar provided the bar is bent with a mandrel of diameter equal to or lessthan 4 middot φ and otherwise bent in accordance with Q400124 For FRP reinforcement the capacity of the reinforcement in the bend shall be calculated in accordancewith F110125 If the development length of steel reinforcement is not calculated in accordance with K106 to K108 theanchorage length of reinforcement in one layer in normal density concrete may simplified be determined asfollows

a) For ribbed bars of steel compliant with EN 10080 the anchorage length shall be taken as 50 middot φ This appliesprovided the concrete cover is at least φ and the spacing between the anchored bars is at least 8 middot φ Iftransverse reinforcement is located closest to the concrete surface and the concrete cover of the anchoredreinforcement is at least 15 middot φ the spacing shall be at least 5 middot φ

b) For plain bars with end hooks the anchorage length is taken as 40 middot φ assuming that fsk le 250 MPac) For welded wire fabric the anchorage length shall be at least so large that

mdash 3 transverse bars are located in the anchorage zone for welded wire fabric of bars with diameters from4 to 9 mm

In addition the anchorage length shall be no less than

mdash 30 middot φ for mesh made of indented bars mdash 40 middot φ for mesh made of plain bars

The development of the force along the anchorage length may be assumed uniformFor reinforcement which has a concrete depth below the reinforcement larger than 150 mm or an angle lessthan 20deg to the horizontal plane the anchorage length shall be increased by 10φ for ribbed bars and welded wirefabric of indented bars and 20 middot φ for plain bars

126 These provisions are not applicable to FRP bars The required minimum reinforcement in accordancewith Q shall be spliced for its full capacity

127 Along the development length a transverse reinforcement or stirrups shall be provided in accordancewith Q303 unless a more accurate assessment is made If this reinforcement is provided with FRP rods it shallbe designed considering a stress corresponding to a strain of 4permil In order to assess the stress corresponding tothis strain EFd shall be used

L Partially Loaded Areas

L 100 General

101 Where a compression force Ff is transferred to a concrete member with nearly uniformly distributedcompressive stresses over a limited loading area A1 increased compressive stress over the loaded area relativeto fcd may be allowed provided this area represents only a part of the surface (cross section) of the concretemember and if the force can be assumed transferred further in the same direction and distributed over a largerdistribution area A2 in the concrete member This provision is applicable for design in ULS For fatigue lifeprediction any increase in strength shall be documented

102 The loaded area A1 used in the calculation and the assumed distribution area A2 shall be such that theircentroids coincide with the applied force resultant The side faces of the cut pyramid or cone which are formedbetween loaded area and distribution area shall not have an inclination larger than 12

103 The cross-sectional dimensions of the distribution area shall not be assumed larger than the sum of thedimensions of the loaded surface measured in the same main direction and the concrete thickness measuredparallel to the direction of the force

104 If more than one load acts simultaneously the respective distribution areas shall not overlap each other

105 The compressive capacity for normal density concrete can be taken as

106 The compressive capacity for lightweight concrete can be taken as

107 The dimensions of the distribution area shall not be assumed greater than 4 times the dimensions of theloaded area measured in the same main direction see Figure 15

Figure 15 Geometrical limitations for partial loaded areas

3

1

21 A

AfAF cdcd sdot=

4

1

21 A

AfAF cdcd sdot=

cα

Ff

1A

A2

tg a lt frac12 a lt a + c2 1 tg a lt frac12 a lt a + c a b = a b lt 2

α

2 1

A2

fF

A1

c

2 21 1

a

lt 15a lt 15a 11

2

1

b b

1 2A1

A2 lt 4

bb

lt 15a

2A

A

lt 15a

a

1

1 1

2

1

108 If the ratio between the larger and smaller dimension of the loaded area is less than 2 and the distributionarea A2 is assumed to be geometrically identical to the loaded area A1 the compressive capacity for normaldensity concrete may be taken as

The compressive capacity for lightweight aggregate concrete may be taken as

see Figure 15

109 Provisions in L105 to L108 are applicable for design in ULS Fatigue life shall be predicted based on fcdunless increased strength under fatigue loading is properly documented

110 The concrete shall be sufficiently reinforced for transverse tensile forces

In the two principal directions perpendicular to the direction of the compressive force reinforcement for thetransverse forces shall be provided according to

025 middot Ff (1 ndash a1a2) and 025 middot Ff (1 ndash b1b2)

see Figure 15

The transverse tensile reinforcement shall be placed such that the centroid of the reinforcement is located at adistance from the loaded area equal to half the length of the side of the distribution area in the same directionbut not larger than the distance to the distribution area The reinforcement may be distributed over a widthcorresponding to the length of the side of the distribution area normal to the direction of the reinforcement andover a height that corresponds to half the side of the distribution area parallel to the direction of thereinforcement

Additional reinforcement shall be provided if additional transverse forces can develop caused by transverseexpansion of soft supports (shims) fluid pressure or similar

111 In case the transverse tensile reinforcement provision specified in L110 is met with FRP bars the bars shallbe designed for a tensile stress corresponding to a maximum strain If bends are provided in the transverse tensilereinforcement the design strength shall not exceed the bend capacity calculated according to F110 In both casesthe material factor corresponding to the duration of the loading according to C108 shall be considered

Guidance note

A recommended value for maximum strain to be utilized is 4permil

112 It shall be demonstrated that forces caused by bent reinforcement can be resisted If no reinforcement isprovided for transverse tension normal to the plane of the bent reinforcement the reinforcement shall not bebent around a mandrel diameter less than determined by the equation

where β is the opening angle of the bend

Here is s the spacing of the reinforcement bars For reinforcement near the free surface parallel to the plane ofthe bent reinforcement the spacing s shall not be greater than twice the distance from the centre of the bar tothe free surface

If it is necessary to provide reinforcement for transverse tension the total area of this reinforcement shall be atleast 40 of the area of the bent bar The transverse reinforcement shall consist of at least 2 bars placed withinthe curve of the bend Transverse reinforcement may be omitted provided there are compressive stresses at leastequal to ftd normal to the plane of the bent bar

In order to limit the contact pressure in the bend the reinforcement shall not be bent around a mandrel diameterless than determined by the equations

cdcdcd fAA

AfAF sdotsdotlesdot= 1

1

21 3

cdcdcd fAA

1

21 2

minus

sdotsdotsdot=

2cos1

40 2 βφσφsfs

Dtd

s

cd

s

fsD

σφφ= for normal density concrete

and

In this calculation s shall not exceed 4 middot φ

For requirements to the mandrel diameter see also Q400

It is not necessary to check that stirrups made in accordance with Q408 are in accordance with the provisionsof this clause This paragraph is not applicable for FRP bars

M Fatigue Limit State

M 100 General

101 The entire stress history imposed during the life of the structure that is significant with respect to safeservice life evaluation shall be taken into account when determining the long term distribution of stress cycles(see Sec5 E2000)

102 The random nature of the loads shall be accounted for in determination of the long term distribution ofstresses Both the variation of stress ranges and mean stresses and durations shall be considered The methodof analysis shall be documented

103 The effects of significant dynamic response shall be properly accounted for when determining stressranges Special care shall be taken to adequately determine the stress ranges in structures or members excitedin the resonance range The amount of damping assumed shall be appropriate to the design

104 The geometrical layout of the structural elements and reinforcement shall be such as to minimize thepossibility of fatigue failure

105 Fatigue design may alternatively be undertaken utilizing methods based on fatigue tests and cumulativedamage analysis methods based on fracture mechanics or a combination of these Such methods shall beappropriate and adequately documented

106 For structures subject to multiple stress cycles it shall be demonstrated that the structure will endure theexpected stresses during the required design life

107 Calculation of design life at varying stress amplitudes andor mean stress can be based on cumulativelinear damage theory The stresses due to cyclic actions may be arranged in stress blocks Each stress block canbe defined by the peak stress and trough stress and a corresponding number of stress cycles A minimum of 10blocks is recommended for each stress level even distributed so that each block provides a significantcontribution to the total damage ratio

108 If the random nature of the loads implies that the stress ranges mean stress and durations vary a lineardamage accumulation law may be assumed

109 where k is the number of stress blocks used (ge10) per load ratio ni is the number of cycles in stress blocki Ni is the number of uniform cycles with the same mean stress range and duration which causes failure

110 The characteristic fatigue strength or resistance (S-N curve) of a structural detail shall be applicable forthe material structural detail state of stress considered and the surrounding environment S-N curves shall takeinto account any relevant material thickness effects Such S-N curves shall be documented Alternatively S-Ncurves for concrete steel and FRP may be used together with the stresses obtained from analysis provided thatthese are calculated based on criteria outlined in Sec5 E

111 Fatigue strength relationships (S-N curves) for concrete shall take into account all relevant parameterssuch as

mdash concrete qualitymdash predominant load effect (axial flexural shear bond or appropriate combinations of these)mdash state of stress (cycling in pure compression or compressiontension)mdash surrounding environment (air wet submerged)

cd

s

fsD

σφφ51= for lightweight aggregate concrete

ηle==

k

i i

iN

nD1

112 The limit for the cumulative damage ratio (η) to be used in the design shall depend on the access forinspection and repair Limits for cumulative damage ratios according to Table M1 are normally acceptable forconcrete and steel reinforcement

113 The action effects shall be calculated according to the theory of elasticity114 The capacity may be assumed to be adequate when calculated design life for the largest acting amplitudecorresponds to at least 20 times 106 cycles if the fatigue loading is caused by randomly variable actions such aswind waves traffic etc115 For FRP reinforced concrete structure with a uniform load history (constant mean and stress range) thelimit for the damage ratio (η = nN) to be used in design is 033 116 For FRP reinforced concrete structures with a non-uniform load history if this cumulative damagetheory is used the damage ratio (η) to be used in design is 003The permitted cumulative damage ratio due toexposure to variable loading is specified to account for uncertainty in the damage accumulation model anddegradation of residual strength towards the end of the lifetime

M 200 Fatigue strength design life

Concrete and grout201 The design life of concrete and grout subjected to cyclic stresses may be calculated from

where

frd = the compression strength for the type of failure in questionσmax = the numerically largest compressive stress calculated as the average value within each stress-blockσmin = the numerically least compressive stress calculated as the average value within each stress-blockC5 = fatigue strength parameter For concrete C5 shall be taken equal to 10 For grout C5 shall be

determined by testingGuidance noteIn the absence of fatigue tests for grout C5 may be taken as 08

When σmin is tension it shall be taken as zero when calculating the design lifeThe factor Cl shall be taken as

120 for structures in air100 for structures in water for those stress-blocks having stress variation in the compression-compression range80 for structures in water for those stress-blocks having stress variation in the compression-tension range

If the calculated design life log N is larger than the value of X given by the expression

The design life may be increased further by multiplying the value of log N by the factor C2 where this is taken asC2 = (1 + 02 (log10 N - X)) gt 10

Steel reinforcement202 The design life of reinforcement subjected to cyclic stresses may be calculated based on

log10N = C3 ndash C4 log10Δσ

Table M1 Limit of cumulative damage ratios (η)No access for

inspection and repairBelow or in the splash zone1) Above splash zone 2)

033 05 101) In typical harsh environment (e g the North Sea or equivalent) structural details exposed to seawater in

the splash zone are normally to be considered to have no access for inspection and repair ie the limit for the cumulative damage ratios shall be reduced to 033

2) For reinforcement which cannot be inspected and repaired the limit for the cumulative damage ratio for reinforcement above splash zone is reduced to 05

sdot

minus

sdot

minus=

rd

fC

fCCN

5

min

5

max

110

1

logσ

σ

15

min

1

101 CfC

CX

rd

sdot+sdot

minus= σ

whereΔσ is the stress variation of the reinforcement (MPa)C3 and C4 are factors dependent on the reinforcement type bending radius and corrosive environmentThe maximum stress σmax in the reinforcement shall be less than fskγs where γs is taken from Table C1203 For straight reinforcement bars in a concrete structure under exposure classes X0 XC1 XC2 XC3 XC4XF1 XA1 and XA2 the value of C3 = 196 and C4 = 60 shall be used See O200 for exposure class definitionsFor reinforcement bent around a mantel of diameter less than 3 middot φ and used in a structure under exposure classX0 XC1 XC2 XC3 XC4 XF1 XA1 and XA2 the value of C3 = 159 and C4 = 48 shall be used See O200for exposure class definitionsFor intermediate bending diameters between 3 middot φ and straight bars interpolated values may be usedInfinite fatigue life may be assumed if the calculated value of N is greater than 2 middot 108 cycles204 Values of C3 and C4 for straight bars in a concrete structure under exposure class XD1 XD2 XD3 XS1XS2 XS3 XF2 XF3 XF4 XA3 and XSA are suggested in Table M2 For straight reinforcement bars in aconcrete structure exposed to specially or severely aggressive environment which are not included in theprevious list the influence of corrosion on the fatigue properties shall be assessed separately See O200 forexposure class definitions Special assessment shall also be made for bent barsReinforcement which is protected against corrosion using cathodic protection may be assessed for fatigue lifeusing the values C3 and C4 in M203

FRP reinforcement205 The characteristic long term performance shall be established from relevant tests with cyclic and constantsustained loading covering the relevant stress ranges mean stresses and load durations according to Sec4N1104 and Sec4 N1105206 A safe service life equation of the following form is used

where σpeak is the peak stress of the stress cycle σtrough is the stress at the trough of the stress cycle and fF isthe characteristic tensile strength of the bar The material factor γFssa accounts for the duration of the loadingThe coefficient C is a material dependent coefficient determined from cyclic fatigue tests to obtain acharacteristic low curve207 In design the load duration used in the damage accumulation shall not be taken less than 5 years in eachstress block208 Prestressed FRP reinforcement shall be checked for safe service life using the formulation in M206above for non- prestressed FRP reinforcement

M 300 Bending moment and axial force301 Stresses in concrete and reinforcement shall be calculated based on a realistic stress-strain relationshipThe effects of shrinkage and creep may be taken into account when calculating stressesFor concrete subject to compression frd is taken equal fcd302 If a more accurate calculation is not performed stresses in concrete and reinforcement can be calculatedwith a linear stress distribution in the compression zone The calculations may be based on a Youngrsquos modulusequal to 08 Eck for the concreteIn such a calculation the reference strength frd of the concrete in compression can be taken as

frd = α middot fcd

The value of α may be calculated as α = 13 ndash 03 β gt 10

Table M2 Level of Stress Variations (MPa)

Δσ gt 235 235 gt Δσ gt 65 65 gt Δσ gt 40C3 157 1335 1697C4 45 35 55

( )

minus

minus=

ssaF

F

ssaF

F

f

trough

f

peak

CN

1

log

γ

σ

where

β = the ratio between the numerically smallest and largest stresses acting simultaneously in the localcompressive concrete zone The distance between the points used when calculating β shall not exceed300 mm (0 lt β lt 10)

303 For FRP reinforcement the stress level in the concrete defined in M302 shall be calculated using thedesign Youngs modulus of FRP reinforcement EFd The stress level in the FRP shall be determined based oncracked sections and stress strain curves for concrete as given in M302 For the FRP reinforcement a linearstress-strain curve shall be applied in the calculations

M 400 Shear force

401 The design life at tensile failure of concrete without shear reinforcement can be calculated in accordancewith M201

σmaxfrd shall be replaced by VmaxVcd

σminfrd shall be replaced by VminVcd

402 For those stress-blocks where the shear force changes sign the denominator in the formula for log N inM201 shall be replaced by

1 + VminVcd

If the shear force changes sign the calculation shall if necessary be performed with both the positive andnegative values for Vmax and Vmin respectively in the formulas above

Vcd shall be calculated in accordance with F200

The factor Cl shall be taken as

120 for structures in air where the shear force does not change sign100 for structures in air where the shear force changes sign and for structures in water where the shear forcedoes not change sign80 for structures in water where the shear force changes sign

403 The design life at tensile failure of concrete for structures with shear reinforcement can be calculated inaccordance with M201 by assuming the concrete at all load levels to transfer a portion of the acting shear forceequal to the ratio of the concrete to the combined shear capacity of concrete and shear reinforcement Whencalculating the shear contribution of the concrete the tensile strength of the concrete shall be reduced to 05 ftdAlternatively the total shear force may be assumed to be carried by the shear reinforcement The design life ofthe concrete at tensile shear failure shall be demonstrated in accordance with M100

404 The design life of the shear reinforcement can be calculated in accordance with M202 to M204 for steelreinforcement and M205 to M206 for FRP reinforcement by assuming the shear reinforcement at all loadlevels to transfer a portion of the acting shear force equal to the ratio of the shear reinforcement to the combinedshear capacity of the shear reinforcement and the concrete calculated with a reduced tensile strength equal to05 ftd The stresses in the shear reinforcement shall be calculated based on an assumed truss model with thecompression struts inclined at 45deg

405 If the shear force changes sign account of this shall be made when calculating the number of stress cyclesin the shear reinforcement

406 The design life at compression failure of concrete can be calculated in accordance with M201

σmaxfrd shall be replaced by VmaxVccd

σminfrd shall be replaced by VminVccd

For those stress-blocks where the shear force changes sign use Vmin = 0

Vccd shall be calculated in accordance with F206

The factor Cl shall be entered with the values given in M402

407 In addition to the checks required above the expected design life of cross sections subjected tosimultaneously acting axial forces shall be calculated from the principal compressive stresses at the mid-heightof the cross section The shear stresses in this case may be assumed constant over a height corresponding to theinternal lever arm which may be taken as 09 middot d The reference stress of the concrete frd shall be taken as fcd

M 500 Anchorage and splicing

501 Demonstration of the design life for force development can be performed in accordance with M201

σmaxfrd shall be replaced by τbmaxfbd

σminfrd shall be replaced by τbminfbd

The bond strength fbd shall be calculated in accordance with K116

The bond stress τb shall be taken asτb = 025 middot φ middot σs lb

502 For structures in air Cl shall be 120 for structures in water Cl shall be 100 If the bond stresses changesign this reversible effect on fatigue life shall be especially considered when evaluating the fatigue life

N Accidental Limit State

N 100 General101 Structural calculations for an accidental limit state shall document the capacity of the structure Thecalculations can be performed according to the regulations of this clause and D E F G H I J K L and P102 The material coefficients are given in C100103 Strength and strain properties are as given in C100 to C400 The strain limits εcu and εsu may howeverbe given particular assessment104 Structures in Safety classes 2 and 3 (see Sec2 A300) shall be designed in such a way that an accidentalload will not cause extensive failure Offshore structures are generally defined belonging to safety class 3The design may permit local damage and displacements exceeding those which are normally assumed bydesign in the ultimate limit state and structural models and load transferring mechanisms which are normallynot permitted may be assumed

N 200 Explosion and impact201 For explosion loads and impact type loads an increased Youngrsquos modulus and material strength basedon a documented relationship between strength and strain rate may be taken into account The assumed strainrate in the structure shall be documented202 The structural calculations may take account of the load variation with time and the dynamic propertiesof the structure

N 300 Fire301 Required fire resistance is determined in one of the following ways

mdash An offshore structure shall be designed to resist a fire in accordance with the requirements of DNV-OS-A101 if no other requirements for the actual structure are provided from National Building Code or otherNational Regulations

mdash For structures where the National Building Regulations give requirements to fire resistance as a functionof fire loading the fire loading is calculated and the required fire resistance is determined in accordancewith the National Building Code

mdash Necessary fire resistance can be determined based on calculated fire loading and fire duration or atemperature-time curve for those cases which are not covered by the National Building Code

302 Structures can be demonstrated to have adequate fire resistance according to one of the followingmethods

mdash calculation in accordance with N303mdash use of other Internationally accepted methodsmdash testing in accordance with an accepted international standard

The adequacy of the fire resistance shall be documented303 The temperature distribution in the structure is determined based on the actual temperaturetime curveand the required fire resistance taking the effects of insulation and other relevant factors into considerationThe strength properties of the materials as a function of the temperature are as given in Sec4 C310 for concreteand C304 for steel reinforcement Special strength properties shall be applied for concrete exposed totemperatures down to cryogenic temperature Reference is made to DNV-OS-C503The strain properties of the concrete are as given in Sec5 E207 The strain properties of the steel reinforcementare as given in Sec5 E208A stress-strain diagram similar to that applicable for the ultimate limit state with the stress ordinate reducedcan be assumed for the concrete when calculating the capacityDisplacements and forces caused by the temperature changes in the structure shall be taken into account in thedesignThe strength properties of FRP as a function of temperature shall be derived by testing304 The structure shall be so detailed that it maintains the required load bearing ability for the requiredperiod An appropriate geometrical form which reduces the risk of spalling of the concrete cover shall besought The reinforcement shall be so detailed that in the event of spalling of concrete cover at laps andanchorages the reinforcement still has adequate capacity

305 The temperature insulation ability and gas tightness of partitioning structures shall be demonstrated inthe accidental limit state of fire

O Serviceability Limit State

O 100 General101 When calculating action effects in the serviceability limit state the mode of behaviour of the structure inthis limit state shall govern the choice of analytical modelThe design resistance in SLS is normally related to criteria for

mdash durabilitymdash limitation of crackingmdash tightnessmdash limitation of deflections and vibrations

102 The properties of the materials under short - and long-term actions and the effect of shrinkagetemperature and imposed displacements if any shall be taken into accountCracking of concrete shall be limited so that it will not impair the function or durability of the structure Thecrack size is controlled by ensuring that the predicted crack width by calculations is within the nominalcharacteristic crack width limits in Table O2103 When it is necessary to ensure tightness of compartments against leakage due to externalinternalpressure difference the concrete section shall be designed with a permanent boundary compression zone seeO600104 Concrete structures shall have at least a minimum amount of reinforcement to provide adequate abilityfor crack distribution and resistance against minor load effects not accounted for in design105 The material coefficients (γm) for concrete and reinforcement are given in C100106 In the analysis and structural design it shall be ensured that displacements and cracks spalling ofconcrete and other local failures are not of such a nature that they make the structure unfit for its purpose in theserviceability limit state nor alter the assumptions made when designing in the other limit states

O 200 Durability201 For concrete structures of permanent character dependent on the environmental conditions to which thestructure is exposed a material composition shall be selected in accordance with Section 4 202 Concrete structureselements shall be classified in exposure classes according to Table O1 Exposureclasses are related to the environmental conditions in accordance with EN 206-1

Table O1 Exposure classes related to environmental conditions in accordance with EN 206-1

Class designation Description of the environment Informative examples where exposure classes may occur

1 No risk of corrosion attack

X0

For concrete without reinforcement or embedded metal all exposures except where there is freezethaw abrasion or chemical attackFor concrete with reinforcement or embedded metal very dry

Concrete exposed to very low air humidity

2 Corrosion induced by carbonationXC1 Dry or permanently wet Concrete permanently submerged in water

XC2 Wet rarely dryConcrete surfaces subject to long-term water contactMany foundations

XC3 Moderate humidity External concrete sheltered from rain

XC4 Cyclic wet and dry Concrete surfaces subject to water contact not within exposure class XC2

3 Corrosion induced by chlorides

XD1 Moderate humidity Concrete surfaces exposed to airborne chlorides

XD2 Wet rarely dry Concrete components exposed to industrial waters containing chlorides

XD3 Cyclic wet and dry Concrete components exposed to spray containing chlorides

For structures of exposure class XSA the requirements for material mixtures shall be considered in relation tothe chosen protective measures If the concrete may become exposed to the aggressive environment at leastthe requirements for XS3 shall be fulfilled

O 300 Crack width limitations

301 When calculating crack widths for comparison with the values in Table O2 long-term actions shall beapplied in combination with short-term actions The short-term actions shall be chosen so that the crack widthcriterion will not be exceeded more than 100 times during the design life of the structure

302 If more accurate values are not known for short-term but frequently repeated actions such as wind trafficand wave actions 50 of the characteristic load as defined in Section 5 may be applied For other variableactions that rarely reach their characteristic value 100 of the long-term part of the actions in combinationwith 40 of the short-term part of the actions may be applied

Concrete structures with steel reinforcement

303 In order to protect the steel reinforcement against corrosion and to ensure the structural performance thereinforcement shall have a minimum concrete cover as given in Q200 and the nominal characteristic crackwidths calculated in accordance with O800 shall be limited as given in Table O2

304 Cold-worked prestressed reinforcement having a stress exceeding 400 MPa and reinforcement withdiameter less than 5 mm shall be considered as reinforcement sensitive to corrosion Other types ofreinforcement can be considered as slightly sensitive to corrosion

4 Corrosion induced by chlorides from sea water

XS1 Exposed to airborne salt but not in direct contact with sea water Structures near to or on the coast

XS2 Permanently submerged Parts of marine structuresXS3 Tidal splash and spay zones Parts of marine structures

5 FreezeThaw attack

XF1 Moderate water saturation without de-icing agent Vertical concrete surfaces exposed to rain and freezing

XF2 Moderate water saturation with de-icing agent Vertical concrete surfaces exposed to freezing and airborne de-icing agents

XF3 High water saturation without de-icing agents Horizontal concrete surfaces exposed to rain and freezing

XF4 High water saturation with de-icing agents or seawater

Concrete surfaces exposed to direct spray containing de-icing agents and freezingSplash zone of marine structures exposed to freezing

6 Chemical attack

XA1 Slightly aggressive chemical environment according to EN 206-1 Table 2

Concrete exposed to natural soils and ground water

XA2 Moderately aggressive chemical environment according to EN 206-1 Table 2

XA3 Highly aggressive chemical environment according to EN 206-1 Table 2

7 Special aggressive environment

XSAStructures exposed to strong chemical attack which are not covered by the other classes and will require additional protective measures

Structures exposed to fluids with low pH-value

Table O2 Limiting values of nominal characteristic crack width wk

ExposureClass

Reinforcement sensitive to corrosion

wk

Reinforcement slightly sensitive to corrosion

wk

XSA Special consideration

Special considerations

XD1 XD2 XD3 XS1 XS3 XF2 XF3 XF4 XA3 020 mm 030 mmXC1 XC2 XC3 XC4 XS2 XF1 XA1 XA2 020 mm 040 mmX0 040 mm -

Table O1 Exposure classes related to environmental conditions in accordance with EN 206-1 (Continued)

305 For structures permanently submerged in saline water the crack width requirements given for exposureclass XS2 in Table O2 apply Exceptions are structures with water on one side and air on the opposite side forwhich the requirements for XS3 apply on the air side306 The crack width limitations given in Table O2 are related to the crack width at a distance from thereinforcement corresponding to the minimum concrete cover in accordance with Table Q2 When the concrete cover is larger the nominal crack width when comparing with the values in Table O2 maybe taken as

where

wok = crack width calculated in accordance with O800c1 = minimum concrete cover see Table Q2c2 = actual nominal concrete cover

307 If reinforcement sensitive to corrosion is placed on the inside of reinforcement slightly sensitive tocorrosion and with larger concrete cover than the minimum requirement the nominal crack width whencomparing with the requirements for corrosion sensitive reinforcement in Table O2 may be taken as

W2k = w1k middot εs2 εs1

where

εs1 = tensile strain in reinforcement slightly sensitive to corrosion on the side with highest strainεs2 = tensile strain at the level of the reinforcement sensitive to corrosion

308 For cross sections with reinforcement sensitive to corrosion the crack limitation requirements do alsoapply for cracks parallel to this reinforcement309 For short periods in the construction phase the crack width limitation given in Table O2 may beexceeded by up to 100 but not more than 060 mm in the classes where limiting values are specified whenthe anticipated actions are applied 310 The strain in the reinforcement shall not exceed 90 of the yield strain during short period loading inthe construction phase for 100 of characteristic loads (γf = 10 for all loads) including moments Concrete structures with FRP reinforcement311 Crack width calculation may be avoided when the strain in the FRP reinforcement is limited to 4permil underSLS loading for structures where the size of the crack is critical Likewise crack width calculations may beignored for structures where the strain in the FRP reinforcement is less than 6permil and the size of the crack widthis not critical312 Although no specific crack width requirement is specified for FRP reinforcement due to durabilityconsiderations the crack width shall be limited due to considerations based on appearance This may varybased on application like offshore structures foundations water tight structures oil containment structures etc

Guidance noteFor structures in which the concrete surface is visible wk lt 05 mmFor structures not visible wk lt 08 mm

See O600 for special crack width requirements in order to ensure tightness against leakage of fluid313 Crack width shall be calculated based on SLS loading conditions and account shall be taken of the actualconcrete cover and spacing between the reinforcement

O 400 Displacements401 It shall be demonstrated by calculations that the displacements are not harmful if the use of the structureor connected structural members imposes limits to the magnitude of the displacements402 Normally the tensile strength of the concrete shall be ignored when calculating displacements Howeverit may be taken into account that the concrete between the cracks will reduce the average strain of thereinforcement and thus increase the stiffness403 Action effects when calculating displacements shall be determined by use of actions and load factors inaccordance with Sec5 D100 Effect of pre-stressing forces shall be taken into account in accordance withSec5 CWhen calculating long-term displacements the variation of the variable actions with time may be taken intoaccount

okokk wc

cww sdotgtsdot= 70

2

11

O 500 Vibrations501 If a structure and the actions are such that significant vibrations may take place it shall be demonstratedthat these are acceptable for the use of the structure

O 600 Tightness against leakages of fluids601 In structures where requirements to tightness against fluid leakages are specified concrete with lowpermeability and suitable material composition shall be selected see Section 4

mdash the acting tensile stresses and nominal crack widths shall be limitedmdash geometrical form and dimensions shall be chosen which permit a proper placing of the concrete

602 Members subjected to an externalinternal hydrostatic pressure difference shall be designed with apermanent compression zone not less than the larger of

mdash 025 middot hmdash values as given in Table O3

The above applies for the operating design condition using ULS combination b) (see Sec5 D200) except thata load coefficient of 05 is used instead of 13 for the environmental load (E)603 Oil containment structures with an ambient internal oil pressure greater than or equal to the ambientexternal water pressure (including pressure fluctuations due to waves) shall be designed with a minimummembrane compressive stress equal to 05 MPa for the operation design condition using ULS combination b) (seeSec5 D200) except that a load coefficient of 05 is used instead of 13 for the environmental load (E) Howeverthis does not apply if other constructional arrangements eg special barriers are used to prevent oil leakage604 In structures where requirements to tightness against leakages are specified the reinforcement shall meetthe requirements for minimum reinforcement for structures with special requirements to limitation of crackwidths see Q705 and Q1102

O 700 Tightness against leakage of gas701 Concrete is not gas tight and special measures shall be taken to ensure gas tight concrete structures whenthis is required

O 800 Crack width calculationCrack width calculation for concrete structures with steel reinforcement801 Concrete may be considered as uncracked if the principal tensile stress σ1 does not exceed ftnk1With combined axial tensile force and bending moment the following condition applies

With combined axial compression force and bending moment the following condition applies

where

σN = stress due to axial force (tension positive)σM = edge stress due to bending alone (tension positive)ftn = normalized structural tensile strength of concrete (Table C1 and Table C2)k1 = constant used in calculations of crack width (Table O4)kw = coefficient dependent on cross-sectional height h = 15 ndash hh1 ge 10 where h1 = 10 m

Table O3 Depth of compression zone versus pressure differencePressure Difference

(kPa)Depth of Compression Zone

(mm)lt 150 100gt 150 200

( )1k

fkk tnw

MNw lt+σσ

( )1k

fk tnwMN lt+σσ

In cases where the corrosion sensitive reinforcement is placed only in the compression zone then the values ofk1 for ldquoNone Corrosion Sensitive Reinforcementrdquo can be used

Stresses caused by temperatures creep shrinkage deformations etc shall be included in the evaluationprovided the crack width is influenced by these parameters

If a high predicted cracking load (cracking moment) is non-conservative then ftk shall be used in thecalculations and k1 shall be taken as 10

802 The characteristic crack width of a reinforced concrete member exposed to tensile forces and shrinkageof concrete can in general be calculated from

wk = lsk middot (εsm - εcm - εcs)

where

lsk = the influence length of the crack some slippage in the bond between reinforcement and concrete mayoccur

εsm = the mean principal tensile strain in the reinforcement in the crackrsquos influence length at the outer layerof the reinforcement

εcm = mean stress dependent tensile strain in the concrete at the same layer and over the same length as εsmεcs = the free shrinkage strain of the concrete (negative value)

The crack widths may be calculated using the methods outlined in Appendix E

803 If no documentation of the characteristic crack widths is performed in accordance with O802 then therequirements for limitation of crack widths may be considered as satisfied if the actual stresses in thereinforcement do not exceed the values in Table O5

The listed stresses apply to cracks perpendicular to the direction of the reinforcement and only when theamount of tensile reinforcement is no less than 0005 Ac

804 In the calculations of stresses in reinforcement or crack width in structures exposed to water pressure ofmagnitude sufficient to influence the calculated stress level or crack width then the impact of the waterpressure in the crack shall be included in the calculation Generally it is considered that this effect is importantfor structures located at a water depth of 100 metre or more

Crack width calculation for concrete structures with FRP reinforcement

805 In crack width calculations the load magnitude for offshore structures may be determined based onprinciples provided in O300

806 A guideline for prediction of the characteristic crack width in FRP reinforced structures is provided inAppendix E

Stresses and strain caused by temperatures creep shrinkage deformations etc shall be included in theevaluation provided the crack width is influenced by these parameters

The above stresses and strains shall be included in the strain value εsm when calculating crack width for themember according to Appendix E

Table O4 Values of constant parameter k1

ExposureClass

Corrosion sensitive Reinforcement

None Corrosion Sensitive Reinforcement

XSA Special consideration Special considerationXD1 XD2 XD3 XS1 XS2 XS3 XF2 XF3 XF4 XA3 20 15

XC1 XC2 XC3 XC4 XF1 XA1 XA2 15 10

X0 10 10

Table O5 Stress limitations for simplified documentation of satisfactory state of cracking

Nominal characteristic crack width

Type of load effect

Stress in reinforcement (MPa)Spacing between the bars or bundles of bars (mm)

100 mm 150 mm 200 mm 250 mm 300 mm

Wk = 04 mmBending 360 MPa 320 MPa 280 MPa 240 MPa 200 MPaTension 300 MPa 230 MPa 210 MPa 200 MPa 190 MPa

Guidance noteThis guideline shall only be used for FRP reinforced concrete structures In cases where the structural member isreinforced by both steel reinforcement and FRP reinforcement the crack width criteria for steel reinforcementstructures apply

807 Crack width calculation may be avoided when requirements in O311 are met

The same approach may be used for SLS conditions specified in EN1990 for design situations where nodetailed crack width calculations have been carried out and there is no special requirement to limit the crackwidth for reasons of appearances

It shall be noted that this approach generally for structural members with sufficient tension reinforcement willyield acceptable crack width However for structures with small cover and side net the approach has so farshown to under-predict the crack width

O 900 Limitation of stresses in prestressed structures

901 The stresses in the prestressed steel reinforcement shall for no combination of actions exceed 08 fyalternatively 08 middot f01

During prestressing however stresses up to 085 middot fy alternatively 085 middot f01 may be permitted provided it isdocumented that this does not harm the steel and if the prestressing force is measured directly by accurateequipment

902 The stress in the prestressed FRP reinforcement shall under no circumstances exceed 80 of the designstrength of the FRP reinforcement for load combination type I as defined in C108

903 When a prestressing force acts within a concrete compression zone the stress at the outer compressivefibre of the concrete shall not exceed the lesser of 06 middot fcckj or 05 middot fcck in the serviceability limit state

The outer compressive fibre stress shall be calculated assuming a linear distribution of stresses presuming acracked section over the cross section fcckj shall be taken as the strength of the concrete at the time when theload in question is applied Creep and shrinkage of the concrete may be taken into account when calculatingthe stresses

O 1000 Freezethaw cycles

1001 The general requirement to freezethaw resistance of concrete is given in Sec4 C206 Whereappropriate the freezethaw resistance of the concrete shall be evaluated This evaluation shall take account ofthe humidity of the concrete and the number of freezethaw cycles the concrete is likely to be subjected toduring its lifetime Special attention shall be given to freezethaw of the concrete in the splash zone

Special frost resistant concrete may be required based on this evaluation

O 1100 Temperature effects

1101 Thermal stresses due to temperature effects shall be taken into account when relevant Relevantmaterial properties shall be used Reference is made to Sec5 E300

O 1200 Deflection prediction for FRP reinforced concrete members

1201 This section applies to the prediction of deflections in beam elements Deflections of more complexstructures need to be documented accordingly

1202 In predicting the long term deflection of a structural member reinforced by FRP due account shall betaken of creep effects in concrete and relaxation in FRP

1203 The displacement of the FRP reinforced member may be calculated from a combination of non-crackedand cracked concrete member

1204 For displacement due to bending initially the deflection is predicted for the un-cracked member withfull bending stiffness up to the cracking load (ftn see Table C1 and Table C2) The deflection of the beambeyond the cracking load may be calculated using the cracked moment of inertia of the concrete beam

Guidance noteThe deflection of FRP reinforced concrete structures in bending may be determined based on the following generalprincipal

1) Predict the cracking load Pcr of the structural element under investigation 2) Calculate the deflection δE for the cracking load Pcr using elastic properties for concrete Both the E modulus of

concrete and FRP reinforcement should be modified to account for possible creep in concrete and relaxation inFRP

3) Based on beam formulations calculate the cracked section modulus for the structural element under investigationThe structural element may be composed of smaller structural element each with different cracked sectionmodulus

4) Calculate the deflection of the structural element δC1 for the load in excess of the cracking load ie P ndash Pcr

5) Modify the predicted cracked deflection δC1 by the common reduction factor to kdB 6) The final deflection at a given point in the structural element may be predicted by the following formula

δC1 = δE + kdB δC1

P Design by Testing

P 100 General101 Concrete structures can be designed either by testing or by a combination of calculation and testing Thisapplies to all limit states defined in B201102 Testing can be applied to a complete structural member (eg a beam) a part of a structure (eg a beamsupport) or to a detail of a structure (eg a fixing device to a beam) The test can cover all properties of thestructure or only certain properties which are relevant in the particular caseNormally the test shall be carried out on specimens of the same size as the object for which the properties shallbe tested If the test specimen is not of the true size the model and the scale factors shall be evaluated separately103 The rules of the standard with regard to dimensions including the rules for detailing of reinforcement inQ shall also apply to structures and parts of structures dimensioned by testing Deviations from these rules canbe undertaken provided it is demonstrated by the test that such deviations are justified

P 200 The test specimen201 When determining the dimensions of the test specimen tolerances which exceed those given C500 worstcase condition shall be taken into account More stringent tolerances may be considered202 The test specimen may be produced with nominal dimensions if the specified tolerances are less than therequirements to C500 If the accepted deviations have been accounted for in a conservative way the reducedmaterial factors in Table C1 may be used The tolerances may be considered incorporated if the test specimenis produced in the same form as the component to be dimensioned by testing203 The effect of unintended eccentricity inclination and curvature shall be taken into account as given inA301 D103 and E106 to E108204 When determining the material strength in the test specimen characteristic strengths equal to thoseprescribed for production of the component should be aimed at205 If the concrete strength is governing for the test result the concrete used in the test specimen shall havea strength approximately equal to but not higher than the specified characteristic concrete strength for thecomponent in question206 If there are changes regarding concrete mix constituents or concrete supplier during the productionprocess of the component the compressive strength and the tensile strength shall be tested when the specimensare tested and when alterations are made207 The test results for the material strength taken during production of the components shall not be less thanthose taken from the test specimen unless it can be proved that smaller values are justifiable208 If the reinforcement is considered to be governing for the test result the same type of reinforcement shallbe used as is intended for the structure to be dimensioned The yield strength - or 01 limit - shall be determinedIf the tested strength deviates from the prescribed strength of the reinforcement this shall be taken into accountwhen determining the capacity of the test specimen on the basis of the tested yield strength and the nominalcharacteristic yield strength of the reinforcement used209 In order to determine the failure load for certain failure modes it may be necessary to prevent failurescaused by other failure modes with possible lower failure load In such cases it may be necessary to modifygeometry concrete strength or amount and strength of the reinforcement If such means have been used it shallbe clearly stated in the test report It shall be assessed whether such modifications will influence the capacityfor the failure mode which is tested

P 300 Design actions301 The design actions shall be determined with the same load coefficients used when the capacity isdetermined by calculation normally in accordance with Sec5 D302 The design actions shall be selected so that they are representative for the anticipated actions on thestructure if necessary through simulation

P 400 Test procedure401 A test procedure shall be made see also P600402 Preparation and storing of the test specimen shall follow methods which are representative for theproduction of the components

403 A test record shall be prepared showing observations made during testing with indication of time andthe corresponding action levels

404 All test records shall be signed by the person responsible for the testing

P 500 Processing of the test results

501 In general the test shall comprise not less than three specimens Characteristic value (Rk) mean value(Rm) and standard deviation (s) shall be determined The characteristic value can be calculated according tothe formula

Rk = Rm - w s

where

w has the following values

502 If the standard deviation is particularly high or some of the test results highly deviate from the others thecauses of this should be analysed

503 The design value of the capacity is obtained by dividing the characteristic capacity with a materialcoefficient which is dependent of the mode of failure for the capacity of the component as detailed in P504below The material coefficients given in B400 shall be used The appropriate value of material coefficient shallbe used dependent on how tolerances are accounted for in the design and in the test specimen

504 The design value of the capacity shall be determined with the material coefficient for concrete for allmodes of failure where the concrete is governing for the capacity The design value of the capacity can bedetermined with the material coefficient for reinforcement if the mode of failure is governed by thereinforcement provided it is proved that a failure caused by failure of the concrete would not give a lowerdesign value of the capacity

505 For failure modes where the concrete and the reinforcement jointly contribute to the capacity thematerial coefficient for concrete shall be used unless a more detailed examination is performed

For FRP reinforced concrete structures a higher material factor for FRP reinforcement shall be used Unless amore detailed examination of the failure mode is carried out the material coefficient of FRP for the appropriateload combination specified in Section6 C108 shall be applied

506 If reinforced components have failures in an area where the reinforcement is insufficiently anchored asmay be the case with shear and bond failures in hollow core slab elements on short supports the design valueof the capacity for these failure modes shall be calculated with the material coefficient for unreinforcedconcrete increased by 50

507 For unreinforced components a material coefficient of twice the value given in C102 shall be used if thefailure mode is governed by the tensile strength of the concrete Such an increase of the material coefficient isnot required for steel fibre reinforced elements if the volume of steel fibres exceeds 1 of the concrete volume

Further all the requirement of C600 shall be fulfilled

508 If the characteristic crack width is to be determined only highly strained areas shall be considered

509 The component may be treated by areas where each area is evaluated separately

510 The characteristic value may be set equal to the highest measured value of crack width or displacementif the test does not give sufficient basis for a statistical calculation of the characteristic value

P 600 Test report

601 The execution and the results from the test shall be recorded in a test report to be signed by the person incharge of the test

602 The test report shall as a minimum comprise the following information

a) aim of the test and the principles used for selection of testing object (specimen)

b) material parameters such as class of concrete and reinforcement type and properties of the aggregatestype and properties of additives

c) detailed geometry of the specimen including reinforcement layout

d) result from the testing of materials strength values for the concrete and reinforcement

e) preparation of the specimen (or component) identification number dimensions weight curing conditionsstoring and handling

f) Instruments used during the test

Number of specimens 3 4-5 6-10 11-20 gt 20

w 25 20 17 15 14

g) actions

h) results of the test test records

i) interpretation of the results calculation of design values of capacities

Q Rules for Detailing of Reinforcement

Q 100 Positioning

101 Reinforcement shall be placed in such a way that concreting will not be obstructed and so that sufficientbond anchorage corrosion protection and fire resistance is achieved

The positions of ribbed bars may be designed in accordance with the given minimum spacing without regardto the ribs but the actual outer dimensions shall be taken into account when calculating clearance for placingof reinforcement and execution of the concreting

The positioning of reinforcement shall be designed so that the given requirements to the concrete cover can beobtained in compliance with the specified tolerances

102 Ribbed bars may be arranged in bundles Bundles shall not consist of more than four bars includingoverlapping (see Q303) Normally the bars shall be arranged so that the bundle has the least possible perimeter

103 When using welded mesh fabric in accordance with approved International Standard two layers may beplaced directly against each other

104 Ducts for prestressed reinforcement may be assembled in groups when this does not obstruct theconcreting of the cross section or the direct transfer of forces to the concrete At the anchorages specialrequirements for placing will apply for the various tendon systems

105 With respect to concreting the free distance between reinforcement units in one layer where concrete hasto pass through during casting shall be no less than Dmax + 5 mm

Free distance between reinforcement bars in one layer and between each reinforcement layer if more than onelayer is used is dependent on the exposure class of the concrete structure Table Q1 shows the limitations foreach exposure class See O200 for exposure class definitions

In addition the free distance between reinforcement shall normally be no less than the outer diameter ofbundles or ducts

106 With respect to the conditions during concreting of structures that are cast directly on bed-rock hard anddry clay or firm gravel the free distance between the horizontal reinforcement and the ground shall be no lessthan 50 mm

On other types of ground at least a 50 mm thick concrete layer with strength no less than 15 MPa or an equallystable base of another material shall be specified If concrete is used as a base the free distance between thereinforcement and the base shall be at least 30 mm

When concreting in water the horizontal reinforcement shall be placed at least 150 mm above the bottom

107 With regard to anchorage the free distance between ribbed bars bundles of ribbed bars or strands shallbe no less than 2 middot φ where φ is the nominal diameter for ribbed bars and strands or the equivalent diameter forbundles based on equivalent cross-sectional area

At lapped splices of individual bars placed next to each other the free distance to adjacent bars shall be no lessthan 15 middot φ

Q 200 Concrete cover

201 The concrete cover shall not be less than φ for ribbed bars and bundled bars and 2 middot φ for preposttensioned reinforcement

Table Q1 Minimum distance between reinforcement bars with respect to exposure class Exposure Class Free distance between reinforcement

bars in one layerFree distance between each layer of

reinforcement barsXSA Special consideration Special considerationXD1 XD2 XD3 XS1 XS2 XS3 XF2 XF3 XF4 XA3 45 mm 35 mm

X0 XC1 XC2 XC3 XC4 XF1 XA1 XA2 40 mm 25 mm

202 Based on requirements to corrosion protection the concrete cover shall not be less than the values givenin Table Q2 for structures with steel reinforcement See O200 for exposure class definitions

The concrete cover between vertical formed surfaces and horizontal reinforcement units shall normally be noless than the diameter of the reinforcement unit and no less than Dmax + 5 mmWhen concreting in water the distance between reinforcement bars bundles and layers shall be no less than100 mm and the concrete cover no less than 70 mmEnd surfaces of tensioned reinforcement in precast elements in very aggressive environment represented byXSA XD1 XD2 XD3 XS1 XS2 XS3 XF2 XF3 XF4 XA3 shall be protectedAdequate corrosion protection of the end anchorage system of post-tensioned reinforcement shall bedocumented for the actual exposure classPost-tension bars shall be placed in tight pipes injected with grout grease etc203 For structures reinforced with FRP bars the minimum concrete cover to the longitudinal reinforcementshall be taken as the minimum of

mdash the equivalent diameter Deq of the group of FRP bars or mdash 15 times diameter of the aggregate used in the concrete mix

For bundled groups of FRP bars the diameter of the bar group shall be taken as the equivalent diameter basedon area of FRP

where

AF BAR = area of each FRP barDeq = equivalent diameter of group of barsn = number of FRP bars in group204 For FRP reinforcement concrete cover to the stirrups of beams and columns may be taken as minimumfrac12 the diameter of the FRP stirrup205 For structures exposed to fire the requirement to minimum concrete cover shall additionally bedetermined from fire resistant requirements

Q 300 Splicing301 Reinforcement bars may be spliced by lapping couplers or welding Splices shall be shown on thedrawings

mdash splices shall be staggered and as far as possible also placed in moderately strained areas of the structureLaps may be assumed as distributed if the distance from centre to centre of the splices is greater than thedevelopment length calculated in accordance with Sec6 K

302 At laps of tensile reinforcement necessary development length shall at least be taken equal to thenecessary development length calculated in accordance with K Plain bars shall in addition have end hooks303 Bars and bundles that are spliced by lapping shall be in contact with each otherAreas where a transfer of forces is required between adjacent bars which are not placed against each other canbe designed in accordance with I103 and I104Lapped reinforcement shall have a transverse reinforcement distributed along the lap length and this shall havea total cross-sectional area of at least 70 of the cross-sectional area of one lapped bar

Table Q2 Minimum concrete cover due to corrosion protection

Design Lifetime 50 years Design Lifetime 100 years

Exposure Class Reinforcement

sensitive to corrosion

Reinforcement slightly sensitive to

corrosion

XSA Special considerations

XS3 XF4 60 mm 50 mm 70 mm 60 mmXD1 XD2 XD3 XS1 XS2 XF2 XF3 XF4 XA3

50 mm 40 mm 60 mm 50 mm

XC2 XC3 XC4 XF1 XA1 XA2 35 mm 25 mm 45 mm 35 mm

X0 XC1 25 mm 15 mm 35 mm 25 mm

πBARF

eq

AnD 4 sdotsdot

=

If the lapped bar has a diameter greater or equal to 16 mm then transverse reinforcement shall be providedequally spaced over the outer third part of the lapped jointWhen the equivalent diameter is larger than 36 mm for normal aggregate concrete and 32 mm for lightweightaggregate concrete then the bars in bundles with up to three bars shall be lapped individually in such a waythat there will be no more than four bars in any section The lap length shall be calculated in accordance withK108Laps in tensile members shall be staggered and the laps shall be enclosed by closed stirrups with a total cross-sectional area at least equal to twice the area of the spliced bar and with spacing no larger than 10 times thediameter of one spliced bar

Q 400 Bending of steel reinforcing bars401 Bent reinforcement shall be designed with the following set of mandrel diameters (in mm) 16 20 2532 40 50 63 80 89 100 125 160 200 250 320 400 500 and 630402 Reinforcement shall not be bent around mandrel diameters less than 15 times the diameter of the testmandrel used when demonstrating the bending properties of the steel or at a lower temperature than thebending properties have been documented for The minimum mandrel diameter is given in Table Q3 forreinforcement in accordance with EN 10025 or EN 10080 For reinforcement in accordance with otherInternational Standards like ISO6935 ASTM and ACI bending criteria shall be in accordance with theapplicable material standard Use of mandrel diameters less than permissible diameters given in Table Q4requires documentation in accordance with L112

403 The temperature in the reinforcement shall be no less than -10degC during bending 404 For normal bent reinforcement in accordance with EN 10025 or EN 10080 the mandrel diameters givenin Table Q4 may be used without documentation in accordance with L112 For stirrups and anchorage hookssee Q408

405 Bent reinforcement which will be straightened or re-bent shall not have been bent around a mandreldiameter less than 15 times the diameter of the test mandrel used when demonstrating the ageing properties ofthe steelFor reinforcement in accordance with EN 10025 or EN 10080 the mandrel diameters given in Table Q5 can beused

Reinforcement which will be straightened or re-bent shall not have a temperature less than -10degC for bardiameters 12 mm and less For larger dimensions the temperature shall not be below 0degC

Table Q3 Permitted mandrel diameter (mm) for bending of reinforcement which satisfies the requirements of EN 10025 or EN 10080Reinforcement Type

Bar Diameter (mm)5 6 7 8 10 11 12 14 16 20 25 32

B500Ca) 16 20 25 32 40 50 80 125 160

B500Ba) b) 20 32 40 50 63 8032 40 50 63 89 100

B500A 25 32 32 40 50 50 63G250 20 25 32 40a) Warm rolled ribbed reinforcement produced with controlled cooling can be bent with temperatures down to 20degC below zerob) For reinforcement type B500B mandrel types in the upper line may be used for bending at temperatures above 0degC

Table Q4 Permissible mandrel diameter (mm) for bending of reinforcement without compliance to L112Tensile strength of Reinforcement (fsk) MPa

Bar Diameter (mm)5 6 7 8 10 11 12 14 16 20 25 32

500 100 125 160 160 200 200 250 250 320 400 500 630250 50 63 80 100

Table Q5 Permissible mandrel diameter (mm) for bending of reinforcement complying with EN 10025 or EN 10080 which shall be rebent or straightened

Reinforcement TypeBar Diameter (mm)

5 6 7 8 10 11 12 14 16 20 25B500C 32 40 50 63 80 100 160 320B500B 63 80 100 125 160 200B500A 50 63 63 80 100 125 125G250 40 50 63 100

Reinforcement which will be straightened or re-bent shall not be used in structural members where thereinforcement will be subjected to fatigue

406 Reinforcement bars of type ldquoTempcorerdquo or similar shall not be heat treated when bending orstraightening

407 Stirrups and anchorage hooks shall be made of reinforcement of weldable quality

408 Verification in accordance with L112 is not required for stirrups and anchorage hooks provided themandrel used has a diameter not larger than 100 mm and a transverse bar with diameter neither less than thediameter of the bent bar nor less than 03 times the diameter of the mandrel used is located in the bendRegardless of the level of stresses such reinforcement shall always have a transverse bar in the bend

The straight part following the bend of anchorage hooks may be placed parallel to the surface if the diameterof the reinforcement bar is not larger than 16 mm If the diameter is larger the straight part shall be bent intothe cross section in such a way that the concrete cover does not spall by straightening the hook when thereinforcement bar is tensioned The bend shall at least be 135deg

409 Welded reinforcement bars with welded attachments can be bent around mandrel diameters inaccordance with Q401 to Q408 provided the distance between the start of the bend and the welding point is noless than four times the diameter of the bar

410 For structures subjected to predominantly static loads the bar can be bent at the welding point with amandrel diameter as given in Table Q4

411 For structures subjected to fatigue loads the diameter of bending for welded wire fabric shall be no lessthan one hundred times the diameter of wire if the weld is located on the outer periphery of the bend or fivehundred times the diameter of the wire if the weld is located on the inside

412 Prestressed reinforcement shall not be bent or placed with a sharper curvature than that giving amaximum stress in the steel - caused by curvature in combination with prestressing - exceeding 95 of theyield stress or of the 01 proof stress Where a sharper curvature is required the steel shall be pre-bent beforebeing placed in the structure This is only permitted if it is demonstrated for the steel type and dimensions inquestion that such pre-bending is not harmful to the performance of the steel as prestressed reinforcement

Q 500 Bending of FRP bars

501 The relationship between strength of the FRP reinforcement and the bend in FRP bars is given in F110

Q 600 Minimum area of reinforcement - General

601 Minimum reinforcement shall be provided so that the reinforcement in addition to securing a minimumcapacity also contributes to preventing large and harmful cracks This is achieved by transferring the tensileforce present when the concrete cracks to a well distributed reinforcement

602 In each individual case the actual structure and state of stresses shall be taken into consideration whendetermining the minimum reinforcement

603 For structures exposed to pressure from liquid or gas shall the numerical value of ftk be replaced by(ftk + 05 pw) in the formulae for calculating the required amount of minimum reinforcement where pw = liquidor gas pressure

604 Through all construction joints a minimum reinforcement no less than the minimum reinforcementrequired for each of the parts concreted together shall normally be specified

605 In structures in a severely aggressive environment and in structures where tightness is particularlyimportant a well distributed reinforcement crossing all concreting joints shall be specified This should have across section that is at least 25 larger than the required minimum reinforcement for the parts that areconcreted together

606 In slabs the prestressing units shall not have larger spacing than six times the thickness of the slab

Q 700 Minimum area of reinforcement - slabsplates

701 A structure or structural member shall be considered as a slab if the width of the cross section is largerthan or equal to 4 times the thickness

702 In general the total depth of the cross-sectional h shall be no less than Li 135 where Li is the distancebetween zero moment points

703 For two-way slab systems the lesser Li for the two span directions shall apply and for cantilever slabs

Li = 2 middot L

Where L is the length of the cantilever

704 Transverse to the main reinforcement and directly on this a continuous minimum reinforcement shall beplaced for steel reinforced members The reinforcement shall have a total cross-sectional area equal to

where

kw = 15 ndash hh1 ge 10h = the total depth of the cross section h1 = 10 mftk = defined in Q603

At inner supports this reinforcement may be distributed with one half in the upper face and one half in the lowerfaceFor FRP reinforced members fsk shall be replaced for the stress in the FRP reinforcement at

mdash 4permil strain for structural members sensitive to visual structural cracks ormdash 6permil strain for structural members not sensitive to visual structural cracksmdash In order to assess the stress corresponding to this strain EFd shall be used

705 In structures where special requirements to limitation of crack widths apply the minimum reinforcementshould be at least twice the value given aboveThe spacing between the secondary reinforcement bars in the same layer shall not exceed three times the slabthickness nor exceed 500 mm706 In the span and over the support a main reinforcement no less than the required minimum reinforcementshall be specified on the tension face In the span and over the support the spacing of the main reinforcementbars shall not exceed twice the slab thickness nor exceed 300 mm When curtailing the main reinforcement thespacing may be increased to four times the thickness or 600 mm707 A portion of the main reinforcement with a cross-sectional area no less than the requirement forminimum reinforcement shall be extended at least a length d beyond the calculated point of zero momentwhere d is the distance from the centroid of the tensile reinforcement to the outer concrete fibre on thecompression side For reinforcement over the support the distance between support and point of zero momentshall not be assumed less than the distance calculated according to the theory of elasticity708 Of the maximum main reinforcement between supports the following portion shall be extended beyondthe theoretical support

mdash 30 at simple supportmdash 25 at fixed support or continuity

709 At simple end support the main reinforcement shall be anchored for a force which at least correspondsto the capacity of the required minimum reinforcement710 In two-ways slab systems these rules apply for both directions of reinforcement711 At end supports a top reinforcement which at least is equal to the required minimum reinforcement shallnormally be provided even if no restraint is assumed in the calculations unless the slab end support is actuallyfully free For one-way slab systems this top reinforcement may be omitted at end supports parallel to the mainreinforcement712 As for inner supports the transverse reinforcement which is calculated in accordance with Q705 andQ706 may be distributed with one half in the upper face and one half in the lower face713 Normally no stirrups or other types of shear reinforcement are required for slabs For steel reinforcedmembers the shear reinforcement shall have a cross-sectional area at least corresponding to (in mm2mm2)

to be taken into account in the shear capacity where ftk is defined in Q603For FRP reinforced members fsk corresponds to the stress in the FRP reinforcement at

mdash 4permil strain for structural members sensitive to visual structural cracks ormdash 6permil strain for structural members not sensitive to visual structural cracksIn order to assess the stress corresponding to this strain EFd shall be used

Q 800 Minimum area of reinforcement - flat slabs801 Flat slabs are slabs with main reinforcement in two directions and supporting columns connected to theslab The head of the column may be enlarged to a capital The slab may be made with or without drop panelabove the capital

sk

tkcws f

fAkA sdotsdotsdotge 250

sk

tksv f

fA sdotge 20

The slab shall have a minimum thickness of

(l ndash 07 middot bk) 30 ge 130 mm for slabs without drop panel(1 ndash 07 middot bk) 35 ge 130 mm for slabs with drop panel

1 is the distance between the centre lines of the columnsbk is the width of the capital at the underside of the slab or the strengthening bk shall not be entered with alower value than the width of the column in the span direction or with a larger value than the valuecorresponding to a 60deg inclination of the face of the capital to the horizontal plane802 For steel reinforced members the slab reinforcement shall have a total cross-sectional area at least equal to

wherekw is in accordance with Q704

ftk = defined in Q603

For FRP reinforced members fsk corresponds to the stress in the FRP reinforcement at

mdash 4permil strain for structural members sensitive to visual structural cracks ormdash 6permil strain for structural members not sensitive to visual structural cracks

In order to assess the stress corresponding to this strain EFd shall be used803 At the middle of the span the spacing of bars shall not exceed 300 mm804 Above columns in flat slabs with prestressed reinforcement without continuous bond a non-prestressedreinforcement in the upper face shall be provided with an area no less than the required area in accordance withthis clause regardless of the state of stresses

Q 900 Minimum area of reinforcement - beams901 The cross-sectional depth h shall normally be no less than Li 35Li is the distance between points of contra-flexure For cantilever beams Li = 2 middot L and L is the length of thecantilever902 Steel reinforced rectangular beams should normally have reinforcement at the tension face at least equal to

where

kw = as given in Q704ftk = defined in Q603

At the compression side the reinforcement should not be less than half of this value if not otherwisedocumented to be sufficient903 Steel reinforced beams with flanges a minimum reinforcement shall be specified for the web as forrectangular beamsFlanges subjected to tension shall be provided with additional reinforcement in accordance with the followingformula

where

Acf = the effective cross section area of the flange hf middot beffbeff = the part of the slab width which according to A400 is assumed as effective when resisting tensile forceshf = the thickness of the flange (the slab)ftk = defined in Q603

In beams where the neutral axis is located near the flange this quantity may be reduced to

In flanges subjected to compression the requirement for minimum reinforcement is

sk

tkcws f

fAkA sdotsdotsdotge 250 in each of the two main directions

sk

tkws f

fhbkA sdotsdotsdotsdotge 250

sk

tkcfs f

fAA ge

sk

tkefffs f

fbhA sdotsdotsdotge 50

sk

tkcfs f

fAA sdotsdotge 250

904 In beams the following fraction of the maximum main reinforcement in the span shall be extendedbeyond the theoretical support

In both cases at least 2 bars shall be extended

At least 30 of the maximum required tensile reinforcement over supports shall either be extended a distancecorresponding to the anchorage length beyond the point where calculated tension in the reinforcement is equalto zero or be bent down as inclined shear reinforcement

905 T-beams which are parallel to the main reinforcement of the slab shall have a transverse topreinforcement above the beam no less than half of the main reinforcement of the slab in the middle of the spanThis top reinforcement shall be extended at least 03 times the span length of the slab to both sides of the beam906 Normally stirrups shall be provided along the entire length of a beam irrespective of the magnitude ofthe acting shear forces In steel reinforced members this stirrup reinforcement shall have a cross-sectional areacorresponding to

where

Ac = the concrete area of a longitudinal section of the beam webα = the angle between stirrups and the longitudinal axis of the beam The angle shall not be taken less than 45degftk = defined in Q603

The tensile strength ftk shall not have a lower value than 255 MPa The distance between the stirrups shallneither exceed 06 h nor 500 mm whatever is the smaller The stirrups shall enclose all tensile reinforcementbars if necessary by means of spliced stirrups In beams with flanged cross section transverse reinforcementoutside the longitudinal reinforcement may be assumed to enclose the longitudinal reinforcement Alongitudinal reinforcement bar shall be placed in all the corners of the stirrups and in any anchorage hooks Thediameter of this longitudinal bar shall be no less than the diameter of the stirrup

If the depth of the beam exceeds 1 200 mm an additional longitudinal surface reinforcement on the faces ofthe beam web shall be provided This reinforcement shall be no less than the required minimum stirrupreinforcement

In prestressed concrete the distance between the stirrups may be up to 08 h if the capacity is sufficient withoutshear reinforcement but no larger than 500 mm In those parts of prestressed beams which have compressionin the entire cross section in the ultimate limit state minimum stirrup area may be reduced to 70 of the aboverequirementsIn wide beams the distance between stirrups or legs of stirrups measured perpendicularly to the longitudinalaxis shall not exceed the depth of the beam see also F100907 For FRP reinforced members the provisions of longitudinal tension and compression reinforcement inQ902 Q902 (web) and Q906 (stirrups) shall be modified by replacing fsk by the stress in the FRP reinforcementat

In order to assess the stress corresponding to this strain EFd shall be used

908 Requirements to minimum stirrup reinforcement may be waived for ribbed slabs with ribs in one or twodirections monolithically connected to a top slab The following requirements shall be satisfied

mdash the width of the ribs shall be at least 60 mm and the depth shall not exceed 3 times the minimum widthmdash clear distance between ribs shall not exceed 500 mmmdash the thickness of the top slab shall be at least 50 mm and shall have reinforcement at least equal to the

required minimum reinforcement for slabs

For ribbed slabs that do not satisfy these requirements the rules for beams shall apply

909 Compression reinforcement bars shall be braced by stirrups with spacing not exceeding 15 times thediameter of the compression reinforcement bar

Q 1000 Minimum area of reinforcement - columns

1001 The dimensions of columns shall be no less than

mdash 40 000 mm2 as gross cross-sectional areamdash 150 mm as minimum sectional dimension for reinforced columns

sk

tkcs f

fAA sdotsdotsdotge αsin20

mdash 200 mm as minimum sectional dimension for un-reinforced columns

1002 Steel reinforced columns shall not have less total cross-sectional area of longitudinal reinforcementthan the larger of

001 middot Ac and 02 middot Ac middot fcn fsk

1003 The minimum reinforcement shall be symmetrical The diameter of longitudinal reinforcement shall beno less than 10 mm If the column has a larger cross section than structurally required the minimumreinforcement may be determined by the structurally required cross section

1004 If the longitudinal reinforcement in the column is not extended into the structure below splicing barsshall be extended up into the column with a total area at least equal to the required reinforcement for thecolumn

1005 If bars at the top of a column are bent towards the centre to allow extension into a column with a smallersection located above the longitudinal inclination shall not exceed 16 and the point of bend shall be locatedminimum 100 mm above the column top

1006 If the area of longitudinal reinforcement is larger than 2 of the cross-sectional area of the columnlapped splicing at transverse bracings shall be limited to a fraction corresponding to 2 of the area of thecolumn Spliced and continuous bars shall be symmetrically distributed over the cross section of the column

1007 The position of the longitudinal reinforcement shall be secured by stirrups enclosing the reinforcementat a spacing not exceeding 15 times the diameter of the longitudinal reinforcement In addition the longitudinalreinforcement shall be secured at any points of the bend Required compressive reinforcement shall not belocated further away from corner of supporting transverse reinforcement stirrup or hook than 15 times thediameter of the supporting bar

1008 If concrete of grade C55 or higher is used the spacing of the links shall be reduced to 10 times thediameter of the longitudinal reinforcement and the stirrups shall be ribbed bars with diameter at least equal to10 mm

For FRP reinforced members stirrups shall be FRP bars with a diameter at least equal to 10 mm The amountof minimum stirrups (links) shall not be less than the provisions of stirrups in beams Q906 as modified byQ907

1009 In spiral reinforced columns the spiral shall be bent mechanically and shall have circular form insections perpendicular to the direction of the force The ascent per winding shall not exceed 17 of the corediameter The clear distance between spiral windings shall not exceed 60 mm nor be less than 35 mm Thespiral reinforcement shall extend through the entire length of the column and is only permitted to be omittedwhere the column is embedded in a reinforced concrete slab on all sides Splicing of spiral reinforcementbetween floors of concrete shall be performed as welded splices When terminating a spiral the spiral bar shallbe bent into the core and shall there be given an anchorage length at least equal to 25 times the diameter of thebar Plain bars shall in addition be terminated by a hook The base for a spiral reinforced column shall be madestrong enough to resist the increased stress in the core section If the force transfer is not secured in anotherway a sufficiently large transition spiral of height at least equal to the core diameter of the columns shall beplaced in the column base

Above requirements do not apply to FRP reinforced members The influence of spiral FRP bars on the ductilityand strength increase of columns requires further investigation

Q 1100 Minimum area of reinforcement - walls

1101 Steel reinforced walls shall have horizontal reinforcement with cross-sectional area corresponding to

for horizontal reinforcement in external walls

for internal walls horizontal and vertical reinforcement

for reinforcement in shell type structures in both directions

where ftk = defined in Q603

sk

tkcs f

fAA sdotsdotge 60

sk

tkcs f

fAA sdotsdotge 30

sk

tkcs f

fAA sdotsdotge 60

1102 In structures where strong limitations of the crack widths are required the horizontal reinforcementshould be at least twice the values given above The horizontal reinforcement may be reduced if the wall is freeto change its length in the horizontal direction and if it can be demonstrated by calculations that the chosenreinforcement can resist the forces caused by loads shrinkage and temperature changes with acceptable crackwidths The spacing between horizontal bars in same layer shall not exceed 300 mm

1103 The spacing between vertical bars in the same layer shall not exceed 300 mm At openings in walls inaddition to the minimum reinforcement given above at least 2 ribbed bars of 12 mm diameter shall be providedparallel to the edges or diagonally at the corners and the anchorage lengths to both sides shall be at least 40times the diameter of the bar

For FRP reinforced members FRP bars shall be used instead of ribbed bars The number and diameter of thebar shall account for the different EF for FRP reinforcement compared with steel reinforcement

1104 In walls which are primary exposed to bending caused by local pressure load the requirementsregarding minimum reinforcement in plates in accordance with Q700 shall apply

Q 1200 Minimum area of reinforcement - reinforced foundations

1201 Foundations shall have thickness no less than 10 times the diameter of the reinforcement bar or 200 mmwhichever is the smaller

1202 Tensile reinforcement at the bottom of a column foundation may be uniformly distributed over the fullwidth if the width does not exceed 5 times the diameter of the column measured in the same direction If thewidth of the foundation is larger 23 of the tension reinforcement shall be located within the middle half of thefoundation unless a more correct distribution is verified

1203 Foundations shall be considered as beams or slabs with respect to minimum reinforcement Referenceis made to Q700 Q800 and Q900

Q 1300 Minimum area of reinforcement - prestressed structures

1301 The structures shall be designed formed and constructed so that the deformations required accordingto the calculations are possible when applying the prestressing forces The influence of creep shall beconsidered when necessary

1302 At the anchorages the concrete dimensions shall be sufficient to ensure that a satisfactory introductionand transfer of the anchorage forces is obtained The documentation shall be based on calculations or tests forthe anchorage in question

1303 Directly inside anchorages for prestressed reinforcement extra reinforcement in the shape of a weldedwire fabric perpendicular to the direction of the force or a circular reinforcement should be provided If thestress in the contact surface between anchorage member and concrete exceeds fcd this shall be applied Thequantity of this extra reinforcement shall be documented by tests or calculations for the type of anchorage inquestion

R Corrosion Control

R 100 General

101 This section is not applicable for structures reinforced solely by FRP reinforcement

102 Requirements to corrosion protection arrangement and equipment are generally given in DNV-OS-C101Section 10 Special evaluations relevant for Offshore Concrete Structures are given herein

103 Fixed and floating concrete structures associated with production of oil and gas comprises permanentstructural components in Carbon-steel that require corrosion protection both topside and in shafts In additionshafts and caissons may contain mechanical systems such as piping for topside supply of seawater and forballast crude oil storage and export These piping systems are exposed to corrosive environments bothinternally and externally Riser and J-tubes may be routed within or outside shafts Drill shafts containconductors and support structures with large surface areas that are also to be protected from corrosion Internalcorrosion control of risers tubing and piping systems containing fluids other than seawater is however notcovered by this Standard

104 Steel rebars and prestressing tendons are to be adequately protected by the concrete itself ie providedwith adequate cover have due consideration paid to typequality of the aggregates and by setting limitationson crack widths in design However rebar portions freely exposed to seawater in case of concrete defectsembedment plates penetration sleeves and various supports will normally require corrosion protection

R 200 Corrosion zones and environmental parameters

201 A fixed concrete structure will encounter different types of marine corrosion environments These maybe divided into corrosion zones as given in Table R1

202 The splash zone is the external part of the structure being intermittently wetted by tidal and wave actionIntermediate zones include shafts and caissons that are intermittently wetted by seawater during tidal changesand dampened wave action or during movement of crude oilballast water interface level The externalinternalatmospheric zones and the submerged zones extend above and below the splashintermediate zonesrespectively The buried zone includes parts of the structure buried in seabed sediments or covered by disposedsolids externally or internally

203 The corrosivity of the corrosion zones varies as a function of geographical location temperature beingthe primary environmental parameter in all zones In the atmospheric zones the frequency and duration ofwetting (ldquotime-of-wetnessrdquo) is a major factor affecting corrosion In the external atmospheric zone thecorrosive conditions are typically most severe in areas sheltered from direct rainfall and sunlight but freelyexposed to sea-spray and condensation that facilitates accumulation of sea salts and moisture with a resultinghigh time-of-wetness A combination of high ambient temperature and ldquotime-of-wetnessrdquo creates the mostcorrosive conditions

204 In the atmospheric zones and the splashintermediate zones corrosion is primarily governed byatmospheric oxygen In the external submerged zone and the lower part of the splash zone corrosion is mostlyaffected by a relatively thick layer of marine growth Depending on the type of growth and the local conditionsthe net effect might be either to enhance or retard corrosion attack In the buried and internal submerged zones(ie seawater flooded compartments) oxygen in the seawater is mostly depleted by bacterial activitySimilarly steel surfaces in these zones and in the external submerged zone are mostly affected by biologicalgrowth that retards or fully prevents access of oxygen by diffusive mass transfer Although this could retardcorrosion corrosive metabolises from bacteria can offer an alternative corrosion mechanism

205 Corrosion governed by biologic activity (mostly bacteria) is referred to as MIC (microbiologicallyinfluenced corrosion) For most external surfaces exposed in the submerged and buried zones as well asinternal surfaces of piping for seawater and ballast water corrosion is primarily related to MIC

R 300 Forms of corrosion and associated corrosion rates

301 Corrosion damage to uncoated C-steel in the atmospheric zone and in the splashintermediate zonesassociated with oxygen attack is typically more or less uniform In the splash zone and the most corrosiveconditions for the external atmospheric zone (ie high time of wetness and high ambient temperature)corrosion rates can amount to 03 mm per year and for internally heated surfaces in the splash zone even muchhigher (up to of the order of 3 mm per year In more typical conditions for the external atmospheric zone andfor internal atmospheric zones the steady-state corrosion rate for C-steel (ie as uniform attack) is normallyaround 01 mm per year or lower In the submerged and buried zones corrosion is mostly governed by MICcausing colonies of corrosion pits Welds are often preferentially attacked Corrosion as uniform attack isunlikely to significantly exceed about 01 mm per year but the rate of pitting may be much higher 1 mm peryear and even more under conditions favouring high bacterial activity (eg ambient temperature of 20degC to40degC and access to organic material including crude oil)

302 In most cases the static load carrying capacity of large structural components is not jeopardized by MICdue to its localized form The same applies to the pressure containing capacity of piping systems HoweverMIC can readily cause leakage in piping by penetrating pits or initiate fatigue cracking of components subjectto cyclic loading

303 Galvanic interaction (ie metallic plus electrolytic coupling) of Carbon-steel to eg stainless steel orcopper base alloys may enhance the corrosion rates given in R301 On external surfaces in the submerged andburied zones galvanic corrosion is efficiently prevented by cathodic protection In the atmospheric andintermediate zones and internally in piping systems galvanic corrosion shall be prevented by avoiding metallicor electrolytic contact of non-compatible materials

304 Very high strength steels (fsk gt 1 200 MPa) and certain high strength aluminium nickel and copper alloysare sensitive to stress corrosion cracking in marine atmospheres If susceptible materials shall be used crackingshould be prevented by use of suitable coatings

R 400 Cathodic protection

401 For details of design of cathodic protection systems see DNV-OS-C101 Sec10 C ldquoCathodic Protectionrdquo

Table R1 Corrosion zonesExternal zones Internal zones

External atmospheric zoneSplash zoneExternal submerged zoneBuried zone

Internal atmospheric zonesIntermediate zonesInternal submerged zones

S Design of Fibre Reinforced Concrete Members

S 100 General101 Short fibres are added to the concrete in small quantities to increase the concrete tensile strength of theconcrete The fibres may be made from either steel or FRP The amount of fibre which can effectively be addedto the concrete to ensure good mixing and workability will depend on the type of fibre its length shape andconcrete properties (slump LWA normal weight concrete strength admixtures etc)102 The properties of the fibre reinforced concrete shall be documented for the actual mix The formulasgiven in this standard to determine the characteristic strength characteristic tensile strength Youngrsquos modulusshall be considered as guidelines only Reference is made to Sec4 D for material requirements 103 In this Section of the standard the impact of the increased tensile strength of concrete ftd is as follows

mdash Sub-section F ndash Shear strength In this chapter the combined concrete and fibre reinforced ftd may replaceftd for concrete on its own

mdash Sub-section H ndash General Design Method for Structural Members Subjected to in-plane Forces No changemdash Sub-section K ndash Bond Strength and Anchorage Failure ndash No change The plain concrete properties are used mdash Sub-section O ndash Serviceability Limit State No change The crack width calculations shall be calculated

based on the tensile strength of concrete not the increased tensile strength of the fibre reinforced concretemdash Sub-section P ndash Design by Testing Effect of sustain loading shall be evaluated in interpretation of the short

term test resultsmdash Sub-section Q ndash Rules for Detailing of Reinforcement No change The minimum reinforcement shall be

based on ftk of the concrete not the increase tensile strength of the fibre reinforced concrete

104 The impact on design by including fibres in the concrete in accordance with this standard is by replacingthe design tensile strength ftd in F200 by the modified ftd obtained for fibre reinforced concrete It shall bedocumented by tests on beams that the increased shear strength predicted by the above approach actually isachieved using same concrete type of fibres etc

T Design of Structural Members made of Grout

T 100 General101 Structural grout is normally used in members joining other structural members together The connectionmay be of the following types

mdash Type A Steel to steel connections (eg tubular joints pile sleeve connections and transition piece tomonopile connections)

mdash Type B Steel to concrete connections (eg connection of steel tubular shaft to a concrete foundationsupport structure)

mdash Type C Concrete to concrete connections (typically connecting concrete members using structural groutas compressionshear member in the joint)

mdash Type D Connecting two precast concrete elements with in-situ cast structural grout connection

102 The characteristic grout compression strength shall be determined from tests conducted on 150 mmdiameter by 300 mm high cylinders see Sec4 E and Sec4 F for more details The characteristic compressionstrength of the grout shall be converted to in-situ strength by the following formula (see Section 4)

fcn = fcckmiddot (1-fcck600)where

fcck = characteristic compression cylinder strength of the structural grout

103 The characteristic tensile strength ftk of the grout shall be determined based on laboratory testing SeeSec4 E and F for more details104 The characteristic tensile strength shall be converted to in-situ tensile strength for use in the designcalculations using the following formula (see Section 4)

ftn = ftk middot(1-(ftk25)06)where

ftk = characteristic direct tensile strength of the grout

105 The material factors to be used for the structural grout shall be according to C100 Table C1106 The design strength in compression and tension is found by dividing the in-situ strengths fcn ftn by therelevant material factorfcd = fcnγc

ftd = ftnγc

T 200 Design for strength in ULS and ALS

201 The design of the grouted connection in ULS and ALS shall be carried out by predicting the principalstress distribution in the grout presuming the grout to be cracked when the tensile stresses exceed the tensiledesign strength ftd for the grout

202 Assuming cracking means that an alternative load carrying mechanism shall be derived where no tensilestresses are carried by the grout

Guidance noteA truss analogy in accordance with F300 describes such a method Eg in a tubular connection the tubular membermay be considered to carry the tensile forces provided sufficient bond between the tubular steel member and the groutcan be documented

203 The compression capacity of the grout shall be determined based on the design compression strengthfcd as modified to fc2d by relevant clauses in H and I for principal compressive stresses with perpendicularprincipal tensile strains

Guidance noteGenerally the assumption that the grout carries no tension except for shear forces (requires equations defining shearcapacity for detail under design) means that the tensile forces caused by cracking have to be carried by alternativeload response paths The truss analogy is such an approach Hence two approaches are available either to documentthe shear capacity of the connection or presume that the grout carries no tension and prepare a load carrying model inaccordance with the truss analogy

It shall be noted that the location where grout is applied in most cases shall be considered as a region withdiscontinuity in geometry or loads and shall be designed in accordance with H and I Reference is especially made tothe limited compression stress fc2d which limits the principal compression strength when the principal tensile strainsare acting perpendicular to the direction of the principal compression

In the same way as a principal tensile strain reduces the compression capacity principal compression stresses willincrease the compression capacity The maximum strength increase in biaxial compression shall be 30

The maximum compressive strength under a triaxial state of stress is increased even more When the equation forstrength increase considers the compressive confining stresses σ2 and σ3 then both stresses σ2 and σ3 shall be equalin magnitude to obtain the full triaxial strength increase in the third direction If one of the stresses is zero then thestate of stress becomes biaxial

Confining pressure can result from internal stresses in the grout caused by response to external forces by friction dueto different material (load is transferred to grout through a steel plate) or by activation the tensile reinforcement in thegrout member (eg by steel reinforcement)

Generally confinement pressure in the grout created from tensile reinforcement shall be considered a passiveconfinement pressure Passive confinement pressures caused by equilibrium of stresses in the cross-section will inmost cases create a principal tensile strain perpendicular (causes the tensile stress in reinforcement) to the mainprincipal compression stress Accordingly the compression strength shall technically be reduced for this condition inaccordance with the compression field theory in H

T 300 Design for fatigue life

301 The design for fatigue life of the structural member made of grout (plain or fibre reinforced) shall becarried out in accordance with the general provisions in M

302 The design fatigue strength of the grout shall be derived as specified in T100 The factor C5 defining thedesign Woumlhler Curve for the grout in M200 shall be derived by experimental testing of the actual structuralgrout The value of C5 shall be documented in the Material Certificate for the Grout

Guidance noteWhen the principal stress axes rotate on load reversal the stress range may as a guideline be calculated based on theminimum numerical stress in the same direction as the maximum principal compressive stress (numerically largestcompressive stress) Compressive stress in the formula M200 is taken as positive When σmin is tensile then the stresscan be taken as zero in the Woumlhler Curve for the Grout in M200

It shall be noted that in M200 the compression force is positive and defined as the maximum stress while theminimum stress on load reversal is defined as σmin in the same direction of the max principal compression directionIf the stress on load reversal above defined as σmin then σmin may be taken as zero

303 In regions with discontinuity in geometry or loads ie in areas where I applies for design of concretestructures the same design principal applies for grouted members The fatigue reference strength shall be takenin accordance with T302

T 400 FE Analyses of grouted connections

401 Non-linear FE analyses may be used in determining the stress situation in the groutGuidance noteA non-linear FEM may differ from case to case However the following general principles are considered important

- The boundary conditions in the model shall be representative - Representative boundary conditions also mean that slippage and contact element shall be used to ensure that tensile

stresses are not transferred beyond its tensilefriction capacity- In order to obtain reliable design results the tensile stresses in the FEM shall not exceed the design tensile strength

of the grout ftd It shall be noted that material factors shall be included in defining the material strength used in theFE model when design capacity is determined by the FE analysis

- For a stress situation with combined tension-compression the compression stress shall not exceed fc2d defined inChapter H as part of the compression field theory In non-linear FE analyses this is also covered by acomprehensive biaxial and triaxial failure envelope The failure envelope shall be realistic and shown to be so bycomparing with outputs with experimental test results

- A failure envelope which considers strength increase due to biaxial and triaxial state of stress is acceptable but thestrength increase shall be documented taking into account the principal stresses in the grout in the other directionsThe increased strength shall in general be related to fcd as the basic uniaxial strength of the grout

In most analysis the failure occurs when the compression stress reaches the compressive strength provided tensilestresses in the grout have been transferred to adjacent steel members If tensile failure occurs either by cracking(unable to transfer the tensile stresses to nearby steel member) or by boundary slippage then instability of the non-linear analyses may occur suddenly This is a general sign of failure Non- linear analyses may be sensitive to failure of for example small pieces of grout from the structural member If suchfailures are encountered in the analytical FE model then instability of the analyses will be noted In some cases this maybe the failure load and in other cases the model will still have remaining capacity but observes instability in the iterations

T 500 Fibre reinforced grout501 The design of fibre reinforced grouted members shall be designed following the principles describedabove The only difference is that the tensile strength ftd is increased In this way the structural member cancarry more load prior to tensile cracking The increased ftd shall be included in the design calculations

T 600 Type A steel to steel connections with grout601 This may describe typical pile sleeve connection or grouted connections between tubular members Thediameter change between the inner and outer tubular members with grout in between will initiate compressionstresses in the grout The magnitude of these compression stresses depends on the diameters and thicknessesof the connecting members

602 The capacity both in ULS and FLS depends on the surface roughness the diameter of the tubular jointas well as the thickness and strength of the steel and grout elements

Guidance noteFor a detailed design approach for the design of grouted tubular monopile connections see DNV-OS-J101

603 The structural connection may be designed with shear keys mounted on the tubular sections The shearkeys may be welds on both tubular members to be joined together

604 The connection shall be designed taking into account the material and geometric properties of the groutas well as those of the shear keys

Guidance noteThe shear keys may be designed in accordance with A500 The grout design strength fcd should be in accordance withC100 as modified by I105 to 107 The strength may be evaluated using a truss model in which the capacity is providedby principal compression stresses The strength of the compression strut is limited by fc2d as provided in I107 due totensile strains perpendicular to the compressive strength under investigations

605 The grout material shall be documented in accordance with requirements in Sec4 E and Sec4 F Theproperties of the grout shall be documented in a Material Certificate see Appendix H

Guidance noteIn fatigue life predictions according to M frd shall be replaced with fc2d The compression stress under considerationshall be computed in the main compression direction for the major load response in the joint For simplicity no rotationof the principal axis is assumed

The contact pressure between the shear keys if applicable and the grout shall also be checked for fatigue lifeIf the grouted connection is submerged in water in splash zone or if rain water may accumulate inon the connectionthen pumping action may occur due to the dynamic behaviour of the structure and the joint hence the factor C1 forfatigue strength evaluation shall be taken as 8 for submerged concrete presuming cracking

T 700 Type B steel to concrete connection

701 This often describes a connection in which the steel support plate of a steel structure is connected to a concretestructure For mounting and aligning purposes the volume between the steel flange and the concrete member is filledwith structural grout to transfer the load The layer of grout has in most cases a limited thickness The force throughthe grout will be transferred into the concrete member as a partially loaded area see L702 The static strength in ULS of the structural grout will increase due to restrain by the steel flange hencethe design strength in ULS may be increased with a factor

Guidance noteThe maximum restraint from the steel plate under static load may be taken as 12 (eg the ratio between a concretecube test and the cylinder strength) The cube strength is known to be affect by the restraining effect of the steel plateThe grout is considered as unreinforced and the material factors in C100 apply

703 The strength under fatigue loading may also be affected by the friction but the friction effects may bereduced under fatigue loading If water can assemble and wet the grout then the factor C1 = 10 on the Woumlhlercurves in M200 applies

Guidance noteUntil more data is available the fatigue strength of the structural grout and the fibre reinforced grout shall be takenas defined in Sec4 E and Sec4 F with no strength increase due to confinement The grout is considered to beunreinforced with the material factors for unreinforced grout defined in C102

704 The local strength under the load application point during fatigue loading may also be affected by theload spreading according to L The magnitude of this influence is currently not known If water can assembleand wet the concrete then the factor C1 = 10 on the Woumlhler curves in M200 applies

Guidance noteUntil more data is available the increase in fatigue strength of the concrete and grout (depending on geometry of theconnection) due to confinement in partially loaded areas shall be limited to a factor of 13 and the material factors inC102 shall apply

T 800 Type C concrete to concrete connection

801 This often describes a connection in which two concrete structural elements are connected together Formounting and aligning purposes the volume between the elements is filled with structural grout to transfer theload The layer of grout has in most cases a limited thickness The force through the grout will be transferred intothe concrete member as a partially loaded area see L

802 As the Poissonrsquos ratio and the Youngrsquos modulus of concrete and grout are of the same order ofmagnitude no additional restraint from the interface between grout and concrete shall be considered in designstrength in ULS

Guidance noteReinforcement perpendicular to the load action will partly restraint the concrete This confinement is dependent ontensile strains perpendicular to the principal compression direction in order to be activated Technically theprovisions of H100 and I100 apply for this condition The confining action of the reinforcement and the compressivestrength reductions in accordance with H100 and I100 are considered to oppose each other when transversereinforcement perpendicular to the load direction is included hence no strength increase The concrete is reinforcedand the material factors in C102 apply

T 900 Type D connecting two precast concrete elements with in-situ cast structural grout connection 901 This often describes a connection in which a concrete precast element is connected to another precastconcrete element through an in-situ cast grout 902 The grouted connection shall be reinforced by steel reinforcement from both connected precast elements

Guidance noteFor concrete pre-cast tower structures subject to alternating bending moments compression in the groutedconnections should be maintained by the use of a post tensioning system

903 As the Poissonrsquos ratio and Youngrsquos modulus of concrete and grout is of the same order of magnitude noadditional restraint from the interface between grout and concrete shall be considered in design strength in ULSfor the grout

Guidance noteReinforcement perpendicular to the load may partly restraint the concrete This confinement is dependent on tensilestrains perpendicular to the principal compression direction in order to be activated Technically the provisions ofH100 and I100 also apply for this condition The confining action of the reinforcement and the compressive strengthreductions in accordance with H100 and I100 are considered to oppose each other when transverse reinforcementperpendicular to the load direction is included hence no strength increase The grout is reinforced and the materialfactors in C102 apply

904 For fatigue assessment due consideration shall be taken of water in or on the grout surface as well as theinteraction of the grout with adjacent surfaces

Guidance noteFor design of the grout under fatigue loading no local strength increase shall be implemented in the fatigue designstrength If water can assemble and wet the concrete then the factor C1 = 10 on the Woumlhler curves in M200 appliesIf the interface between the grout and the concrete may be exposed to stress variations between tensile stress andcompressive stress and the grout is exposed to rainwater or otherwise exposed to water which may assemble the factorC1= 8 on the Woumlhler curves in M200 applies

SECTION 7CONSTRUCTION

A General

A 100 Application101 This Section applies to the fabrication and construction of reinforced and prestressed concrete structuresand structural parts or assemblies in concrete or grout102 Fabrication and construction of assemblies not adequately covered by this Standard shall be speciallyconsidered

A 200 Codes and standards201 Codes and Standards other than those stated within this Standard may be accepted as an alternative oras a supplement to these Standards The basis for such acceptance is stated in Section 1

A 300 Scope301 The requirements of this section apply to material testing formwork reinforcement concreteproduction concrete coating prestressing systems and repairs during construction of concrete structures

B Definitions

B 100 Terms101 In the context of this Standard the term ldquofabrication and constructionrdquo is intended to cover fabricationand construction workings from initial fabrication to end of design life of the installation or component thereofas applicable102 The term Site used within the context of this Standard shall be defined as the place of construction of theconcrete structure (placing of reinforcement formwork assembly and pouring of concrete into the formworksor assembling of precast concrete units)

C Documentation

C 100 General101 As the basis for fabrication and construction activities the following documentation as applicable shallbe approved explicitly by the designer and other relevant parties ldquofor constructionrdquo

mdash drawings showing structural arrangement and dimensions with specifications and data defining all relevantmaterial properties

mdash relevant fabrication and construction specificationsmdash details of welded attachmentsconnectionsmdash drawings and description of the reinforcement and prestressing systemmdash requirements to extent qualification and results of fabrication and construction inspection testing and

examination proceduresmdash specifications for the corrosion protection systemsmdash any limitationstolerances applicable as a result of design assumptions

102 Assumptions made during the design of the structure influencing the fabrication and constructionactivities shall be documented and shall be realistic in respect of allowing a safe construction process Designand Construction Risk Assessments may be required to achieve this103 Relevant documentation from the fabrication and construction required for safe operation of the structureshall be readily available on the InstallationSuch documentation shall give sufficient information to evaluate damages and subsequent possible repairs andmodifications

D Quality Control - Inspection Testing and Corrective Actions

D 100 General101 Supervision and inspection shall ensure that the works are completed in accordance with this Standardand the provisions of the project specification

102 Quality assurance and quality control A quality management system based on the requirements of ENISO 9001 shall be applied to the following phases

mdash organisationmdash design and procurementmdash equipment shop manufacturemdash equipment storage and transportmdash construction (ie earthworks construction towing installation backfilling civil works and structural

steelwork storage tanks pressure vessels separators furnaces boilers pumps above ground pipingincluding supports underground piping instrumentation electricity cathodic protection paint workthermal insulation fire proofing etc) The content in brackets will vary dependent on the actual structureplant under construction

A specific quality control programme including inspection and tests shall be set up to monitor the qualitythroughout the different phases of the design fabrication and construction

D 200 Inspection Classes

201 In order to differentiate the requirements for inspection according to the type and use of the structurethis Standard defines three inspection classes

IC 1 Simplified inspectionIC 2 Normal inspectionIC 3 Extended inspection

202 The inspection class to be used shall be stated in the project specification

203 Inspection class may refer to the complete structure to certain members of the structure or to certainoperations of execution

204 In general inspection class 3 ldquoExtended inspectionrdquo applies for Offshore Concrete StructuresInspection class 1 ldquoSimplified inspectionrdquo shall not be used for concrete works of structural importance

D 300 Inspection of materials and products

301 Inspection shall be witnessed and signed by a qualified department different from the productiondepartment

302 The inspection of the properties of the materials and products to be used in the works shall be as givenin Table D1

303 In addition FRP reinforcement shall be inspected to verify that the bars show no visible signs of handlingdamage

304 The FRP bars shall be adequately marked for identification upon arrival The marking shall bemaintained to establish traceability until actual use in the structure

305 FRP reinforcement shall be stored in a manner which prevents harmful exposure to UV light and erasureof marking Reinforcement of different grades and dimensions shall be stored separately

D 400 Inspection of execution

401 General

Inspection of execution according to this Standard shall be carried out as given in Table D2 unless otherwisestated in the project specification

Table D1 Inspection of materials and productsSubject Inspection Class 1

SimplifiedInspection Class 2

NormalInspection Class 3

ExtendedMaterials for formwork Not required In accordance with project specificationReinforcing steel In accordance with ISO 6935 and relevant national standardsPrestressing steel Not applicable In accordance with ISO 6934FRP reinforcement In accordance with Material CertificatePrestressing FRP reinforcement

In accordance with Material Certificate

Fresh concrete ready mixed or site mixed

In accordance with this Standard

Other items 1) In accordance with project specification and this standardPrecast elements In accordance with this StandardInspection report Not required In accordance with this Standard1) Could be items such as embedded steel components

402 Inspection of falsework and formwork

Before casting operations start inspections according to the relevant inspection class shall include

mdash geometry of formworkmdash stability of formwork and falsework and their foundationsmdash tightness of formwork and its partsmdash removal of detritus such as saw dust snow andor ice and remains of tie wire and debris from the formwork

etc from the section to be castmdash treatment of the faces of the construction jointsmdash wetting of formwork andor basemdash preparation of the surface of the formworkmdash openings and blockouts

The structure shall be checked after formwork removal to ensure that temporary inserts have been removed

403 Inspection of reinforcement

Before casting operations start inspections according to the relevant inspection class shall confirm that

Reinforcement is not contaminated by oil grease paint or other deleterious substances

mdash The reinforcement shown on the drawings is in place at the specified spacingmdash The cover is in accordance with the specificationsmdash Reinforcement is properly tied and secured against displacement during concretingmdash Space between bars is sufficient to place and compact the concrete

After concreting the starter bars at construction joints shall be checked to ensure that they are correctly locatedFor structures of Inspection Class 2 and 3 all FRP bars shall be inspected before concreting Materials shall beidentified by appropriate documentation as specified in Sec4 I

404 Inspection of prestressing works

Before casting operations start inspections shall verify

mdash The position of the tendons sheaths vents drains anchorages and couplers in respect of design drawings(including the concrete cover and the spacing of tendons)

mdash The fixture of the tendons and sheath also against buoyancy and the stability of their supportsmdash That the sheath vents anchorages couplers and their sealing are tight and undamagedmdash That the tendons anchorages andor couplers are not corrodedmdash The cleanliness of the sheath anchorages and couplers

Prior to tensioning or prior to releasing the pretension force the actual concrete strength shall be checkedagainst the strength required The relevant documents and equipment according to the tensioning programmeshall be available on site The calibration of the jacks shall be checked Calibration shall also be performedduring the stressing period if relevant

Table D2 Inspection of executionSubject Inspection Class 1 Inspection Class 2 Inspection Class 3

Scaffolding formwork and falsework

Random checking Major scaffolding and formwork to be inspected before concreting

All scaffolding and formwork shall be inspected before concreting

Reinforcement (steel and FRP)

Random checking Major reinforcement shall be inspected before concreting

All reinforcement shall be inspected before concreting

Prestressing reinforcement (steel and FRP)

NA All prestressing components shall be inspected before concreting threading stressing Materials to be identified by appropriate documentation

Embedded items According to project specificationErection of precast elements NA Prior to and at completion of erectionSite transport and casting of concrete

Occasional checks Basic and random inspection Detailed inspection of entire process

Curing and finishing of concrete

Occasional checks Occasional checks Regular inspection

Stressing and grouting of prestressing reinforcement

NA Detailed inspection of entire process including evacuation of stressing records prior to cutting permission

As-built geometry NA According to project specificationDocumentation of inspection

NA Required

Before grouting starts the inspection shall include

mdash preparationqualification tests for groutmdash the results of any trial grouting on representative ductsmdash ducts open for grout through their full length and free of harmful materials eg water and icemdash vents prepared and identifiedmdash materials are batched and sufficient to allow for overflow

During grouting the inspection shall include

mdash conformity of the fresh grout tests eg fluidity and segregationmdash the characteristics of the equipment and of the groutmdash the actual pressures during groutingmdash order of blowing and washing operationsmdash precautions to keep ducts clearmdash order of grouting operationsmdash actions in the event of incidents and harmful climatic conditionsmdash the location and details of any re-injection

405 Inspection of the concreting operationsThe inspection and testing of concreting operations shall be planned performed and documented in accordancewith the inspection class as shown in Table D3The inspection class for concreting operations shall be Inspection Class 3 unless otherwise specified in theproject specificationDifferent structural parts in a project may be allocated to different inspection classes depending on thecomplexity and the importance in the completed structure

406 Inspection of precast concrete elementsWhen precast concrete elements are used inspection shall include

mdash Visual inspection of the element at arrival at sitemdash Delivery documentationmdash Conditions of the element prior to installationmdash Conditions at the place of installation eg supportsmdash Conditions of element any protruding rebars connection details position of the element etc prior to

joining and execution of other completion works

407 Actions in the event of a non-conformityWhere inspection reveals a non-conformity appropriate action shall be taken to ensure that the structureremains fit for its intended purpose As part of this the following should be investigated

mdash Implications of the non-conformity on the execution and the work procedures being appliedmdash Implications of the non-conformity on the structure safety and functional abilitymdash Measures necessary to make the element acceptablemdash Necessity of rejection and replacement of non-conforming elements

Documentation of the procedure and materials to be used shall be approved before repair or corrections aremade

E Construction Planning

E 100 General101 Prior to construction procedures for execution and control of all construction activities shall be preparedin order to ensure that the required quality is obtained and documented

Table D3 Requirements for planning inspection and documentationSubject Inspection

Class 1Inspection

Class 2Inspection

Class 3Planning of inspection NA Inspection plan procedures and work instructions program

Actions in the event of non-conformities

Inspection NA Frequent but random inspection

Continuous inspection of each casting

Documentation NAAll planning documentsRecords from all inspectionsAll non-conformities and corrective action reports

102 Procedures detailing the construction sequences testing and inspection activities shall be preparedSufficient delivery of materials and storage capacity shall be ensured to accommodate the anticipated demandfor any continuous period of casting

103 The planning for all construction stages shall ensure that there is adequate time for the concrete to hardensufficiently to support the loads imposed

104 Due consideration shall be given to access and time required for adequate survey and inspection as theconstruction proceeds

105 Constructional operations concerning transportation and installation operations shall be detailed inspecial procedures prepared in accordance with the requirements given in Section 3

106 For FRP reinforced structures special care in the construction planning is required because all bars aredelivered in its final shape and dimensions to the construction site Only the straight bars can be modified atsite in this case by reducing the length The bars cannot generally be bent welded etc at the construction sitewhen installing the bars in the casting forms For complex structural members special planning not normally carried out in construction should be required

F Materials and Material Testing

F 100 General

101 Constituent materials reinforcement and prestressing systems used in construction as well as fresh andhardened concrete and grout shall satisfy the relevant requirements given in Section 4

102 Testing of materials shall be performed prior to and during construction to confirm quality of thematerials and to ensure that the specified properties are obtained

103 Testing of materials shall be performed in accordance with the requirements of Section 4 The testingshall be conducted with calibrated and tested instruments and equipment

104 Testing at independent recognized laboratories may be required105 Records of all performed testing shall be kept for later inclusion in the Construction Records

F 200 Constituent Materials201 Storage and handling of constituent materials shall be in accordance with recognized good practice Thematerials shall be protected from detrimental influences from the environment202 Cement shall be delivered with Workrsquos Certificate (mill certificate) in accordance with Section 4Different batches of cement are as far as practicable to be stored in different silos such that the results of theon-site testing can be referred to specific batches

203 Testing of cement on site shall be performed on a random basis during the construction period Thefrequency of the sampling shall be specified based on experience and shall be approved by clientverificationauthority prior to start of construction The sampling shall be representative for the delivered cement Anincreased frequency of sampling may be required in the following cases

a) Change of supplier

b) Change of typegradec) Change of requirements to concrete properties

d) Unsatisfactory test results

e) Unsatisfactory storage conditionsf) Other information or events that may justify an increased sampling

204 Testing of cement is at least to be performed to establish the following properties

mdash finenessmdash initial and final setmdash oxide compositionmdash mortar strength

Testing shall be performed as specified in Section 4 and the test results shall satisfy the requirements inSection 4 Cement failing to meet the requirements shall not be used205 Aggregates shall be tested upon delivery at site If different sources of aggregates are used the propertiesshall be established for each source The following properties shall be established

mdash particle size distribution (grading) including silt contentmdash content of organic matter

mdash density and specific gravitymdash strength in standard mix of concrete and mortarmdash petro-graphical composition and properties that may affect the durability of the concretemdash water content

206 Aggregates delivered to the site shall be stored separately and such that the aggregates are protected fromaccumulation of water and other harmful influences of the environment and have markings identifying theircontents

207 Testing of aggregates shall be performed on a regular basis during the construction period The frequencyof the sampling shall be specified based on the quality and consistency of the supply as well the concreteproduction volume and shall be approved prior to start of construction An increase in the test frequency maybe required when tests are not giving satisfactory results upon ldquoa change of supplierrdquo or if changes in theuniformity of the supply are observed

208 The water source(s) shall be investigated for the suitability and dependability of the water supply Thewater shall not contain organic impurities detrimental salts or other matter that may have harmful or adverseeffects on fresh or hardened concrete as well as reinforcement The supply shall be sufficient and dependableenough to ensure adequate supply during any foreseen extensive production period

209 The quality of mixing water shall be documented by testing at intervals adjusted in each case to type ofwater supply (public or other) as agreed between the relevant parties

210 Admixtures delivered to a site for mix shall be furnished with test reports confirming the specifiedproperties Handling and storage of admixtures shall be in accordance with the suppliers recommendations

211 The effect of the admixtures on concrete shall be tested at intervals on site in terms of the followingproperties

mdash consistence eg at 5 and 30 minutes after mixing mdash water requirement for a given consistencemdash shrinkageswellingmdash strength in compression and tension (bending) at 7 28 and 91 days

F 300 Reinforcement and prestressing system components

301 All reinforcement shall be delivered to the construction site with appropriate certificates confirmingcompliance with the specified requirements (see Section 4) The steel shall be adequately marked for identificationupon arrival The marking shall be maintained to establish traceability until actual use in the structure

302 Reinforcement shall be stored in a manner which prevents harmful corrosion and erasure of markingReinforcement of different grades and dimensions shall be stored separately

303 Components of the prestressing system shall be delivered with appropriate certificates confirmingcompliance with the specified requirements (see Section 4) The marking shall be maintained to establishtraceability until actual use in the structure

304 Components for prestressing systems including cables shall be stored in a dry environment without anydanger of harmful corrosion They shall be given additional protection with water soluble protective oil Theoil shall be documented not to adversely affect the bond to the grout Alternately the cables shall be cleanedprior to use

305 Regular spot checks shall be performed on site to ensure

mdash Proper traceability marking and stocking of reinforcement and components of prestressing systemmdash That bending of bars is performed within approved diameters and temperatures

306 Procedures for welding of reinforcement steel and welders qualification are documented in accordancewith the requirements of Section 4

All welds shall be 100 visual examined Samples of welding shall be taken and tested at regular intervalsComprehensive documentation may be required by the clientverification authorities for critical welds

307 Testing of mechanical splices in reinforcement shall comprise

mdash Prior to construction 3 tensile tests of the splicesmdash During construction tensile tests of 1 of all splices performed

308 Testing of prestressing steel shall be performed at regular intervals prior to its use The intervals shall bepart of the procedure and the result of the testing shall be documented

309 Testing of components for the prestressing system and testing and calibration of stressing equipment maybe required and shall be documented

310 Testing of components for the FRP Prestressing system shall be performed at regular intervals prior toits use The intervals shall be part of the procedure and the testing shall be documented

F 400 Production and on-site quality control testing

401 Prior to start of construction the properties of the intended concrete mix shall be verified by testing ofsamples from a series of trial mixes The testing and test method shall be in accordance with the requirementsof Section 4

402 The following properties shall be documented

mdash mix proportions and the resulting consistence bleeding and air contentmdash compressive strengthmdash setting times and strength developmentmdash Youngrsquos modulus in compressionmdash permeability of hardened concretemdash durability in accordance with the approved specification requirementsmdash effect of admixtures

403 During production the concrete shall be tested regularly for strength air content consistencytemperature and density as given in Table F1

Each sample for strength testing taken from one batch at the form after transportation shall comprise of at least4 test specimens unambiguously marked for identification The collection curing and testing shall beperformed in accordance with an approved specification

404 Until the uniformity of a concrete has been demonstrated higher rates of testing may be required Duringcontinuous production rates of testing may be reduced as agreed with parties involved

405 The properties of a grout shall be tested through on-site quality controls at regular intervals during theproduction and placement of the grout

406 Records shall be kept of all testing including references to mix design date and time of sampling as wellas identify sectionsparts which were grouted

407 The frequency of on-site QC testing of neat cement grout shall be as a minimum as given in Table F2

In the case of extremely large volume pours the frequency of sampling for compressive strength may bereduced after agreement with the Society

408 The frequency of onsite QC testing of pre-pack blended grout shall be as a minimum as given in TableF3

409 Until uniform quality of the grout has been demonstrated higher frequencies of testing may be required

Table F1 Frequency of production testing of concreteParameter Frequency

Strength One sample per shift and normally not less than one sample for every commenced 100 m3 or at least one sample per change of constituent materials or mix proportion whichever gives the largest number of samples

Air content Temperature and consistency

Three times per shift or whenever a strength sample is taken

Density Once per shift

Table F2 Frequency of QC testing of Neat Cement GroutParameter Frequency

Compressive Strength Five test specimens shall be taken once per shift for every commenced 100 m3 once per change of constituent materials or mix proportion or for each compartment to be grouted whichever gives the largest number of tests

Expansion and bleeding Once per strength test or every 3 hoursViscosity Once per strength test or every 3 hoursDensity Once per strength test or every 3 hoursTemperature Once per strength test or every 3 hours

Table F3 Frequency of QC testing of Pre-packed Blended GroutParameter Frequency

Compressive Strength Five test specimens shall be taken once per shift for every commenced 100 m3 or for each compartment to be grouted whichever gives the largest number of tests

Bleedinghomogeneity (visual inspection)

Once per strength test or every 3 hours

Spread of flow Once per strength test or every 3 hours

Temperature Once per strength test or every 3 hours

410 Testing of grout shall be performed on specimens taken from samples collected during grout productionThe collection curing and testing shall be performed in accordance with an approved specification411 Samples for testing of fresh and hardened grout shall be whenever possible collected from evacuationpoints of the compartments being grouted and the samples taken from the emerging surplus grout

F 500 Testing of concrete in the structure501 The quality of the concrete in the structure may be required verified by tests of sawn drilled or in-situcast cores from the structure or by non-destructive examination The extent location and methods of suchtesting shall be agreed upon by clientverification authority in each case Increased examination of concrete inthe structure shall be considered if one of the following conditions occurs

mdash Standard strength test specimens indicate abnormally low strengthmdash The concrete has visible signs of inferior qualitymdash The concrete has been subjected to chemical attack or firemdash The concrete during curing has been exposed to freezing or premature drying outmdash Inadequate compaction curing or other unfavourable conditions are observed or suspected

502 The procedures to be followed together with calibration methods and criteria for non-destructiveexamination shall be approved in each case503 When test results are compared a relationship shall be established between the results from standardspecimens tested in accordance with the approved specification and the results of the additional testing of theconcrete in the structure

F 600 Non-cementitious materials601 Non-cementitious materials are materials such as epoxies and polyurethanes which are specially madefor use in combination with structural concrete to either improve the concrete properties or supplement repairor replace the concrete602 Non-cementitious materials shall be delivered with test reports specifying the composition and propertiesof the material The material shall be handled and stored in accordance with the suppliers recommendations603 Non-cementitious materials shall not be used unless a careful evaluation and testing has been performedprior to their use and procedures for the useapplication have been approved

G Formwork

G 100 Design materials and erection101 Falsework and formwork including their supports and foundations shall be designed and constructed sothat they are

mdash Capable of resisting any actions expected during the construction processmdash Stiff enough to ensure that the tolerances specified for the structure are satisfied and the integrity of the

structural member is not affected

Form function appearance and durability of the permanent structure shall not be impaired due to falseworkand formwork or their removal102 Formwork shall have sufficient strength stiffness and dimensional stability to withstand the loadingsfrom casting compaction and vibration of fresh concrete When casting concrete against non-vertical andnearly vertical formwork faces the pressure from wet concrete can cause significant uplift and shall be takeninto consideration In addition the support conditions for the formwork and possible live and environmentalloads prior to during and after the casting shall be considered103 For special and critical casting operations it may be required to submit design calculations for theformwork for advance approval104 Special care shall be taken when designing formwork for concrete with long setting time where largeheights of fresh concrete may exert significant loading on the formwork105 Slip-forming operations shall be described in a slip-forming procedure The procedure shall containstructural design jacking arrangement power supply method for dimensional control criteria for lifting andemergency procedures in case of stoppage106 Feasibility tests on site may be required for complicated slip-form operations107 Slip-forms with variable dimensions shall be specially considered108 Materials for formwork shall accommodate the requirements to strength stiffness and low waterabsorption Formwork shall be erected by experienced personnel working in accordance with detaileddrawings Wooden spacers shall not be used

109 Any material that leads to the fulfilment of the criteria given for the structure may be used for formworkand falsework The materials shall comply with relevant product standards where such exist Properties of thespecific materials such as shrinkage shall be taken into account if they can affect the end product110 The materials employed shall be consistent with any special requirements for the surface finish or latersurface treatment111 The method statement shall describe the method of erection and dismantling of temporary structures Themethod statement shall specify the requirements for handling adjusting intentional pre-cambering loadingunkeying striking and dismantling112 Deformations of formwork during and after concreting shall be limited to prevent deleterious crackingin the young concrete This may be achieved by limiting the deformations and by organizing the castingoperations in a manner such as to avoid harmful deformations113 Formwork shall keep the concrete in its required shape until it is hardened114 Formwork and the joints between boards or panels shall be sufficiently tight against loss of water andfines115 Formwork that absorbs moisture or facilitate evaporation shall be suitably wetted to minimize water lossfrom the concrete unless the formwork was designed specifically for that purpose116 The internal surface of the formwork shall be clean When slip-forming is used the form panels shall bethoroughly cleaned and a grease-like mould-release agent shall be applied prior to assembling of the form117 Special care shall be taken when designing formwork for concrete with high or altered flowcharacteristics where the hydrostatic pressure from concrete may be more than expected from normal concrete

G 200 Slip-form systems201 When using the slip-forming method the design and erection of the form and the preparation of theworks shall take into account the difficulties controlling the geometry and the stiffness of the entire workingplatform The entire slip-form structure shall be designed with the appropriate stiffness and strength Dueaccount shall be taken of friction against hardening concrete weight of materials stored on the form systemsfor adjusting geometry such as diameter wall thickness as well as climatic conditions to be expected duringthe slip-forming period202 The lifting capacity of the jacks shall be adequate The climbing rods shall be sufficiently strong not tobuckle Normally the climbing rods are left totally encased within the concrete If the climbing rods shall beremoved the holes thus left in the concrete shall be properly filled with grout via grouting inlets at the bottomor by injection hoses threaded in from the top The grout consumption shall be monitored to confirm completefilling203 The materials applied in the form may be either steel or wood and shall comply with the requirementsfor formwork materials The form shall have a height and batter consistent with the concrete to be used Theslip-forming rate and other conditions affecting the hardening process of the concrete shall be such as to reduceor eliminate the tendency for lifting cracks204 The slip-form shall have a hanging platform below the main form giving access for application of curingas well as inspection and if necessary light repair of the hardening concrete when appearing from under theslip-form205 The concrete cover to the reinforcement shall be kept within the tolerances using sufficiently long andstiff steel guides between the reinforcement and the form adequately distributed around the form206 There shall be contingency plans prepared for unintended situations such as break-down in concretesupply problems with the lifting devices hardening of the concrete etc

G 300 Jump-forming systems301 Jump-forming systems when used shall have adequate strength and stiffness for all loads exerted duringthe erection and casting period There shall be a robust system for support of the forms in the previously castconcrete Inserts for support shall be approved for the actual application302 The jump-form when installed shall allow the necessary preparation and cleaning of construction jointsThe jump-form system shall accommodate the necessary walkways and access platforms to ensure that theconcreting works can be performed in an appropriate manner

G 400 Inserts in formwork recesses and blockouts401 Temporary inserts to keep the formwork in place bars ducts and similar items to be cast within thesection and embedded components eg anchor plates anchor bolts etc shall

mdash Be fixed robustly enough to ensure that they will keep their prescribed position during placing andconcreting

mdash Not introduce unacceptable loading on the structuremdash Not react harmfully with the concrete the reinforcement or prestressing steel

mdash Not produce unacceptable surface blemishesmdash Not impair functional performance tightness and durability of the structural membermdash Not prevent adequate placing and compaction of the fresh concrete

402 Any embedded item shall have sufficient strength and stiffness to preserve its shape during theconcreting operation and be free of contaminates that would affect them the concrete or the reinforcement403 Recesses used for temporary works shall be filled and finished with a material of similar quality as thesurrounding concrete unless it is otherwise specified Block-outs and temporary holes shall generally cast withnormal concrete Their surfaces shall be keyed or slanted and prepared as construction joints

G 500 Removal of formwork and falsework501 Falsework and formwork shall not be removed until the concrete has gained sufficient strength to

mdash Resist damage to surfaces that may arise during the strikingmdash Take the actions imposed on the concrete member at that stagemdash Avoid deflections beyond the specified tolerances due to elastic and inelastic (creep) behaviour of the concrete

502 Striking shall be made in a manner that will not subject the structure to overload or damage503 Propping or re-propping may be used to reduce the effects of the initial loading subsequent loading andor to avoid excessive deflections Propping may be required in order to achieve to intended structural behaviourof members cast in two or more casting operations504 If formwork is part of the curing system the time of its removal shall take into account the requirements J300

G 600 Surface treatment and final preparation601 At completion of formwork erection and during slip-forming operations it shall be ensured that theformwork is free of all foreign matter that casting joints are prepared and treated as specified and that theformwork is given appropriate surface treatment602 Formwork with permanent low-adhesion coating may be used Form release agents used shall besatisfactorily documented not to be detrimental to the bond between reinforcement and concrete603 The surface treatment and final preparation of formwork shall be described in a special procedure604 Release agents shall neither be harmful to the concrete nor shall they be applied in a manner that willaffect the concrete the reinforcement or the bond between the twoRelease agents shall not have a detrimental effect on the surface finish or subsequent coatings if any Releaseagents shall be applied in accordance with the manufacturers specification605 Dimensional control during and after completion of the formwork is as a minimum to include

mdash Geometry and dimensions of cross sectionsmdash Overall geometry including deviation from theoretical shape and out of alignment

H Reinforcement and Embedded Steel

H 100 Reinforcement101 Reinforcement shall be of the type grade and dimensions given in the approved specification drawings(see also requirements in Section 4) and shall be placed with the spacing splices and concrete covers stated inthe same documents102 The surface of the reinforcement shall be free of substances that may be harmful to the reinforcement orthe bond between reinforcement and concrete at the time of installation and shall be protected from suchsubstances until casting of concrete commences103 Steel reinforcement is normally to be cold bent to the required shape in one operation Hot- or rebendingis only allowed upon special agreement Bending shall be done at a uniform rate 104 Bending of reinforcement with temperature below 0degC shall only be performed on steel of given qualityspecified in Section 4105 FRP bars can be cut to specified length but shall otherwise be used in the as delivered shapes FRP barscannot be bent to shape106 Welding of steel reinforcement shall be carried out by qualified welders working in accordance withapproved procedures The welds shall be non-destructively examined to the extent given in the approvedspecification Production tests of such welds shall be considered for special welds of importance TheProduction tests and quality of the welding procedures shall be documented107 Steel welding is only permitted on reinforcing steel that is classified as weldable in the relevant productstandard according to ISO 6935 or international standards

108 Steel welding shall be used and performed in accordance with specifications by design and shallconform to special requirements in international standards as relevant109 Steel welding should not be executed at or near bends in a bar unless specifically approved by the design110 Steel welding of galvanized or epoxy-coated reinforcement is only permitted when a procedure for repairis specified and approved111 For steel bars wires welded reinforcement and fabric bent after welding the diameter of the mandrelused should be as specified by design and in accordance with the standard relating to the type of reinforcementUnder no condition shall reinforcement be bent over a mandrel with diameter which is not at least 15 timesgreater than a test mandrel used to document by bending tests what that steel and bar diameter can take withoutcracking or damage112 In-place bending of steel in the formwork may be allowed if it can be demonstrated that the prescribedbending radius is obtained and the work can be performed without misplacing the reinforcement113 The straightening of steel bent bars is prohibited unless the bars are originally bent over a mandrel witha diameter at least 15 times greater than a test mandrel used to document what that particular steel and bardiameter can take and be straightened without damage a procedure for such work shall be prepared andapproved114 Steel reinforcement delivered on coil shall be handled using the appropriate equipment straighteningshall be performed according to approved procedures and all required mechanical properties maintained115 Prefabricated reinforcement assemblies cages and elements shall be adequately stiff and strong to bekept in shape during transport storage placing and concreting They shall be placed accurate so that they meetall the requirements regarding placing tolerances for reinforcement116 Steel deformed high bond bars may be bundled in contact to ensure adequate concrete penetration intoareas with congested reinforcement Special attention shall be given to the possibility of water channels alongthe bars in such cases For structures required to be watertight no more than 4 bars including the splices (seeSec6 Q303) are allowed to be in the same bundle at any section117 The reinforcement shall be supported and fixed in a manner which prevents accidental movement duringcompletion of the formwork and the casting compaction and vibration of the concrete118 The specified concrete cover shall be ensured by securely fixed sturdy spacers Wooden spacers areprohibited119 Attention shall be paid to the execution and detailing of reinforcement at construction joints and the areasaround prestressing anchorages120 Joints on bars shall be done by laps or couplers Only couplers whose effectiveness is tested andapproved may be used Butt-welds may be permitted for steel reinforcement to a limited extent but only whensubject to prequalification testing with non-destructive examination and visual quality inspection of all weldsduring execution The welds shall be identified on design drawings121 The length and position of lapped joints and the position of couplers shall be in accordance with designdrawings and the project specification Staggering of such joints shall be considered in design For details seeSection 6122 The reinforcement shall be placed according to the design drawings and fixed within the tolerances forfixing of reinforcement in this Standard and secured so that its final position is within the tolerances given inthis Standard For details see Section 6123 Assembly of steel reinforcement should be done by tie wire Spot or tack welding is not allowed for theassembling of reinforcement unless permitted by national standards and the project specification and dueaccount has been taken of the risk of fatigue failure of the main rebar at the weld124 The specified cover to the reinforcement shall be maintained by the use of suitable chairs and spacersSpacers in contact with the concrete surface in corrosive atmosphere shall be made from concrete of at leastthe same quality as the structure Detailed requirements to concrete cover are given in Sec6 Q100 and Sec6Q200125 In areas of congested reinforcement measures shall be taken to ascertain that the concrete can flow andfill all voids without segregation and can be adequately compacted126 FRP reinforcement shall be handled with care FRP bars which are damaged in storage and handling priorto during installation and prior to casting shall be replaced127 FRP reinforcement has a density of same magnitude as that of concrete The consequence is that thereinforcement may float up during vibration The fixing of the FRP reinforcement shall be done consideringthis consequence

H 200 Prestressing ducts and anchorages201 The prestressing assembly eg all components of the tendons shall be assembled in accordance withsuppliers specifications or approval documents and as shown in the approved for construction drawings

202 The surfaces of ducts and anchorages shall be free of substances that may be harmful to the material orto the bond and shall be protected from such substances until casting of concrete commences All componentsof the entire prestressing assembly or system consisting eg of prestressing reinforcement ducts sheathsanchorage devices couplers as well as prefabricated tendons and tendons fabricated on site shall be protectedfrom harmful influences during transport and storage and also whilst placed in the structure prior to permanentprotection The ducts and anchorages shall be examined for mechanical damage and corrosion beforeinstallation

203 Approval documents identification documents and certification of tests on materials andor tendonsshall be available on site Each item or component shall be clearly identified and traceable

204 Documentation of prestressing steel of different deliveries shall be made in the as-built records

205 Cutting shall be done by an appropriate method in a way that is not harmful

206 Prestressing steel shall not be subject to welding Steel in the vicinity of prestressing steel shall not besubject to oxygen cutting or welding except when sufficient precaution have been taken to avoid damage toprestressing steel and ducts

207 The prestressing assembly shall be placed in compliance with the projectsuppliers specification and inaccordance with the relevant construction drawings The tendon and all components shall be placed andsecured in a manner that maintains their location within the permissible tolerances for position angulardeviation straightness andor curvature Tendons shall not sag or have kinks of any kind The ducts andanchorages shall be installed and fixed to prevent accidental movement during completion of the formwork andthe casting compaction and vibration of concrete

208 The straight entry into anchorages and couplers as well as the co-axiality of tendon and anchorage shallbe as specified by the suppliers specifications or system approval documents

209 Care shall be taken during the installation and fixation of ducts to avoid undulations that may cause airand water pockets away from the high point vents during grouting

210 Vents and drains on the sheaths shall be provided at both ends and at all points where air or water canaccumulate In the case of sheaths of considerable length inlets vents and drains might be necessary atintermediate positions As alternative to drains other documented methods of removing water may beconsidered

211 Inlets vents and drains shall be properly marked to identify the cable

212 The sheaths and their joints shall be sealed against ingress of water and the ends shall be capped to avoidrain dirt and debris of any kind They shall be secured to withstand the effects of placing and compacting ofthe concrete

213 Sheaths shall be checked after pouring of concrete to ensure sufficient passage for the tendons

214 Sheaths shall be cleared of any water immediately prior to tendon threading

H 300 Embedded steel

301 Embedded steel in the form of penetrations surface embedments etc shall be of type and dimensionsand shall be placed as shown on approved drawings

302 The surfaces of embedments shall be free of substances that may be harmful to the material or the bondand shall be protected from such substances until casting of concrete commences The embedments shall beexamined for mechanical damage and corrosion before installation

303 Embedments shall be securely fixed at their location to prevent any accidental movement duringsucceeding construction stages

304 Due consideration shall be given where relevant to heat transfer into the concrete during welding andthe corresponding effects on concrete quality anchoring bond as well as the quality of the welding

305 Adequate sealing shall be provided around embedments to prevent ingress of seawater to thereinforcement Materials (waterstops or similar) and procedures for the sealing shall be in accordance with theapproved specification Temporary embedments shall be protected against corrosion unless it can bedemonstrated that their corrosion will not cause concrete spalling endangering the reinforcement

H 400 Inspection and survey

401 During and after installation of reinforcement ducts anchorages and embedments survey and inspectionshall be performed The survey and inspection is as a minimum to include

mdash dimensions type grade spacing and concrete cover for reinforcementmdash type dimensions and location of ducts and anchoragesmdash type and location of embedmentsmdash compliance with installationoperation procedures

I Production of Concrete and Grout

I 100 General101 All the required properties for the concrete to achieve its service functions shall be identified Theproperties of the fresh and hardened concrete shall take account of the method of execution of the concreteworks eg placing compaction formwork striking and curing 102 Prior to any concreting the concrete shall be documented by pretesting to meet all the requirementsspecified Testing may be performed based on laboratory trial mixes but should preferably also include a full-scale test from the batch plant to be used Documented experience from earlier use of similar concrete producedon a similar plant with the same constituent materials may be regarded as valid pretesting The quality controlprocedures shall be available at site The procedures shall include the possible corrective actions to be taken inthe event of nonconformity with the project specification or agreed procedures For details see Section 4103 The various mix designs shall be approved for their intended applications and the mix proportionsrecorded again see Section 4 Each approved mix design shall be allocated an identification symbol and themix designs shall be related to the part of the structure or construction phase where they are intended to be used104 The lay-out and mixing procedures to be used at the mixing plant shall be described and approved priorto start of construction The description shall contain

mdash description of plant lay-out and equipmentmdash qualification of personnelmdash mixing time for wet and dry mixingmdash methods of weighing and required tolerancesmdash method for monitoring fresh mix consistency

105 The constituent materials shall be weighed volumetric batching shall not be used unless adequateaccuracy is documented regularly The quantity of water used in the mixes shall be adjusted according to thewater content of the aggregates106 In special cases it may be required to maintain the temperature of the fresh mix at certain levels Coolingof constituent materials or addition of ice may be sufficient to bring about the desired cooling of the fresh mixConversely heating of constituent materials such as steaming of frozen aggregates may be applicable Theusefulness of the methods and their influence on the properties of the mix design shall be investigateddocumented and approved before such methods are used107 Survey and inspection shall be performed during production of concrete and grout and should as aminimum include

mdash Compliance with mix design and mixing proceduresmdash Compliance with sampling and test intervalsmdash Compliance with specified Method Statementsmdash Review of the Contractors internal QC controls for casting operations

J Transport Casting Compaction and Curing of Concrete

J 100 Transport101 Transport of concrete from the mixing plant to the place of casting shall be performed in a manner thatprovides optimum quality concrete at the place of casting Segregation in the fresh concrete shall be avoidedand in cases where early setting may represent a problem the maximum time allowed between emergence fromthe mixer and completed casting shall be specified and approved102 Rotating truck mixers shall be used for road transport from the mixing plant Transport in a non-rotatingvessel should be avoided except for very short distances Pumping or skips should be used for placing theconcrete in the forms Other methods for placement may also be considered103 Concrete shall be inspected at the point of placing and in the case of ready-mixed concrete also at thepoint of delivery Samples for acceptance testing shall be taken at the point of placing in the case of ready-mixed concrete samples for identity testing shall be taken at the point of delivery104 Detrimental changes of the fresh concrete such as segregation bleeding paste loss or any other changesshall be minimized during loading transport and unloading as well as during conveyance or pumping on site105 Concrete may be cooled or heated either during mixing during transport to site or at site if documentedacceptable by pretesting The temperature of the fresh concrete shall be within the specified or declared limits106 The maximum amount of water that may be added to the concrete during the transport shall be specifiedand be in accordance with the pretesting documentation107 When pumping is used for the casting of large sections a sufficient number of back-up units shall beprovided

J 200 Casting and compaction

201 A procedure for the casting process shall be prepared and submitted for approval by clientverificationauthority The procedure is as a minimum to specify

mdash inspection requirements prior to castingmdash maximum thickness of each new layer of concretemdash maximum thickness of concrete that may remain not setmdash maximum temperature to be allowed in the concrete during curingmdash maximumminimum temperature of the fresh mix at the place of castingmdash extent of vibration and re-vibrationmdash contingency measures in case of form stop blockage equipment failure etc

202 Before casting commences examination of the formwork reinforcement ducts anchorages andembedments shall be completed with acceptable results Immediately before placing of the concrete theformwork shall be examined for debris and foreign matters detrimental to concrete quality The form shall befree of detritus ice snow and standing water

203 Construction joints shall be prepared and roughened in accordance with project specifications Inmonolithic structures an adequately roughened surface may be obtained by the application of a surface retarderon the fresh concrete and later cleaning by water jetting Construction joints shall be clean free of laitance andthoroughly saturated with water but surface dry Construction joints in contact with the section to be cast shallhave a temperature that does not result in the adjoining concrete freezing Particular care shall be exercised inthe preparation of construction joints in sections of the structure that shall remain watertight in temporary oroperational phases

204 During casting care shall be exercised when placing the concrete in the forms so that accidentaldisplacement of reinforcement embedments etc will not occur

205 The concrete shall be placed and compacted in order to ensure that all reinforcement and cast-in itemsare properly embedded in compacted concrete and that the concrete achieves its intended strength anddurability Vibration and compaction shall ensure thorough compaction penetration of concrete into voids andhomogeneous concrete Direct contact between vibrators and reinforcement shall be avoided

206 Appropriate procedures shall be used where cross-sections are changed in narrow locations at box outsat dense reinforcement arrangements and at construction joints Settlement cracking over reinforcement in topsurface shall be avoided by re-vibration

207 Casting of sections exceeding one metre in thickness and very large pours require preparation of specialprocedures Necessary precautions to be specified in the procedures may include

mdash artificial cooling of the fresh mixmdash cooling of the concrete during curingmdash insulation of the concrete to ensure an even temperature distribution during the first weeks of coolingmdash special formwork for the casting operation

208 The rate of placing and compaction shall be high enough to avoid cold joints and low enough to preventexcessive settlements or overloading of the formwork and falsework The concrete shall be placed in layers ofa thickness that is compatible with the capacity of the vibrators used The concrete of the new layer should bevibrated systematically and include re-vibration of the top of the previous layer in order to avoid weak orinhomogeneous zones in the concrete The vibration shall be applied until the expulsion of entrapped air haspractically ceased but not so as to cause segregation or a weak surface layer

209 Concrete shall be placed in such a manner as to avoid segregation Free fall of concrete from a height ofmore than 2 m shall not be permitted to occur unless the mix is demonstrated to allow this without segregation

210 Concrete should be compacted by means of high frequency vibrators Contact between internal vibratorsand reinforcement or formwork shall be avoided as much as possible Vibrators shall not be used for horizontaltransportation (spreading) of concrete

211 Alternative methods to the use of internal vibrators in order to obtain an adequately compacted concretemay be permitted provided this can be documented for the relevant type of conditions by trial casting

212 Concrete which does not require the use of vibrators in order to obtain an adequately compacted statedue to the makeup of its mix design shall have its adequacy documented prior to its specification

213 Low temperature concreting may require special procedures to ensure that the concrete reaches adequatematurity Necessary precautions to be specified in the procedures may include

mdash heating the concrete mixmdash use of accelerators in the concrete mixmdash heated andor insulated formwork

214 Hot weather concreting shall be performed carefully and the references to the maximum temperature of

the concrete during curing shall be followed to avoid excessive dehydration of the concrete If the ambienttemperature is forecast to be above 30degC at the time of casting or in the curing period precautions shall beplanned to protect the concrete against damaging effects of high temperatures215 During placing and compaction the concrete shall be protected against adverse solar radiation and windfreezing water rain and snow Surface water shall be removed during concreting if the planned protection fails216 For underwater concreting special procedures shall be prepared and their adequacy documented217 Records shall be kept during the casting operations Each batch shall be recorded with regard to allspecified and relevant information eg mix identification contents of constituent materials weights mixingtime date and time of mixing temperatures of the mix part of the structure reference to test samples taken etc218 During casting of concrete survey and inspection shall be performed to ensure compliance with theapproved procedure219 Special concreting methods shall be stated in the project specification or agreed220 Special execution methods shall not be permitted if they may have an adverse effect on the structure orits durability Special execution methods might be required in cases where concrete with lightweight orheavyweight aggregates are used and in the case of under-water concreting In such cases procedures for theexecution shall be prepared and approved prior to the start of the work Trials might be required as part of thedocumentation and approval of the methods to be used221 Concrete for slip-forming shall have an appropriate setting time Slip-forming shall be performed withadequate equipment and methods for transportation to the form and distribution at the form The methodsemployed shall ensure that the specified cover to the reinforcement the concrete quality and the surface finishare achieved

J 300 Curing301 Concreting procedures shall ensure adequate curing in order to obtain maximum durability minimizeplastic shrinkage losses in strength and durability and to avoid cracking The curing period is normally not tobe less than two weeks The duration of curing may be further estimated based on testing of strength oralternatively by the maturity of the concrete on the basis of either the surface temperature of the concrete or theambient temperature The maturity calculation should be based on an appropriate maturity function proven forthe type of cement or combination of cement and addition used302 During curing the concrete surface is as far as practicable to be kept wet with fresh water Care shall betaken to avoid rapid lowering of concrete temperature (thermal shock) caused by applying cold water on hotconcrete surfaces Seawater shall not be used for curing Fresh concrete shall not be permitted submerged inseawater until an adequate strength of the surface concrete is obtained If there is any doubt about the abilitycapacity to keep the concrete surfaces permanently wet for the whole of the curing period or where there isdanger of thermal shock a heavy duty curing membrane shall be used303 Whenever there is a possibility that the concrete temperature may fall below the freezing point duringcuring adequate insulation shall be provided304 On completion of compaction and finishing operations on the concrete the surface shall be cured withoutdelay If needed to prevent plastic shrinkage cracking on free surfaces temporary curing shall be applied priorto finishing305 Curing compounds are not permitted on construction joints on surfaces where bonding of other materialsis required unless they are fully removed prior to the subsequent operation or they are proven to have nodetrimental effects to bond306 Early age thermal cracking resulting from thermal gradients or restraints from adjoining members andpreviously cast concrete shall be minimized In general a differential in temperature across a section shouldnot be allowed to exceed 10degC per 100 mm307 The concrete temperature shall not fall below 0degC until the concrete has reached a compressive strengthof at least 5 MPa and also is adequate for all actions in frozen and thawed condition until the specified fullstrength is gained Curing by methods using water shall not be done if freezing conditions are likely In freezingconditions concrete slabs and other elements that may become saturated shall be protected from the ingress ofexternal water for at least seven days308 The peak temperature of the concrete within an element shall not exceed 70degC unless data aredocumenting that higher temperatures will have no significant adverse effect309 The set concrete shall be protected from vibrations and impacts that can damage the concrete or its bondto reinforcement310 The surface shall be protected from damage by heavy rain flowing water or other mechanical influences

J 400 Completion401 Formwork shall not be removed until the concrete has gained the strength required to support itself andwithstand other relevant loads imposed by the environment or construction activities

402 After removal of the formwork tie-rods spacer bars etc shall be broken off at a level corresponding tothe concrete cover and the holes patched with cement mortar

403 The concrete surface shall be examined and areas subject to repair marked out If any areas show visiblesigns of inferior quality the area shall be marked for possible testing of concrete quality

K Completion of Prestressing Systems

K 100 Threading and stressing of tendons

101 Before threading of tendons is commenced the anchorages and ducts shall be examined for possibledamages attacks of corrosion blockage of ducts by concrete the integrity of the ducts and water tightness Allducts shall be cleared by compressed air or similar means prior to threading of tendons

102 Tendons shall be examined for damages corrosion dimension and identification before they arethreaded

103 Stressing of tendons shall be carried out according to the system manufacturers or other approvedprocedure which as a minimum shall specify

mdash the sequence of stressing for multiple cablesmdash the number of stressing stepsmdash elongation versus loadmdash amount of overstressing to compensate for creepmdash requirements to equipment

104 Stressing of tendons shall be carried out by personnel with documented qualification eg previousexperience or adequate training

105 On completion of stressing operations protruding ends of tendons shall be protected

106 The final stress in each tendon shall be recorded

107 During threading and stressing of tendons survey and inspection shall be performed to ensurecompliance with the approved procedure

K 200 Tensioning of tendons

201 Tensioning shall be done in accordance with an approved method statement giving the tensioningprogramme and sequence The jacking forcepressure and elongation at each stagestep in the stressingoperation until full force is obtained shall be recorded in a log The obtained pressures and elongations at eachstagestep shall be compared to pre-calculated theoretical values The results of the tensioning program and itsconformity or non-conformity to the requirements shall be recorded All observations of problems during theexecution of the prestressing works shall also be recorded

202 Stressing devices shall be as permitted for the prestressing system The valid calibration records for theforce measuring devices shall be available on the site before the tensioning starts

203 Application andor transfer of prestressing forces to a structure may only be at a concrete strength thatmeets the requirements as specified by design and under no condition shall it be less than the minimumcompressive strength stated in the approval documents of the prestressing system Special attention in thisrespect shall be paid to the anchorage areas

K 300 Pre-tensioning

301 Pre-tensioning is normally carried out under manufacturer condition and the tendons are stressed priorto casting the concrete If during stressing the calculated elongation cannot be achieved within a range of

plusmn3 for a group of tendons orplusmn5 for a single tendon within the group for the specified tensioning force

action shall be taken in accordance with the method statement either to the tensioning program or to the design

302 The release of prestressing force in the rigbed shall be done in a careful manner in order not to affect thebond in the anchorage zone of the tendon in a negative manner

303 If the fresh concrete cannot be cast in due time after tensioning temporary protective measures shall betaken which will not affect the bond or have detrimental effect on the reinforcement andor the concrete

304 Pre-tensioning will normally not be used as prestressing method for large offshore structures Howeverif the offshore structure is assembled by precast elements pre-tensioning may be applied

305 Only qualified methods of prestressing of FRP shall be used

K 400 Post-tensioning

401 Tensioning shall not take place at temperatures below +5degC within the structure unless specialarrangements can assure the corrosion protection of non-grouted tendons Tensioning is prohibited attemperatures below -10degC

402 If during the stressing operation the calculated elongation cannot be achieved within a range of

Action shall be taken in accordance with the method statement either to the tensioning programme or to thedesign

403 In the case of deviations from the planned performance during tensioning tendon-ends shall not be cutoff and grouting is not permitted Works that can impair re-tensioning shall not be carried out No tendons shallbe cut if the obtained elongations deviate from the theoretical by more than 5 without design approvalFurther work shall be postponed until the tendon has been approved or further action decided

NoteIn case of deviations between theoretical and obtained results tests to confirm friction factors and E-modulus of thetendon assembly might be necessary

---e-n-d---of---N-o-t-e---

404 The prestressing tendons shall be protected from corrosion in the period from threading to prestressingThis period should normally not be allowed to exceed one week Should the period from threading to castingexceed one week then the condition of the tendons shall be specially evaluated for harmful conditions andspecial precautions may be required to protect the tendons

K 500 Protective measures grouting greasing concreting

501 Tendons placed in sheaths or rigid ducts in the concrete couplers and anchorage devices shall beprotected against detrimental corrosion This protection shall be ensured by filling all voids with a suitablegroutinginjection material such as grout grease or wax Anchorage areas and end caps shall be protected aswell as the tendons

502 In case of post-tensioning with required bond cement grouting of sheaths shall comply with recognizedinternational or national standards Groutinginjection shall follow as soon as possible after tensioning of thetendons normally within one week If a delay is likely to permit corrosion protective measures should beconsidered in accordance with national regulations or recommendations by the supplier

503 A method statement shall be provided for the preparation and execution of the groutinginjection allimportant dataobservations from the grouting shall be reported in a log eg volume consumed compared totheoretical volume temperature of the structure and mix proportions and problemsstops

504 Grouting devices shall be as permitted for the prestressing system

K 600 Unbonded tendons

601 Anchorage areas of un-bonded tendons or single strands their sheaths and end-caps shall be filled bynon-corrosive grease or wax End caps shall be encased in concrete tied to the main structure by reinforcement

602 Sheathed un-bonded tendons shall be adequately sealed against penetration of moisture at their ends

K 700 Grouting of ducts

701 For general requirements to grouting operations see Q

702 In vertical ducts the grouting pressure shall be given particular attention Normally the grout pressureinside the duct should not be allowed to exceed 2 MPa unless permitted by the design

703 In vertical or inclined ducts or ducts of particularly large diameter post-injection might be necessary inorder to remove bleed water or voids Post-injection shall be performed before the grout is stiffened If voidsare detected at inlets or outlets after the grout is stiffened post-grouting shall be carried out if required byvacuum grouting

704 Provision for vacuum grouting or reinjection shall be made in case of discovery of a blockage in a posttensioning duct Ducts shall under no circumstances be left empty and un-grouted without specific approval bydesign

705 In case of vacuum-injection the free volume in the ducts shall be measured The amount of grout injectedshall be comparable with this volume Vacuum grouting procedures particularly in the case of vertical tendonsshould be prequalified by trials of relevant geometry

706 After completion of grouting unintended loss of grout from the ducts shall be prevented by sealing themunder pressure of minimum 05 MPa for a minimum of one minute

707 If grouting of a duct is interrupted corrective actions such as washing out all fresh grout shall be takenNo ducts shall be left with incomplete filling of grout

K 800 Greasing operations801 Greasing shall be carried out at continuous and steady rate After completion of greasing unintended lossof grease from the ducts shall be prevented by sealing them under pressure802 The volume of the injected grease shall be checked against the theoretical free volume in the duct Thechange of volume of the grease with change in temperature shall be taken into account

L Repairs

L 100 General101 Procedures for the execution of repairs shall be prepared General procedures appropriate for the mostcommon types of repairs are normally to be available at the start of construction Further procedures shall beprepared if repairs not covered by the initial procedures shall be performed The procedures are as a minimumto contain the following information

mdash criteria and authority for deciding implementation of repairsmdash necessary equipmentmdash qualification of personnelmdash required ambient conditions (eg temperature)mdash repair material specificationmdash repair execution descriptionmdash procedure testingmdash inspection and testing

102 Materials for repair during construction shall be approved for use in advance Documentation of relevantproperties shall be submitted and include

mdash strength and strength developmentmdash deformation characteristicsmdash thermal propertiesmdash bond to concretemdash chemical compatibility with concretemdash stabilitydurability in future environmentmdash pot life

103 Execution of repairs shall be performed by experienced personnel with documented capabilities Prior tothe actual execution procedure testing may be required to document

mdash feasibility of repairmdash in-place strengthmdash special requirements

104 Execution and testing of repairs shall be surveyed and inspected for compliance with approved procedures

M Corrosion Protection

M 100 General101 Survey and inspection and execution of corrosion protection systems shall be in accordance with therequirements in Section 5 and Section 6 as relevant

N Site Records and As-built Documentation

N 100 General101 Adequate records related to the construction of the structure shall be prepared Construction records shallbe compiled in parallel with the construction process Compiled records shall be systematic and fully traceableSuch records shall include details of all testing alterations additions corrections and revisions made duringthe construction period in order to provide information required during the in-service life of the structure102 As a minimum the construction records shall contain

mdash quality assurancequality control manual

mdash relevant material certification and test reportsmdash summary testing reports of constituent materials additives and reinforcementmdash summary reports of production testing of concrete and grout with reference to location in the structuremdash summary report of testing of concrete in the structuremdash summary reports from stressing of prestressing system including final stressesmdash summary of repair work including location referencesmdash documentation of welding and structural steel workmdash dimensional control reports of final geometry of cross sections overall geometry (including deviation from

theoretical shape and out of alignment) placing of prestressing ducts and anchorages and location ofembedments

mdash inspection summary reportsmdash as-built drawingsmdash information with regard to any non-conformances mdash information with regard to any waivers or modifications from the specified requirementsmdash information with regard to storage handling installation testing and operation of items shipped with the structure

O Precast Concrete Elements

O 100 General101 This clause specifies requirements for the construction operations involving precast elements whetherproduced in a factory or a temporary facility at or outside the site and applies to all operations from the timethe elements are available on the site until the completion of the work and final acceptance102 When precast elements are used in Offshore Concrete Structures their manufacture and design arecovered by this Standard Therefore they shall meet all requirements to materials strength and durability as ifthey were cast in-situ103 When precast elements are used these shall be designed for all temporary conditions as well as thestructural performance in the overall structure This shall at least cover

mdash joints with any bearing devices other connections additional reinforcement and local groutingmdash completion work (in-situ casting toppings and reinforcement)mdash load and arrangement conditions due to transient situations during execution of the in-situ worksmdash differential time dependent behaviour for precast and in-situ concrete

104 Precast elements shall be clearly marked and identified with their intended position and in case of anyambiguity due to visual symmetry also marked and identified with their lateral and vertical orientation in thefinal structure As built information and records of conformity testing and control shall be available105 A complete erection work program with the sequence of all on-site operations shall be prepared basedon the lifting and installation instructions and the assembly drawings Erection shall not be started until theerection program is approved

O 200 Handling and storage201 Instructions shall be available giving the procedures for the handling storage and protection of theprecast elements202 A lifting scheme defining the suspension points and forces the arrangement of the lifting system and anyspecial auxiliary provision shall be available The total mass and centre of gravity for the elements shall begiven203 Storage instructions for the element shall define the storage position and the permissible support pointsthe maximum height of the stack the protective measures and where necessary any provisions required tomaintain stability

O 300 Placing and adjustment301 Requirements for the placing and adjustment of the precast elements shall be given in the erectionprogram which shall also define the arrangement of the supports and possible temporary stability provisionsAccess and work positions for lifting and guiding of the elements shall be defined The erection of the elementsshall be performed in accordance with the assembly drawings and the erection program302 Construction measures shall be applied which ensure the effectiveness and stability of temporary andfinal supports These measures shall minimize the risk of possible damage and of inadequate performance303 During installation the correct position of the elements the dimensional accuracy of the supports theconditions of the element and the joints and the overall arrangement of the structure shall be checked and anynecessary adjustments shall be made

O 400 Jointing and completion works401 The completion works are executed on the basis of the requirements given in the erection program andtaking climatic conditions into account

402 The execution of the structural joints shall be made in accordance with the project specifications Jointsthat shall be concreted shall have a minimum size to ensure a proper filling The faces shall normally meet therequirements to construction joints

403 Connectors of any type shall be undamaged correctly placed and properly executed to ensure aneffective structural behaviour

404 Steel inserts of any type used for joint connections shall be properly protected against corrosion and fireby an appropriate choice of materials or covering

405 Welded structural connections shall be made with weldable materials and shall be inspected

Threaded and glued connections shall be executed according to the specific technology of the materials used

P Geometrical Tolerances

P 100 General

101 Design tolerances are specified in Sec6 C100 The design assumption is based on an alternativeapproach either

mdash Design and construct in accordance with the tolerances in Sec6 C100 with high material factors ormdash Design and construct for any tolerances the maximum positive and negative tolerances have to be included

in design in the most design critical way and the construction work has to confirm compliance with the setof tolerances

102 This clause defines the types of geometrical deviations relevant to offshore structures see P300 P400and P500 The list is provided as guidelines and the designer shall fill in the required tolerances to be used inconstruction The tolerances shall be marked on the drawings issued for construction

103 In general tolerances on dimensions are specified in order to ensure that

mdash Geometry is such as to allow parts fit together as intendedmdash Geometrical parameters used in design are satisfactorily accuratemdash The structural safety of the structural member is ensuredmdash Construction work is performed with a satisfactorily accurate workmanshipmdash Weights are sufficiently accurate for floating stability considerations

104 All these factors shall be considered when tolerances are specified Tolerances assumed in design (SeeSec6 C100) may be greater than the tolerances actually found to be acceptable for other reasons

105 Changes in dimensions following temperature effects concrete shrinkage post-tensioning andapplication of loading including those resulting from different construction sequences are not part of theconstruction tolerances When deemed important these changes shall be considered separately

P 200 Reference system

201 A system for setting out tolerances and the position points which mark the intended position for thelocation of individual components shall be in accordance with ISO 4463-1

202 Deviations of supports and components shall be measured relative to their position points If a positionpoint is not established deviation shall be measured relative to the secondary system A tolerance of positionin plane refers to the secondary lines in plane A tolerance of position in height refers to the secondary lines inheight

P 300 Member tolerances (Guidelines)

301 Requirements may be given for the following type of tolerances as relevant

a) skirts

mdash deviation from intended centre for circular skirtsmdash deviation from intended position for individual points along a skirtmdash deviation from best fit circle for circular skirtsmdash deviation from intended elevation for tip and top of skirtmdash deviation from intended plumb over given heights

b) slabs and beams

mdash deviation from intended elevation for centre planemdash deviation from intended planeness measured over given lengths (2 m and 5 m)mdash deviation from intended slope

c) walls columns and shafts

mdash deviation from intended position of centre plane or horizontal centre line mdash deviation from intended planeness - horizontal directionmdash deviation from intended planeness - vertical directionmdash deviation from intended plumb over given heights

d) domes

mdash deviation of best fit dome centre from intended centre horizontal and vertical directionsmdash deviation of best fit inner radius from intended radiusmdash deviation of individual points from best fit inner domemdash deviation of individual points from best fit exterior dome

e) circular members

mdash deviation of best fit cylinder centre from intended centre linemdash deviation of best fit inner radius from intended inner radiusmdash deviation of individual points from best fit inner circle over given lengthsmdash deviation of individual points from best fit exterior circle over given lengths mdash deviation from intended plumb over given height

f) shaftdeck connections

mdash deviation of best fit centre from intended centre of shaftmdash deviation in distances between best fit centres of shaftsmdash position of temporary supports horizontal and verticalmdash position of anchor bolts horizontal plane and verticality

P 400 Cross-sectional tolerances (Guidelines)401 Requirements may be given for the following type of tolerances

a) thickness

mdash individual measured points mdash overall average for area

b) reinforcement position

mdash tolerance on concrete cover mdash tolerance on distance between rebar layers same face mdash tolerance on distance between rebar layers opposite facesmdash tolerances on spacing of rebars in same layer mdash tolerances on lap lengths

c) prestressing

mdash tolerance on position of prestressing anchorsmdash position of ductsstraightness at anchorsmdash position of ducts in intermediate positionsmdash tolerances on radius for curved parts of tendons

P 500 Embedments and penetrations (Guidelines)501 Requirements may be given for the following type specified of tolerances as relevant Tolerances shallbe for items individually or for groups as appropriate

a) embedment plates

mdash deviation in plane parallel to concrete surfacemdash deviation in plane normal to concrete surfacemdash rotation in plane of plate (degrees)

b) attachments to embedments

mdash deviation from intended position (global or local system)

c) penetrations

mdash sleeves deviation from intended position of centremdash sleeves deviation from intended directionmdash manholes deviation from intended position and dimension

mdash blackouts deviations from intended position and dimensions

Q Grouting Operations

Q 100 General101 The grouting operation shall be conducted with strict adherence to the approved procedure Theapplicability of the procedure for the intended operation and likely environmental conditions shall bedocumented through testing onshore102 Prior to start of operation it shall be ensured that the grouting system is operable and that air and surplusgrout may be evacuated from the volume at a rate exceeding the filling rate Means shall be provided to observethe emergence of grout from the various emergence points 103 Grouting with cement-based grouts should only be conducted if the ambient temperatures range between+5degC to +30degC If a low or elevated temperature testing programme documenting the properties of the materialhas been conducted grouting outside this range may be permitted104 The recorded grout temperature during production should not be less than + 10degC nor above +25degCduring placement without due consideration of pumpability Pumpability of the grout at elevated temperaturesshould be verified by means of full scale testing105 If the temperature in the structure is above +30degC grouting may be permitted provided specialprecautions including documented material properties for application above this temperature can ensure asuccessful grouting operation106 A grouting procedure shall be prepared and submitted for approval The procedure shall as a minimumcontain the following information

mdash requirements to fresh grout properties bleeding viscosity density etcmdash requirements to hardened groutmdash batching and mixing requirementsmdash means of transportation of fresh groutmdash requirements to pumps and other equipmentmdash grouting pressuremdash holding timemdash number and placing of ventsmdash particulars of difficult operations such as grouting of long vertical ductsmdash grout quality sampling points and proceduremdash contingency measures in case of equipment failure blockages etc

107 Grouting shall be carried out at a continuous and steady rate from the lowest inlet until the emerginggrout has the appropriate quality not affect by evacuated water or in the case of ducts preservation oil 108 Non-retarded grout and grout with an expanding admixture shall be used within 30 min after mixingunless otherwise proven by testing109 Records shall be kept during the grouting operation Each batch shall be recorded with regard to thespecified and relevant information eg mix identification constituent materials weights mixing time date andtime of mixing volume duct being grouted reference to test samples taken etc110 During the grouting operation survey and inspection shall be performed to ensure compliance with theapproved procedure111 For grouting of post tensioning ducts see K700

SECTION 8IN-SERVICE INSPECTION MAINTENANCE AND CONDITIONAL

MONITORING

A General

A 100 Application101 The purpose of this section is to specify requirements and recommendations for in-service inspectionmaintenance and condition monitoring of Offshore Concrete Structures and to indicate how these requirementsand recommendations can be achieved Alternative methods may also fulfil the intent of these provisions andcan be applied provided they can be demonstrated and documented to provide the same level of safety andconfidence102 Requirements for in-service inspection maintenance and condition monitoring for concrete offshorestructures in general are given under this Sub-section

A 200 Scope201 The In-service inspection maintenance and condition monitoring programme shall be established as partof the design process considering safety environmental consequences and total life cycle costsThe overall objective for the inspection maintenance and condition monitoring activities shall ensure that thestructure is suitable for its intended purpose throughout its lifetimeThe condition monitoring activities should include the latest developments knowledge and experienceavailable Special attention should be paid to deterioration mechanisms for the relevant materials and structuralcomponents

mdash time-dependent effectsmdash mechanicalchemical attacksmdash corrosion loadingmdash seabed conditionsmdash stabilitymdash scour protection and damage from accidents

As appropriate the condition monitoring activities should reflect the need for repair works and maintenanceMaintenance shall be carried out according to a plan based on the expected life of the structure or componentor when the specified inspection or monitoring efforts detect unpredicted happenings

A 300 Personnel qualifications301 Personnel involved in inspection planning and condition assessment shall have relevant competence withrespect to marine concrete design concrete materials technology concrete construction and specific experiencein the application of inspection techniques and the use of inspection instrumentation and equipment Becauseeach offshore structure is unique inspectors shall familiarize themselves with the primary design andoperational aspects before conducting an inspection302 Inspectors shall have adequate training appropriate for supervisors divers ROV-operators as specifiedin accordance with national requirements where applicable

A 400 Planning401 The planning of in-service inspection maintenance and condition monitoring activities shall be based onthe

mdash function of each structural elementmdash exposure to damagemdash vulnerability to damagemdash accessability for inspection

402 The condition of the loadbearing structure shall be documented by periodic examinations and whererequired supplemented by instrumentation-based systems A programme for planning and implementation ofinspection and condition monitoring including requirements for periodic inspections shall be prepared Theprogramme for inspection and condition monitoring shall cover the whole structure and comprise the use ofinstrumentation data403 If values for loads load effects erosion or foundation behaviour are highly uncertain the installationshall be equipped with instrumentation for measurement of environmental condition dynamic motion strainetc to confirm the applicability of governing design assumptions Significant changes to equipment andstorageballast operations should be identified and recorded

404 Continuous monitoring shall be carried out to detect and give warnings regarding damage and seriousdefects which significantly reduce the stability and load carrying capacity Significant events are those thatwithin a relatively short period of time can cause structural failure or those that represent significant risk topeople or the environment or those having large economic consequences Forecasting the occurrence of theseevents is needed to allow sufficient lead-time for corrective action (eg to repair) or abandonment405 The structure should also be monitored to detect small damages and defects which can develop to acritical situation Particular emphasis should be placed on identifying the likelihood of small failures whichcan lead to progressive collapse The type and extent of monitoring on this level should be handled as a riskminimization problem which includes the probability of damagedefect occurrence detection probabilitymonitoring costs and cost savings by repairing the damagedefect at an early stage

A 500 Programme for inspection and condition monitoring

501 The first programme for inspection and condition monitoring should provide an initial assessment asdescribed in A602 of the condition of the structure ie the assessment should have an extent and durationwhich as far as possible provides a total description of the condition of the structure (design verification) Theprogramme for in-service inspection maintenance and condition monitoring shall be based on informationgained through preceding programmes and new knowledge regarding the application of new analysistechniques and methods within condition monitoring and maintenance As such the programme shall besubjected to periodic review and possible revision as new techniques methods or data become available Theintervals may also be altered on the same basis

A 600 Inspection and condition monitoring milestones and intervals

601 Accumulated historical inspection data experiences gained from similar structures together with thoroughknowledge based on concrete design and technology ie deterioration processes etc form the basis for definingnecessary inspection and condition monitoring intervals The extent of work effort on inspection and conditionmonitoring shall be sufficient to provide a proper basis for assessing structural integrity and thereby the safetyfor the personnel involved with respect to defined acceptable risks and consequences of failure

602 An early inspection to verify that the structure has no obvious defects shall be carried out soon afterinstallation The inspection activities and the assessment shall be carried out during the first year of operationThis initial inspection shall be comprehensive and thorough and shall address all major structural elements603 During in-service more information will become available and the knowledge about the initial conditioncan be updated604 Inspection and condition monitoring of the structure shall be carried out regularly in accordance with theprogramme for inspection and condition monitoring established605 Assessment of the condition shall be carried out following the inspection activities A summaryevaluation shall be prepared at the end of each programme for inspection and condition monitoring period asoutlined in A700 The data gathered from each periodic inspection shall be compared to data gathered fromprevious inspections Evaluations shall consider not only new information but also data trends that mightindicate time-dependent deterioration processes606 Inspection and condition monitoring should be conducted after direct exposure to a design environmentalevent (eg wave earthquake etc) Special inspection following a design environmental event shall encompassthe critical areas of the structure Special inspections following accidental events may in certain circumstancesbe limited to the local area of damage Inspection should also be conducted after severe accidental loading (egboat collision failing object etc)

607 In the event of change of use lifetime extension modifications deferred abandonment damages ordeterioration of the structure or a notable change in the reliability data on which the inspection scheme is basedmeasures should be taken to maintain the structural integrity appropriate to the circumstances The programmeshall be reviewed to determine the applicability to the changed conditions and shall be subjected tomodification as required Risk to the environment shall be included

608 Based on a removal programme an assessment of the structural integrity may be carried out prior toremoval The need to complete this assessment and the extent of the assessment and inspection required willdepend heavily on the period which has elapsed since the last periodic or special inspection As a minimumhowever this assessment needs only consider safety of personnel

A 700 Documentation

701 The efficiency and integrity of the inspection and condition monitoring activities is dependent on thevalidity timeliness extent and accuracy of the available inspection data

702 To facilitate periodic inspection as specified in the programme for inspection and condition monitoringthe following documentsinformation shall be recorded

mdash Data from the design construction and installation phase (Summary Report)mdash Basic information about each inspection performed (eg basic scope of work important results available

reports and documentation)

703 Up-to-date summary inspections shall be retained by the owneroperator Such records shall describe thefollowing

mdash Toolstechniques employedmdash Actual scope of work (including any field changes)mdash Inspection data collected including photographs measurements video-recordingsmdash Inspection findings including thorough descriptions and documentation of any anomalies discovered

Any repairs and in-service evaluations of the structure shall be documented and retained by the owneroperator

A 800 Important items related to inspection and condition monitoring

801 Inspection of concrete offshore installations normally includes a survey of the different parts of thestructure including the atmospheric zone the splash and the tidal zones and the large amounts of immersedconcrete It is generally recognized that the splash zone is the most vulnerable to corrosion The submergedzone is also recognized as important because most of the structure is underwater

802 Inspection activities therefore will most often seek to identify symptoms and tell-tale signs madeevident on the surface originating from the defect ie often at a relatively advanced stage of defect progressionIn many cases it is assumed that signs of damage will be obvious before the integrity of the structure isimpaired but it should not be assumed that this always is the case

803 Essential elements of a successful condition monitoring programme include the following

mdash It is focused on areas of high damage probability and areas critical to safetymdash It is well documentedmdash It is completed at the specified intervals as a minimummdash It is repetitive to enhance training of assigned personnel

Guidance noteIt is also important to differentiate between the extent of assessment and frequency for inspection for differentstructural elements The function of each structural element will play a role in establishing the extent and frequencyof assessment The exposure or vulnerability to damage of each element shall be considered when establishingpriorities for assessment The accessibility for assessment may also be highly variable The atmospheric zone providesthe least difficult access while the submerged zone the most However the splash zone may provide the most severeenvironmental exposure and a greater likelihood of accidental impact for many concrete marine structures Thereforethe condition monitoring plan shall consider the function of each structural element and provides further considerationof element access and exposure Focusing on critical structural elements located in high exposure areas of the structurelead to efficiency in monitoring

804 Inspection and condition monitoring of the atmospheric zone should focus on detecting possible damageor defects caused by

mdash structural design and construction imperfectionsmdash environmental loadsmdash mechanical loadsmdash static and dynamic operational loadsmdash altered operational conditionsmdash chloride ingressmdash geometric anomalies such as construction joints penetrations embedmentsmdash subsidencemdash impact loads

Typical defects will be

mdash deformationstructural imperfectionsmdash cracksmdash reinforcement corrosionmdash damaged coatingsmdash freezethaw damagemdash spalls and de-laminationsmdash local impact damage

805 In addition to the aspects listed for the atmospheric zone the inspection and condition monitoring of thesplash zone should focus on

mdash effects due to alternating wetting and drying of the surfacemdash marine growth

806 In addition to the aspects listed for the atmospheric and splash zones the inspection and conditionmonitoring of the submerged zone should focus on

mdash scouring of the seabed under or in the immediate vicinity of the installation or build-up of seabed substancesediments

mdash build-up of substancesediments if such build-up covers significant parts of the structuremdash current conditionsmdash movement in bottom sedimentsmdash mechanical loadsmdash tension cable anchor pointsmdash debrismdash settlementmdash cathodic protection system (anodes)

807 The inspection of the internal parts shall focus especially on

mdash detecting any leakagemdash biological activitymdash temperature composition of seawater and pH values in connection with oil storagemdash detecting any reinforcement corrosionmdash concrete cracking

The presence of bacterial activity such as sulphate reducing bacteria (SRB) and pH shall be evaluatedconsidering the quality and thickness of the concrete cover Necessary actions against possible harmful effectof bacterial activity shall be evaluated808 Concrete durability is an important aspect concerning structural integrity and shall be assessed duringthe lifetime of the structure Important factors to assess are

mdash Those factors that are important but are unlikely to change significantly with time such as permeability andcover to reinforcement

mdash Those factors that will change with time and need to be assessed regularly such as chloride profileschemical attacks abrasion depth freezethaw deterioration and sulphate attack especially in petroleumstorage area

809 Chloride profiles should be measured in order to establish the rate of chloride ingress through theconcrete cover Either total chloride ion content or water-soluble chloride content should be measuredHowever the method chosen should be consistent throughout the life of the structure These profiles can beused for estimating the time to initiation of reinforcement corrosion attack in the structure

A 900 Corrosion protection901 Periodic examination with measurements shall be carried out to verify that the cathodic protectionsystem is functioning within its design parameters and to establish the extent of material depletion902 As far as cathodic protection (or impressed current) is utilized for the protection of steel crucial to thestructural integrity of the concrete the sustained adequate potential shall be monitored Examination shall beconcentrated in areas with high or cyclic stress utilization which need to be monitored and checked against thedesign basis Heavy unexpected usage of anodes should be investigated903 Inspection of coatings and linings is normally performed by visual inspection and has the objective toassess needs for maintenance (ie repairs) A close visual examination will also disclose any areas wherecoating degradation has allowed corrosion to develop to a degree requiring repair or replacement of structuralor piping components904 Inspection of corrosion control based on use of corrosion resistant materials can be integrated with visualinspection of the structural or mechanical components associated with such materials

Guidance noteOne of the main objectives of an inspection is to detect any corrosion of the reinforcement Several techniques havebeen developed for the detection of corrosion in the reinforcement in land-based structures These are mainly basedon electro potential mapping for which there is an ASTM standard Since the corrosion process is the result of anelectrochemical cell measurements of the electro potential of the reinforcement can provide some indication ofcorrosion activity These techniques are useful for detecting potential corrosion in and above the splash zone but havelimited application underwater because of the low resistance of seawater

905 It has been established that under many circumstances underwater corrosion of the reinforcement doesnot lead to spalling and rust staining The corrosion products are of a different form and can be washed awayfrom cracks leaving no evidence on the surface of the concrete of buried corrosion of the reinforcementHowever when the reinforcement is adequately cathodic protected any corrosion should be prevented In caseswhere cathodic protection of the reinforcement can be limited the absence of spalling and rust staining atcracks in the concrete cover should not be taken as evidence for no corrosion

A 1000 Inspection and condition monitoring types

1001 The extent and choice of methods may vary depending on the location and function of the actualstructurestructural part In the choice of inspection methods due consideration shall be taken to reduce the riskassociated with the inspection activity itself The main techniques for use underwater depend on visualinspection either by divers or by ROVs In some cases it is necessary to clean off marine growth to examinepotential defects in more detail1002 The methods shall be chosen with a focus on discovering serious damage or defects on the structuresThe methods shall reveal results suitable for detection and characteristic description of any damagedefectAreas with limited accessibility should preferably be monitored through instrumentation

1003 The following type of inspection shall be considered

a) Global visual inspectionGlobal visual inspection is an examination of the total structure to detect obvious or extensive damage suchas impact damage wide cracks settlements tilting etc The inspection can be performed at a distancewithout direct access to the inspected areas for instance by use of binoculars Prior cleaning of inspectionitem is not needed The inspection should include a survey to determine if the structure is suffering fromuniform or differential settlement

b) Close visual inspectionClose visual inspection is a visual examination of specific surface area structural part or total structure todetect incipient or minor damage The inspection method requires direct access to the inspected area Priorcleaning of the inspected item might be needed

c) Non-destructive inspectiontestingNon-destructive inspectiontesting is a close inspection by electrical electrochemical or other methods todetect hidden damage The inspection method requires direct access to the inspected area Prior cleaning ofthe inspection item is normally required

d) Destructive testingDestructive testing is an examination by destructive methods such as core drilling to detect hidden damageor to assess the mechanical strength or parameters influencing concrete durability

e) Instrumentation based condition monitoring (IBCM)In areas with limited accessibility or for monitoring of load effects corrosion development etc additionalinformation can be provided by use of instrumentation based condition monitoring The instrumentationcan be temporary or permanent Sensors shall preferably be fitted during fabrication The sensors will besuch as strain gauges pressure sensors accelerometers corrosion probes etc

1004 The structure may be instrumental in order to record data relevant to pore pressure earth pressuresettlements subsidence dynamic motions strain inclination reinforcement corrosion temperature in oilstorage etc

1005 In the case where the structure is equipped with active systems which are important to the structuralintegrity eg pore pressure water pressure under the base drawdown (reduced water level internally in thestructure to increase the external hydrostatic prestressing of the structural member) in case of storms etc thesemonitoring systems shall be inspected regularly

A 1100 Marking

1101 A marking system shall be established to facilitate ease of identification of significant items for laterinspection The extent of marking should take account of the nature of the deterioration to which the structureis likely to be subjected and of the regions in which defects are most prone to occur and of parts of the structureknown to become or have been highly utilized Marking should also be considered for areas suspected to bedamaged and with known significant repairs The identification system should preferably be devised during thedesign phase In choosing a marking system consideration should be given to using materials less prone toattract marine growth and fouling

A 1200 Guidance for inspection of special areas

1201 Poor quality concrete or concrete containing construction imperfections should be identified duringthe initial condition assessment and monitored for subsequent deterioration Surface imperfections ofparticular importance include poorly consolidated concrete and rock pockets spalls de-laminations andsurface corrosion staining

1202 The emphasis for the monitoring will be to detect and monitor damage caused by overstressingabrasion impact damage and environmental exposure

1203 Overstressing is often evidenced by cracking spalling concrete crushing and permanent distortion ofstructural members Not all cracking is the result of structural overload Some cracking can be the result ofcreep restrained drying shrinkage plastic drying shrinkage finishing thermal fluctuations and thermalgradients through the member thickness Creep and restrained shrinkage cracks commonly penetrate

completely through a structural member but are not the result of overload Plastic drying shrinkage andfinishing cracks commonly do not penetrate completely through a member and are also not load related

1204 Non-characteristic cracking pattern Whenever possible inspectors should be familiar withcharacteristic cracking patterns that are associated with loading A second distinction that should be made iswhether the observed cracks are ldquoactiverdquo or ldquopassiverdquo Active cracks are those that change in width and lengthas loads or deformation occur Passive cracks are benign in that they do not increase in severity with timeSection 5 provides guidance on critical crack widths that signal concern for the ingress of chloride ions and theresulting corrosion of embedded reinforced steel Active cracks and load or deformation-induced cracks shouldbe investigated regardless of crack width The investigation should identify the cause or causes the changeswith time and the likely effect on the structure

1205 Concrete crushing spalling and de-lamination also require careful determination of cause Crushing isgenerally associated with either flexural overload axial compression or impact Delamination and spalling canbe either load related or caused by severe corrosion of embedded reinforced steel The appropriate repairmethod for these distress types will vary considerably depending upon the actual distress cause

1206 The interface being the main load transfer point between the steel super-structure and the concretesupport should preferably be examined for structural integrity annually The examination should include theload transfer mechanism (flexible joints rubber bearings bolts and cover) and the associated ring beam

The concrete interface should be inspected for evidence of overstress and corrosion of embedded reinforcementsteel Corrosion potential surveys can be used to detect ongoing corrosion that is not visible by visual inspectionalone

1207 Construction joints in the concrete structure represent potential structural discontinuities Waterleakage and reinforcement corrosion are possible negative effects Construction joints should be located remotefrom locations of high stress and high fatigue cycling However achieving these recommendations is notalways possible As a minimum the monitoring program should identify construction joints located in highstress areas and monitor the performance with respect to evidence of

mdash leakagemdash corrosion stainingmdash local spalling at joint faces which indicate relative movement at the jointmdash evidence of poorly placed and compacted concrete such as rock pockets and de-laminationsmdash joint cracking or separation

1208 Penetrations are by their nature areas of discontinuity and are prone to water ingress and spalling atthe steelconcrete interface Penetrations added to the structure during the operational phase are particularsusceptible to leakage resulting from difficulties in achieving high quality consolidation of the concrete in theimmediate vicinity of the added penetration All penetrations in the splash and submerged zones will requirefrequent inspections

1209 Vertical intersections between different structural parts A representative sample chosen to coincidewith the highest stressfatigue utilization as obtained from analysis should be inspected Areas with knowndefects should be considered for more frequent examination The significance of cracks in these areas on thestructural integrity is substantial and emphasises the need for frequent crack monitoring for dynamic movementand length and width increases

1210 Embedment plates may constitute a path for galvanic corrosion to the underlying steel reinforcementMain concerns are corrosion and spalling around the plates Galvanic corrosion is especially severe wheredissimilar metals are in a marine environment and may lead to deterioration of the reinforcing steel which isin contact with the embedments

1211 Repair areas and areas of inferior construction These areas need to be individually assessed on theextent and method of repair and their criticality Particular concern may be associated with areas that providea permeable path through which salt-water flow can take place Continuous flow of saline and oxygenatedwater can cause corrosion of the reinforcement and washout of cementitious paste with an ensuing weakeningeffect of the reinforced concrete matrix In such areas adequate emphasis needs to be placed on the detectionof local loss of reinforcement section due to chloride induced (black) corrosion Attention should be placed onthe surface and the perimeter of patched areas for evidence of shrinkage cracking and loss of bond to the parentconcrete surface

1212 The splash zone can experience damage from impact of supply vessels etc and can also deterioratefrom ice formation with ensuing spalling in surface cavities where concrete has been poorly compacted

Even where high quality concrete was placed originally the splash zone is susceptible to early deterioration asa result of ice abrasion and freeze-thaw cycling Both distress mechanisms result in loss of surface concretewith subsequent loss of cover over the reinforcement steel For structures designed for lateral loads resultingfrom the movement of pack ice relative to the structure the heavily abraded concrete surface can cause anincrease in applied global lateral loads Repairs to these surfaces should be made as soon as possible to preventfurther deterioration and structural overload

1213 Debris Drill cuttings can build up on the cell tops andor against the side of the structure and should beassessed for

mdash lateral pressures exerted by the cuttingsmdash whether they cause an obstruction to inspection

Removal of drill cuttings needs to be assessed accordinglyDebris can cause structural damage through impact abrasion or by accelerating the depletion of cathodicprotection systems Also it poses a danger to diving activities and precludes examination if allowed toaccumulate Particular vigil needs to be maintained for impact damage covered by debris1214 Scour is the loss of foundation supporting soil material and can be induced by current accelerationround the base of the structure or by ldquopumpingrdquo effects caused by wave induced dynamic rocking motion Itcan lead to partial loss of base support and ensuring unfavourable redistribution of loads1215 Differential hydrostatic pressure (drawdown) Structural damage or equipment failure can lead toingress of water and affect the hydrostatic differential pressure (see A1005) This might call for specialinspection before and during drawdown1216 Temperature of oil sent to storage Continuous records of the temperature of the oil sent to storageshould be examined for compliance with design limitsIn cases where differential temperatures have exceeded design limits following an analysis of the additionalloading special inspections might be required1217 Sulphate reducing bacteria (SRB) SRBs occur in anaerobic conditions where organic material ispresent (such as hydrocarbons) The bacteria produce as their natural waste H2S (Hydrogen sulphide) whichin large enough amounts will cause a lowering of pH value of the cement paste in the concrete Favourableconditions for SRB growth might be present in un-aerated water in for example the water filled portion of shaftsand cells An acidic environment can cause concrete softening and corrosion of reinforcement An inspectionof the concrete surface which is likely to be affected by SRB activity is difficult to undertake Some guidancecan be obtained by adequate monitoring of SRB activity and pH levels1218 Post-tensioning Tendons are usually contained within ducts which are grouted Inspection of tendonsis therefore very difficult using conventional inspection techniques

Guidance noteSome problems with inadequate protection of tendons have been found through water leakage at anchorage points indry shafts Partial loss of prestress in tendons is generally recognised as local concrete cracking resulting fromredistribution of stress and should be investigated upon discovery Total loss of prestress can result in membercollapse Design documents should be reviewed to establish the arrangement and distribution of cracking that couldbe expected to result from partial loss of prestress This information should be documented with the inspection recordsand made available to the inspection teamPost-tensioning anchorage zones are commonly areas of complex stress patterns Because of this considerableadditional reinforcement steel is used to control cracking In many cases the reinforcing steel is very congested andthis condition can lead to poor compaction of concrete immediately adjacent to the anchorage Also the anchoragesfor the post-tensioning tendons are generally terminated in prestressing pockets in the structure and the recess is fullygrouted after tensioning and before launchExperience has also shown that the anchorage zones are prone to distress in the form of localized cracking and spallingof anchorage pocket grout materials These conditions expose the critical tendon anchors to the marine environmentcausing corrosion of the anchor and additional spalling and delamination of concrete and grout in the anchorage zoneRegular visual inspection of the anchorages is recommended Should evidence exist for potential distress a moredetailed visual inspection supplemented by impact sounding for de-laminations should be completed to determine ifthe anchorage is distressed The visual inspection should focus on corrosion staining cracking and largeaccumulations of efflorescence deposit

SECTION 9CERTIFICATION AND CLASSIFICATION

A General

A 100 Application 101 As well as representing DNVrsquos recommendations on safe engineering practice for general use by theoffshore industry the offshore standards also provide the technical basis for DNV classification certificationand verification services of offshore structures and relevant materials

A 200 Certification and classification principles201 Certification and classification of concrete structures and materials shall be based on the following mainactivities where applicable

mdash design verificationmdash independent parallel calculationsmdash survey of material testingmdash survey of manufacturing facilitiesmdash construction follow-up to verify workmanship and on-site QC controlsmdash periodical operational surveys

202 When DNV is certifying Material and Product Certificates shall be termed NV certificates See A501

A 300 Assumptions301 Any deviations exceptions and modifications to the requirements of testing or design codes andstandards shall be documented and agreed in advance with the Society302 Any applied aspects of the design and construction provisions of this standard shall be speciallyconsidered and agreed upon and their application shall be subject to DNV approval when the standard is usedfor certification or classification purposes303 DNV may accept alternative solutions found to represent a minimum safety level equivalent to that statedin the requirements of this standard

A 400 Documentation requirements401 Documentation requirements for certification services shall be in accordance with Appendix F orAppendix H for material certification and with Section 3 for structures402 Documentation requirements for classification services shall be in accordance with the NPS DocReq(DNV Nauticus Production System for documentation requirements) and DNV-RP-A201

A 500 Certificate types501 DNV defines three levels of documentation depending on importance of equipment or materials andexperience gained during serviceTest report (TR) is a document signed by the manufacturer which states

mdash conformity with the rule requirementsmdash that testing is carried out on samples from the current production of equal products

The manufacturer shall have a quality system that is suitable for the kind of certified product The surveyorshall check that the most important elements of this quality system are implemented and may carry out randominspection at any time The products shall be marked to be traceable to the test reportWorks Certificate (W) is a document signed by the manufacturer which states

mdash conformity with the rule or standard requirementsmdash that the tests are carried out on the certified product itselfmdash that the tests are made on samples taken from the certified product itselfmdash that the tests are witnessed and signed by a qualified department

The manufacturer shall have a quality system that is suitable for the kind of certified product The surveyorshall check that the most important elements of this quality system are implemented and may carry out randominspections at any time The component shall be marked to be traceable to the work certificateDNV ProductMaterial Certificate (NV) is a document signed by a DNV surveyor which states

mdash conformity with the rule requirementsmdash that the tests are carried out on the certified product itself

mdash that the tests are made on samples taken from the certified product itselfmdash that the tests are made in the presence of a DNV surveyor or in accordance with special agreements

The product or labelling as applicable shall be stamped with a special NV-stamp traceable to the certificate

A 600 Requirements to Certification601 Materials and products are categorised based on safety and complexity considerations The category ofsuch will determine the scope of the certification activity and the certificate type to be issued The level ofcertification required within this standard for the various materials and products is summarised below

B Classification of Offshore Structures

B 100 General101 DNV may class an offshore concrete structure when designed constructed and periodically surveyed inaccordance with Sections 1 to 8 inclusive of this standard

B 200 Materials201 Material requirement shall be in accordance with Section 4 of this standard

B 300 Certification of materials301 Certificate requirements for various materials are specified in A601302 Certification of concretes lightweight concretes grouts and equivalent materials with and without fibresas well as their constituents shall be based on material testing where chemical composition mechanicalproperties and other specified requirements shall be in accordance with the general requirements of E and otherapproved specifications

Table A1 Required levels of certificate

Material Product Reference in Standard Test Report (TR)Works

Certificate(W)

MaterialProduct

Certificate(NV)

Grout (incl pre-packed blended and neat cement grouts) Sec4 E100 X

Cement1 Sec4 B200 XAggregates1 Sec4 B400 and B500 XAdditions1 Sec4 B600 XAdmixtures1 Sec4 B700 XSteel Reinforcement Sec4 G100 XMechanical splices Sec4 G200 XEnd anchorages for steel reinforcement Sec4 G200 X

Prestressing Steel Sec4 H100 XComponents for Prestressing System2 Sec4 H200 X

FRP reinforcement inc prestressing Sec4 I100 and I300 XEnd anchorages for FRP reinforcement Sec4 I200 X

Concretes lightweight concretes grouts and equivalent materials with and without fibres for use as main structural material in DNV Classed Concrete Barges

Rules for Classification of Ships Pt5 Ch7 Sec14

ldquoConcrete Bargesrdquo X

Notes

1) Certificates required of constituent materials as part of the grout certification scheme see E or for materials forming the constituents for concrete to be applied in DNV classified concrete structures

2) Tendons (wires strands bars) anchorage devices couplers and ducts or sheaths are part of a prestressing system

C Classification of Concrete Barges

C 100 General

101 This standard shall be used for the design and specification of concrete barges for classification inaccordance with Rules for Classification of Ships Pt5 Ch7 Sec14 ldquoConcrete Bargerdquo

C 200 Materials

201 Material requirement shall be in accordance with Section 4 of this standard

C 300 Certification of materials

301 Certificate requirements for various materials are specified in A601

302 Certification of concretes lightweight concretes grouts and equivalent materials with and without fibresas well as their constituents shall be based on material testing where chemical composition mechanicalproperties and other specified requirements shall be in accordance with the general requirements of E and otherapproved specifications

D Certification of FRP Reinforcement (NV)D 100 General

101 This section provides the basis for certification of FRP reinforcement bars

102 For novel materials intended for use as FRP reinforcement or in the case of a known material intendedfor application in a novel or unproven way a supplementary risk based Technology Qualification shall beperformed This may be conducted in accordance with DNV-OSS-401 Technology QualificationManagement

103 Product and Material certification based on this standard shall include the following three main elements

mdash Witnessed material testing and inspection of the individual materials see Appendix Fmdash Review of relevant documentation mdash Survey and review of the Manufacturing site and QA QC procedures see Appendix G

D 200 Material testing

201 The objective of the testing and inspection during certification is to verify and document design relatedproperties of the bars to allow those properties to be applied in design in accordance with this standard

202 It is important that prior to the testing the manufacturer provides DNV with the proposed test programmeand any other relevant technical data for review and approval

203 The products covered by the testing will have their properties defined for the purpose of design inaccordance with this standard based on these test results

204 The testing of the product shall be carried out on representative test pieces from sample products to theextent described in Appendix F

205 Testing shall only be conducted in or under the coordination of the DNV laboratory

206 If testing is proposed in another facility than the DNV laboratory both the facility and proposed testmethods shall be subject to DNV approval prior to testing This approval may require testing of the proposedmethods at the DNV laboratory and or attendance during the actual testing programme by DNV laboratorypersonnel

207 During the testing programme the DNV surveyor shall witness a proportion of the testing as required bythis standard and approved specifications

D 300 Manufacturing site approval

301 The manufacturing sitersquos QA QC procedures shall be reviewed by DNV as part of the certificationprocess see Appendix G

302 The production site referenced on the product certificate shall be subject to an initial audit and a recurringperiodical survey scheme both of which shall be performed by DNV

Guidance noteTo assess the required scope of the survey scheme to suit the plant and operations of each particular manufacturer theDNV bottom-up audit system ldquoManufacturer Product Quality Assessment (MPQA)rdquo may be applied

303 In order to carry out the required surveys the DNV surveyor shall at any time upon request be givenaccess to all areas and facilities for production and quality control at the manufacturing facility

304 Periodical surveys of the manufacturing plant shall be conducted by the DNV surveyor after the awardof the certificate to ensure the agreed QA QC are being satisfactorily implemented The frequency of timingof these surveys shall be confirmed in advance with the manufacturer

305 When the manufacturing and production of the products has been found acceptable a ManufacturingSurvey Arrangement (MSA) can be agreed between the local DNV office and the manufacturer

306 The certification of the materials will in such cases be carried out as agreed in the MSA

D 400 Award of certificate

401 When compliance with the requirements is confirmed a Product Certificate shall be issued and validatedby DNV

402 The Product being certified shall be marked for traceability to the certificate as required and advised byAppendix G

D 500 Maintenance of certificate

501 Product certificates shall have a validity of 5 years from the date of issue

502 The maintenance of a Product Certificate is dependent on the upkeep of a current manufacturing plantsurvey scheme to be performed by DNV including periodical surveys

503 DNV may at any time require to visit and inspect any manufacturing facility currently producing aproduct under DNV certification

E Certification of Structural Grout (NV)E 100 General

101 This standard provides the basis for certification of structural grout (hereafter referred to as grout) orequivalent material

102 The certification scheme for grout shall include the following main elements

mdash Witnessed material testing and inspection of the testing facilities see Appendix Hmdash Review of relevant documentation including grouting procedures qualification scheme for third party

grouting contractors as well as on-site QC procedures see Appendix H mdash Witnessed mock-up testing to verify the suitability of the material method and equipment to be used on-

sitemdash Production plant survey and review of QA QC procedures see Appendix I

103 Documentation relevant to the application of the material shall be submitted and approved by DNVGeneric grouting procedures as well as specifications for qualifying third party grouting contractors shall besubmitted Quality control documents relevant for the casting curing transporting and testing of site cast QCsamples shall also be reviewed and approved

104 DNV shall not under normal circumstances approve the addition of admixtures or fibres on-site to acertified product

E 200 Material testing

201 The objective of the witnessed material testing shall be to verify and document design related propertiesof the grout to allow those properties to be applied in design in accordance with this standard

202 Material testing shall be conducted in an independent testing laboratory holding ISO 17025 or similaraccreditation as well as ISO 9001 certification

204 The grout products covered by the testing will have their properties defined for the purpose of design inaccordance with this standard based on the witnessed test programme

205 Material testing for pre-packed blended grout shall be carried out on representative specimens fromsample products to the extent described in Appendix H B100 to B200

206 Material testing for neat cement grout shall be carried out on representative specimens from sampleproducts The extent and method of testing shall be agreed upon in advance with the Society

207 During the testing programme the DNV surveyors shall witness a proportion of the testing as requiredby this standard and approved specifications

Guidance noteDNV will witness a number of tests carried out during the execution of the test programme Extra emphasis isnormally placed in the beginning of the test programme when the fresh grout properties are to be tested and to ensure

that the samples for testing the hardened grout properties are prepared and stored according to the approved testprogramme Based on this as a minimum the following attendance may be taken as a guide

For the testing of fresh grout properties

DNV surveyor witness one complete series of tests (test identification FG1-FG5 in Appendix H) carried out todocument the fresh grout properties ie tests for flowability density segregation bleeding air content and settingtime for one batch

For the testing of hardened grout properties

DNV surveyors witness preparation and subsequent storing of all test specimens for documenting the hardened groutproperties

DNV surveyors witness at least one occurrence of each specified test ideally the first set of tests carried out for eachparameter (test identification HG1-HG7 in Appendix H) to document the hardened grout properties ie tests forcompressive strength (cylinderscubes) flexural strength creep autogenous shrinkage total shrinkage expansionproperties Youngs modulus and Poissons Ratio

The final selection of tests to be witnessed will be agreed upon in advance with the manufacturer

208 The testing programme described in Appendix H B100 qualifies the grout for normal applicationbetween a minimum application temperature tapp min and an upper limit tapp max For normal applicationtapp min is taken as 5degC and tapp max as 30degC

209 For grout material intended for application below 5degC the minimum test temperature ttest min shall bederived from the minimum application temperature tapp min minus a constant ηtemp to account for variabilityin the conditioning testing and curing temperatures during the testing programme This also provides a levelof safety on operations against the inherent inaccuracies of temperature forecasting and recording offshoreduring application of the material

ttest min = tapp min - ηtemp

where

ηtemp = 1degC for normal control conditions

E 300 Approval of supporting documentation and mock up testing

301 See Appendix H C100 for a complete list of required documentation

302 Grouting procedures in generic form for each proposed application shall be subject to approval byDNV

303 Witnessed mock up testing shall be conducted to verify the suitability of the material and the proposedgrouting arrangement corresponding to each grouting procedure The requirements for the mock up test willvary depending on the material and proposed application

304 Material testing of the fresh and hardened properties of the grout shall be conducted during the mock uptesting The requirements for material tests will vary depending on the material and application

305 Documentation pertaining to the proposed on-site QC regime shall be subject to approval by DNV Therequirements for on-site QC testing will depend on the material in question and the level of control during itsmanufacture In the case of neat cement grout a higher level of on-site control will be required than for pre-packed blended grout

E 400 Manufacturing site approval

401 This section applies to manufacturing plants for the production of pre-packed blended grout

402 The manufacturing sites QA QC procedures shall be approved by DNV as part of the certificationprocess see Appendix I

403 Each production site referenced on the material certificate shall be subject to an initial audit and arecurring periodical survey scheme both of which shall be performed by DNV

Guidance note

To assess the required scope of the survey scheme to suit the plant and operations of each particular manufacturer theDNV bottom-up audit system ldquoManufacturer Product Quality Assessment (MPQA)rdquo may be applied

404 If more than one production site is to be quoted on the material certificate or if the source of cementaggregate or admixtures changes (and that change necessitates a modification to the grout mix formulation design) the manufacturer shall verify by testing that the produced grout meets the chemical and physicalproperties defined during the witnessed material testing

Guidance noteIt is the intent of the standard that only grout produced from one manufacturing location be subject to the full rangeof witnessed material testing Grout produced in additional locations shall be subject to verification testing to proveconsistency of properties

405 Testing to verify the consistency of material produced in additional production sites shall be carried outat an independent laboratory meeting the requirements of E202 Documented evidence of the results shall besubject to review by DNV406 DNV shall witness a representative sample of normal internal QC testing at each production site prior tothe approval of that site407 In order to carry out the required inspections and surveys the DNV surveyor shall at any time uponrequest be given access to all areas and facilities for production and quality control at the manufacturingfacility408 Periodical surveys of the manufacturing plant shall be conducted by the DNV surveyor after the awardof the certificate to ensure the agreed QA QC procedures are being satisfactorily implemented The frequencyof timing of these surveys shall be confirmed in advance with the manufacturer409 When the manufacturing and production of the certified material has been found acceptable aManufacturing Survey Arrangement (MSA) can be agreed between the local DNV office and the manufacturerThe certification of the materials will in such cases be carried out as agreed in the MSA

E 500 Award of certificate501 When compliance with the requirements is confirmed a Material Certificate shall be issued and validated byDNV502 The labels bags andor data sheet of the certified material shall be marked for traceability to thecertificate as required and advised in Appendix I

E 600 Maintenance of certificate601 Material certificates shall have a validity of 5 years from the date of issue602 The maintenance of a material certificate is dependent on the upkeep of a current manufacturing plantsurvey scheme to be performed by DNV including periodical surveys 603 DNV may at any time require to visit and inspect any manufacturing facility currently producing amaterial under DNV certification

Offshore Standard DNV-OS-C502 September 2012 AppA ndash Page 165

APPENDIX A ENVIRONMENTAL LOADING (GUIDELINES)

A General

A 100 Environmental Loads

101 Wind wave tide and current are important sources of environmental loads (E) on many structureslocated offshore In addition depending on location earthquake or ice loads or both can be significantenvironmental loads

102 Loads from wind wave and current occur by various mechanisms The most important sources of loadare

mdash Viscous or drag effects generally of most importance for relatively slender bodiesmdash Inviscid effects due to inertia and wave diffraction These are generally of most importance in terms of

global effects for relatively large volume bodies

103 For fixed concrete structures static analyses can be adequate The possibility that dynamic analysis isrequired on local components or on the global platform shall be investigated In the specific case of waveloading the possibility that non-linear effects can lead to loads at frequencies either above or below thefrequency range in the wave spectrum both during temporary floating conditions and at the permanent locationshall be investigated Potential dynamic effects on local or global loads from wave wind and current sourcesshall also be investigated

104 The influence of the structure on the instantaneous water surface elevation shall be investigated Possibledirect impact of green-water on a deck or shafts shall also be investigated Total water surface elevationdepends on storm surge and tide the crest height of incident waves and the interaction of the incident waveswith the structure or other adjacent structures

105 Environmental loads due to wind wave and current relate particularly to the ultimate limit staterequirements In addition these loads can contribute to the fatigue serviceability and accidental limit statesEnvironmental loads due to wind wave and current shall also be considered in temporary configurations of thestructure during construction tow and installation

106 The estimation of loads due to wind wave and current requires an appropriate description of the physicalenvironment in the form of sea state magnitude and direction associated wind magnitude and direction andrelevant current descriptions in terms of current velocity profiles through the depth and associated directionalinformation The derivation of wind wave and current combinations required for calculation of loads isdescribed in DNV-OS-101 Section 3

107 Procedures for the estimation of seismic loads are provided in DNV-OS-C101 Section 3

108 The computation of ice loads is highly specialized and location dependent and is not covered in detailedby this Standard There is an extensive relevant body of literature available for the computation of ice loadsthat should be consulted for guidance Ice loads shall be computed by skilled personnel with appropriateknowledge in the physical ice environment in the location under consideration and with appropriate experiencein developing loads based on this environment and the load return periods in accordance with DNV-OS-C101Section 3

A 200 Extreme wave loads

201 Wave loads from extreme conditions shall be determined by means of an appropriate analysis proceduresupplemented if required by a model test program Global loads on the structure shall be determined Inaddition local loads on various appurtenances attachments and components shall be determined

202 The appropriate analysis procedure to compute wave loads generally depends on the ratio of wavelengthto a characteristic dimension of the structure such as the diameter of a column or shafts For ratios less thanapproximately 5 a procedure such as diffraction analysis shall be applied that accounts for the interaction ofthe structure with the incident wave-field For higher ratios a slender body theory such as Morison theory maybe considered Where drag forces are important in this regime both methods should be applied in combinationIn some cases such as in the computation of local loads on various external attachments to a structure bothprocedures can be required

The length of the structure relative to wave length is also of importance for floating structures as cancellationor reinforcement effects may occur if the wave length corresponds with the length or multiple length of thestructure

203 Model testing shall be considered to supplement analytical results particularly in cases where it isanticipated that non-linear effects will be significant or where previous experience is not directly applicablebecause of the configuration of the structure

A 300 Diffraction analysis

301 Global loads on large volume bodies shall generally be estimated by applying a validated diffractionanalysis procedure In addition local kinematics required in the design of various appurtenances shall beevaluated including incident diffraction and (if necessary) radiation effects

302 The fundamental assumption is that the fluid is inviscid and that the oscillatory motions of both the wavesand of the structure are sufficiently small to permit the assumption of linearity The hydrodynamic interactionbetween waves and a prescribed structure can be predicted based on linearized three-dimensional potentialtheory

303 Analytical procedures shall be implemented generally through well-verified computer programstypically based on sourcesink (Greens Function) panel methods or similar procedures Alternative proceduresincluding classical analytical or semi-analytical methods and the finite element procedure may be consideredin specialized cases Programs should be validated by appropriate methods

304 Diffraction analysis using panel methods shall be executed with an adequate grid density to provide asolution with the required accuracy The grid density shall be sufficient to adequately capture fluctuations inparameters such as pressure In zones where the geometry changes abruptly (corners edges) denser grids shallbe employed Also in the vicinity of the free surface grid densities will generally be increased Grid densitiesshall be related to the wave period in order to provide an adequate description of fluctuations over thewavelength Six panels per wavelength are usually sufficient on a smooth surface In general convergence testswith grids of variable density shall be carried out to confirm the adequacy of any proposed panel model

305 Diffraction models shall be combined with Morison models in the assessment of various relativelyslender attachments to large volume structures Diffraction methods provide local fluid velocity andacceleration required in the Morison model Morison theory may be applied to compute resulting loads

306 The proximity of additional relatively large volume structures shall be included in assessing loadsDisturbances in the wave field around two or more structures may interact and this interaction shall beaccounted for in the analysis

307 Structures with significantly varying cross-section near the waterline within the likely wave-affectedzone call for additional consideration Non-wall sided structures are not consistent with the underlyingassumptions of linear diffraction theory and both local and global loads and load effects can be significantlynon-linear relative to the magnitude of the sea state Linear diffraction theory assumes wall-sided geometry atthe waterline

308 The calculation of wave forces on surface piercing structures that will be overtopped by the progressingwave need special attention and validation of the computing technique is necessary

309 Careful consideration shall be given to potential pressure fluctuations on the base of a platform duringthe passage of a wave field If the foundation conditions are such that pressure fluctuations are expected tooccur on the base such pressure fluctuations shall be included in the analysis

310 Diffraction analysis programs may be used to produce coefficients required in the evaluation of variousnon-linear effects typically involving sum frequency or difference frequency effects

A 400 Additional requirements for dynamic analysis under wave load

401 In cases where the structure can respond dynamically such as in the permanent configuration (fixed orfloating) during wave load or earthquakes or in temporary floating conditions additional parametersassociated with the motions of the structure shall be determined Typically these additional effects shall becaptured in terms of inertia and damping terms in the dynamic analysis

402 Ringing can control the extreme dynamic response of particular types of concrete gravity structure Aringing response resembles that generated by an impulse excitation of a linear oscillator it features a rapidbuild-up and slow decay of energy at the resonant period of the structure In high sea states ringing may beexcited by non-linear (second third and higher order) processes in the wave loading that are only a small partof the total applied environmental load on a structure

403 The effects of motions in the permanent configuration such as those occurring in an earthquake floatingstructures or in temporary phases of fixed installations during construction tow or installation on internalfluids such as ballast water in tanks shall be evaluated Such sloshing in tanks generally affects the pressuresparticularly near the free surface of the fluid

A 500 Model testing

501 The necessity of model tests to determine extreme wave loads shall be determined on a case-by-casebasis Generally model tests shall be considered when it is required to

mdash Verify analytical procedures Model tests should be executed to confirm the results of analyticalprocedures particularly in cases with structures of unusual shape structures in shallow water with steepextreme waves or in any other case where known limitations of analytical procedures are present

mdash Complement analytical procedures Model tests should be executed where various effects such as ringing

wave run up potential occurrence of deck slamming or in cases where the higher order terms neglected inanalytical procedures may be important These effects cannot usually be assessed in the basic analyticalprocedure

502 Froude scaling is considered to be appropriate for typical gravity driven processes like waves actingalone on large volume fixed structures The influence of viscosity and Reynolds number effects shall beconsidered in any decision to apply Froude scaling

503 Where possible model test loads shall be validated by comparison with analytical solutions or the resultsof prior appropriate test programs

504 Appropriate data shall be recorded in model tests to facilitate computation of wave loads Data in theform of time history recordings may include

mdash The local instantaneous airwater surface elevation at various locationsmdash Local particle kinematicsmdash Global loads such as base shear vertical load or overturning moment as well as local loads as pressure

distribution acting on individual componentsmdash Structural response such as displacements and accelerations particularly if dynamic response occurs

505 Model test data shall be converted to full scale by appropriate factors consistent with the physical scalingprocedures applied in the test program

506 It shall be recognized that analogous with analytical procedures model test results have inherentlimitations These limitations shall be considered in assessing the validity of resulting loads The primarysources of inherent limitation include

mdash Surface tension effects These are not generally allowed for in model test program definition and may besignificant particularly where large-scale factors are applied

mdash Viscous effects The Reynolds number is not generally accurately scaled and these effects are importantwhere viscosity is significant such as in the prediction of drag or damping effects

mdash Airwater mixing and entrainment Various loads that depend on this type of factor such as slamming forceswill not in general be accurately scaled in typical Froude scale based model tests

507 The influence of different effects on loads determined in model tests shall be assessed and steps taken inthe testing program to reduce or minimize them Such effects might be

mdash Wave reflections from the ends of model test basinsmdash Scattering of waves from large volume structures and reflection of spurious scattered waves from model

basin sidewalls interfering with target design wave conditionsmdash Break down of wave trains representing the target design wave due to various instabilities leading to an

inaccurate realisation of design wave conditionsmdash Difficulties in the inclusion of wind or currents in association with wave fields

A 600 Current load

601 Currents through the depth including directionality shall be combined with the design wave conditionsThe Characteristic current load shall be determined in accordance with DNV-OS-C101 Section 3

602 The disturbance in the incident current field due to the presence of the fixed structure shall be accounted for

603 Current loads on platforms shall be determined using recognized procedures Typical methods are basedon the use of empirical coefficients accounting for area shape shielding etc Such empirical coefficients shallbe validated Model tests or analytical procedures or both shall be considered to validate computed currentloads

604 Numerical procedures based on Computational Fluid Dynamics (CFD) may be considered in theevaluation of current loads or other effects associated with current These procedures are based on a numericalsolution of the exact equations of the motion of viscous fluids (the Navier Stokes equations) Only wellvalidated implementations of the CFD procedure shall be used in the computation of current effects Themethod can provide a more economic and reliable procedure for predicting drag forces than physical modellingtechniques

605 Disturbances in the incident current field lead to modifications in the local current velocity in the vicinityof the structure Loads on local attachments to the structure shall be computed based on the modified currentfield The possibility of Vortex Induced Vibrations (VIV) on various attachments shall be investigated

606 The presence of water motions in the vicinity of the base of a structure can lead to scour and sedimenttransport around the base The potential for such transport shall be investigated Typical procedures require thecomputation of fluid velocity using either CFD or model test results These velocities are generally combinedwith empirical procedures to predict scouring

607 If found necessary scour protection should be provided around the base of the structure See DNV-OS-C101 Section 11

A 700 Wind loads701 Wind loads may be determined in accordance with DNV-OS-C101 Sec3 E700702 Wind forces on an Offshore Concrete Structure will consist of two parts

mdash wind forces on topside structuremdash wind forces on concrete structure above sea level

703 The wind load on the exposed part of the Offshore Concrete Structure is normally small compared to thewind forces on the topside and to wave load effects A simplified method of applying the wind load effect tothe concrete structure is by using the wind forces derived for the topside structure These forces will contributeto the overall global loads like the overturning moment and horizontal base shear in addition to increased forcesin vertical direction of the concrete shafts704 Global mean wind loads on the exposed part of a concrete structure shall be determined based on theappropriate design wind velocity in combination with recognized calculation procedures In a typical caseglobal wind load may be estimated by simplified procedures such as a block method In this type of procedurewind loads may be based on calculations that include empirical coefficients for simple shapes for which datais available an appropriate exposed area and the square of the wind velocity normal to the exposed area Localwind loads shall generally require inclusion of a gust factor or similar considerations to account for more localvariations of wind velocities705 Global dynamic effects of wind load shall be investigated if relevant As an example a structure and itsmooring system in a temporary condition during the construction towing or installation phases can besusceptible to wind dynamics An appropriate description of wind dynamics such as a wind spectrum shall beincluded in wind load estimation706 In addition to wind wave and current loads present at the offshore site these loads shall also besystematically evaluated where relevant during construction tow and installationremoval conditions Thecomplete design life cycle of the structure from initial construction to removal shall be considered andappropriate governing design combinations of wind wave and current shall be assessed in any phase

Offshore Standard DNV-OS-C502 September 2012 AppB ndash Page 169

APPENDIX B STRUCTURAL ANALYSES ndash MODELLING (GUIDELINES)

A General

A 100 Physical representation101 Dimensions used in structural analysis calculations shall represent the structure as accurately asnecessary to produce reliable estimates of load effects Changes in significant dimensions as a result of designchanges shall be monitored both during and after the completion of an analysis Where this impacts on theaccuracy of the analysis the changes shall be incorporated by reanalysis of the structure under investigation102 It is acceptable to consider nominal sizes and dimensions of the concrete cross-section in structuralanalysis provided that tolerances are within the limits set out for the construction and appropriate materialpartial safety factors are used103 Where ldquoas-builtrdquo dimensions differ from nominal sizes by more than the permissible tolerances theeffect of this dimensional mismatch shall be incorporated into the analysis The effect of tolerances shall alsobe incorporated into the analysis where load effects and hence the structural design are particularly susceptibleto their magnitude (imperfection bending in walls implosion of shafts etc)104 Concrete cover to nominal reinforcement and positioning of prestressing cables may be provided wherethese are defined explicitly in detailed local analysis Again this is subject to construction tolerances beingwithin the specified limits and appropriate material partial safety factors being applied to component materialproperties105 The effects of wear and corrosion shall be accounted for in the analysis where significant and whereadequate measures are not provided to limit such effects106 It will normally be sufficient to consider centre-line dimensions as the support spacing for beams panelsetc Under certain circumstances however face-to-face dimensions may be permitted with suitablejustification The effect of eccentricities at connections shall be considered when evaluating local bendingmoments and stability of the supporting structure107 Material properties used in the analyses of a new design shall reflect the materials specified forconstruction For existing structures material properties may be based on statistical observations of materialstrength taken during construction or derived from core samples extracted from the concrete108 It is normally acceptable to simulate the concrete by equivalent linear elastic properties in most limitstates Unless a different value can be justified the Youngrsquos modulus of plain concrete taken as the secantvalue between σc = 0 and 04 fcck may be used as the modulus of reinforced concrete in such an analysis Thevalue used shall be in accordance with the concrete design rules in use For loads that result in very high strainrates the increase in concrete Youngrsquos modulus should be considered in the analyses of the corresponding loadeffects109 Age effects on the concrete may be included if sufficiently documented by applicable tests Effects ofload duration and resultant creep of the concrete shall also be considered where significant Where loads mayoccur over a significant period in the life of the structure the least favourable instance shall be considered indetermining age effects110 Accurate evaluation of concrete stiffness is particularly important for natural frequency or dynamicanalysis and for simulations that incorporate significant steel components such as the topsides or conductorframing Consideration shall be given to possible extreme values of concrete stiffness in such analyses Theaggregate type may influence the stiffness of the concrete and this effect shall be allocated for in the analyses111 Non-linear analysis techniques are often applied to local components of the structure It is typical todiscretely model concrete reinforcement and prestressing tendons in such simulations Where this is the caseeach material shall be represented by appropriate stress-strain behaviour using recognized constitutive models112 The density of reinforced concrete shall be calculated based on nominal sizes using the specifiedaggregate density mix design and level of reinforcement with due allowance for design growth For existingstructures such densities shall be adjusted on the basis of detailed weight reports if available Variation ineffective density through the structure shall be considered if significant113 Unless another value is shown to be more appropriate a Poissons ratio of v = 02 shall be assumed forun-cracked concrete For cracked concrete a value of v = 0 may be used A coefficient of thermal expansionof 10 times 10-5 degC shall also be used for concrete and steel in lieu of other information Where the design of theconcrete structure is particularly sensitive to these parameters they shall be specifically determined by thematerials in use Special considerations are required for concrete exposed to cryogenic temperature114 The representation of a fixed structure foundation will differ depending on the type of analysis beingundertaken For static analysis reactive pressures applied to soil contact surfaces shall be sufficient but fordynamic analysis or where soilstructure interaction is significant an elastic or inelastic representation of the

foundation should be produced to provide suitable stiffness Seismic analysis is typically very dependent onsoil properties particularly at the abnormal level earthquake (ALE)115 Reactions on the structure from its foundationanchorage shall be based on general principles of soilmechanics in accordance with DNV-OS-C101 Section 11 Sufficient reactive loads shall be applied to resisteach direction of motion of the structure (settlement rocking sliding etc) The development of hydraulicpressures in the soil that act in all directions should be considered where appropriate Consideration shall begiven to potential variation of support pressures across the base of a fixed concrete structure116 The calculations used shall reflect the uncertainties inherent in foundation engineering Upper and lowerbounds and varied patterns of foundation reaction shall be incorporated and an appropriate range of reactiveloads shall be assessed In particular the sensitivity of structural response to different assumptions concerningthe distribution of reaction between the base and any skirts shall be determined117 Consideration shall also be given to the unevenness of the seabed which can potentially cause high localreactions Foundation unevenness may be considered as a deformational load in subsequent design checksOther than this foundation pressures shall be considered as reactive loads their magnitude shall be sufficientto react all other factored loads118 Upper limits of soil resistance should be considered during analysis of platform removal119 The analyses shall include intermediate conditions such as skirt penetration and initial contact as wellas the fully grouted condition if significant Disturbance of the seabed due to the installation procedure shouldbe considered in calculating subsequent foundation pressures120 Where it significantly affects the design of components soil interaction on conductors shall also beincorporated in the analysis particularly with regard to local analysis of conductor support structures121 Other than direct support from foundation soils a component may be supported by

mdash external water pressure while floatingmdash other components of the structuremdash anchor supportsmdash any combination of the above and foundation soils

122 The load of water pressure in support of a fixed concrete structure while floating or a floating concretestructure shall be evaluated by suitable hydrostatic or hydrodynamic analysis and shall be applied toappropriate external surfaces of the structure 123 Representative boundary conditions shall be applied to the analysis of a component extracted from theglobal structure These boundary conditions shall include possible settlement or movement of these supportsbased on a previous analysis of the surrounding structure124 In the absence of such data suitable idealized restraints should be applied to the boundary of thecomponent to represent the behaviour of surrounding structure Where there is uncertainty about the effectivestiffness at the boundaries of the component a range of possible values shall be considered125 Force stiffness or displacement boundary conditions may be applied as supports to a component Wherethere is uncertainty as to which will produce the most realistic stresses a range of different boundary conditionsshall be adopted and the worst load effects chosen for design126 Where components of the structure are not fully restrained in all directions such as conductors withinguides and bearing surfaces for deck and bridge structures allowance shall be made in the analysis formovement at such interfaces

A 200 Loads201 Loads shall be determined by recognized methods taking into account the variation of loads in time andspace Such loads shall be included in the structural analysis in a realistic manner representing the magnitudedirection and time variance of such loads202 Permanent and live loads shall be based on the most likely anticipated values at the time of the analysisConsideration shall be given to minimum anticipated values as well as maximum loading The former governssome aspects of the design of gravity based structures203 Hydrostatic pressures shall be based on the specified range of fluid surface elevations and densitiesHydrostatic pressures on floating structures during operation transportation installation and removal stagesshall include the effects of pitch and roll of the structure due to intentional trim wind heel wave load or damageinstability The above also apply to fixed structures under transportation installation and removal phases204 Prestressing effects shall be applied to the model as external forces at anchorages and bends or asinternal strain compatible effects In both cases due allowance shall be made for all likely losses in prestressingforce Where approximated by external reactions relaxation in tendon forces due to the effect of other loads onthe state of strain in the concrete shall be considered205 Thermal effects are normally simulated by temperatures applied to the surface and through the thicknessof the structure Sufficient temperature conditions shall be considered to produce maximum temperature

differentials across individual sections and between adjacent components The temperatures shall bedetermined with due regard to thermal boundary conditions and material conductivity Thermal insulationeffects due to insulating concrete or drill cuttings shall be considered if present206 Wave current and wind loads shall include the influence of such loads on the motion of the structurewhile floating In cases where dynamic response of the structure may be of importance such response shall beconsidered in determining extreme load effects Pseudo-static or dynamic analyses shall be used 207 Uncertainties in topsides centre of gravity built-in forces and deformations from transfer of topsidesfrom barges to the concrete structure shall be represented by a range of likely values the structure beingchecked for the most critical extreme value208 Structures designed to contain cryogenic gas (LNG) shall additionally be designed in accordance withthe provisions made in DNV-OS-C503

A 300 Mass simulation301 A suitable representation of the mass of the structure shall be prepared for the dynamic analysis motionprediction and mass-acceleration loads while floating The mass simulation shall include relevant quantitiesfrom at least the following list

mdash All structural components both steel and concrete primary and secondarymdash The mass of all intended equipment consistent with the stage being consideredmdash The estimated mass of temporary items such as storage lay-down etcmdash Masses of any fluids contained within the structure including equipment and piping contents oil storage

LNG storage flooding etcmdash The mass of solid ballast within the structuremdash Snow and ice accumulation on the structure if significantmdash Drill cuttings or other deposits on the structuremdash The mass of marine growth and external water moving with the structuremdash Added water massmdash Added soil mass

302 The magnitudes of masses within the structure shall be distributed as accurately as necessary todetermine all significant modes of vibration (including torsional modes) (when required) or mass-accelerationeffects for the structural analysis being performed Particular attention shall be paid to the height of topsidesequipment or modules above the structural steelwork303 It is normally necessary to consider only the maximum mass associated with a given analysis conditionfor the structure For dynamic analyses however this may not produce the worst response in particular withrespect to torsional modes and a range of values of mass and centre of gravity may have to be considered Forfatigue analysis the variation in load history shall be considered If appropriate an average value over the lifeof the structure may be used In such cases it is reasonable to consider a practical level of supply and operationof the platform

NoteCalculation of the added mass of external or entrained water moving with the structure shall be based on best availablepublished information or suitable hydrodynamic analysis In lieu of such analysis this mass may be taken as the fullmass of displaced water by small-submerged members reducing to 40 of the mass of displaced water by largerstructural members Added mass effects may be ignored along the axial length of prismatic members such as theshafts

---e-n-d---of---N-o-t-e---

A 400 Damping401 Damping arises from a number of sources including structural damping material damping radiationdamping hydrodynamic damping and frictional damping between moving parts Its magnitude is dependent onthe type of analysis being performed In the absence of substantiating values obtained from existing platformmeasurements or other reliable sources a value not greater than 3 of critical damping may be used

Offshore Standard DNV-OS-C502 September 2012 AppC ndash Page 172

APPENDIX C STRUCTURAL ANALYSES (GUIDELINES)

A General

A 100 Linear elastic static analysis101 It is generally acceptable for the behaviour of a structure or component to be based on linear elastic staticanalysis unless there is a likelihood of significant dynamic or non-linear response to a given type of loadingIn such cases dynamic or non-linear analysis approaches shall be required as defined in A200 to A400102 Static analysis is always permissible where all actions on the component being considered aresubstantially invariant with time Where actions are periodic or impulsive in nature the magnitude of dynamicresponse shall be evaluated in accordance A200 and static analysis shall only be permitted when dynamiceffects are small103 Reinforced concrete is typically non-linear in its behaviour but it is generally acceptable to determineglobal load paths and sectional forces for ultimate serviceability and fatigue limit states based on anappropriate linear elastic analysis subject to the restrictions presented below Non-linear analysis is normallyrequired for accidental limit states abnormal level earthquake and local analysis104 Linear stiffness is acceptable provided that the magnitudes of all actions on the structure are notsufficient to cause significant redistribution of stresses due to localised yielding or cracking Response todeformational loads in particular is very susceptible to the level of non-linearity in the structure and shall becarefully assessed for applicability once the level of cracking in the structure is determined105 Reduction of the stiffness of components should be considered if it can be shown that due to excessivecracking for example more accurate load paths might be determined by such modelling Such reducedstiffness shall be supported by appropriate calculations or by non-linear analysis106 A linear analysis preserves equilibrium between external applied loads and internal reaction forcesLinear solutions are thus always equilibrium states The equations of a linear system need to be solved onlyonce and the solution results may be scaled to any load level A solution is hence always obtained irrespectiveof the load levels Linear analysis can be carried out for many independent load cases at the time Theindependent load cases may be superimposed into combined cases without new solution of the equation system

NotePractise has shown that the use of a system representing all actions as unit load cases that afterwards can be scaled inmagnitude and added to represent complete load combinations ie loading scenarios is very effective

---e-n-d---of---N-o-t-e---

A 200 Dynamic analysis201 Fixed structures with natural periods of the global structure greater than 25s can be susceptible todynamic response due to wave action during in-service conditions at least for fatigue assessment Structuresin shallow water or subject to extreme wave conditions may exhibit significant dynamic response at lowerperiods due to the higher frequency content of shallow water or particularly steep waves202 Other load conditions to which the structure may be subjected such as sea tow wind turbulencevibration impact and explosion can also impose dynamic forces of significant magnitude close to fundamentalperiods of the structure or its components Structures that respond to a given set of actions by resonant vibrationat one or more natural periods shall be assessed by dynamic analysis techniques203 Earthquakes are a particularly severe form of oscillatory loading that shall always require detaileddynamic analysis in moderate and high seismicity areas204 Where dynamic effects can be significant dynamic response can be evaluated on the basis of a simplifiedrepresentation of the structure or by the calculation of natural periods and the evaluation of dynamicamplification factors In evaluating dynamic amplification factors for wave loading consideration shall begiven to higher frequency components of wave and wind action that occur due to drag loading sharp crestedshallow water waves finite wave effects ringing etc205 Where substantial dynamic response of the structure is predicted having magnitude at critical sectionsexceeding that predicted by static only analysis detailed dynamic analysis shall be required Dynamic analysisshall also be required where more than one fundamental mode of the structure is significantly excited by theapplied actions as is the case for seismic response206 Where dynamic effects are relatively insignificant a pseudo-static analysis of the structure or itscomponents may be performed including dynamic effects in accordance with A300207 Where dynamic response is likely to be significant full dynamic analysis shall be performed to quantifysuch effects Appropriate mass and damping simulations shall be applied to the structure to enable the naturalmodes of vibration to be determined with accuracy

208 Dynamic analysis will normally require a linearized simulation of the soil stiffness for in-serviceconditions This stiffness shall be determined with due allowance for the expected level of loading on thefoundation Specific requirements apply for seismic analysis209 Actions applied to the structure or component shall include all frequency content likely to cause dynamicresponse in the structure The relative phasing between different actions shall be rigorously applied210 Harmonic or spectral analysis methods are suitable for most forms of periodic or random cyclic loadingWhere significant dynamic response is coupled with non-linear loading or non-linear behaviour of thestructure component or foundation then transient dynamic analysis shall be required211 Where modal superposition analysis is being performed sufficient modes to accurately simulatestructural response shall be included otherwise a form of static improvement shall be applied to ensure thatstatic effects are accurately simulated212 For impulse actions such as ship impacts slam loads and blast loading dynamic amplification effectsmay be quantified by the response of single- or multi-degree of freedom systems representing the stiffness andmass of the components being analysed Transient dynamic analysis should be provided

A 300 Pseudo-static analysis301 In this context pseudo-static analysis refers to any analysis where dynamic actions are representedapproximately by a factor on static loads or by equivalent quasi-static actions The former approach isappropriate where static and dynamic action effects give an essential similar response pattern within thestructure but differ in magnitude302 For the former approach dynamic amplification factors shall be used to factor static only response Suchfactors will in general vary throughout the structure to reflect the differing magnitudes of static and dynamicresponse For platform columns or shafts appropriate local values of bending moment should be used Baseshear overturning moment and soil pressure are representative responses for the platform base303 For the latter approach additional actions shall be applied to the structure to represent dynamic mass-acceleration and inertial effects All actions applied in a pseudo-static analysis may be considered constant overtime except in the case of non-linear response where knowledge of the load history may be significant andloading should be applied to the simulation in appropriate steps304 Factored dynamic results shall be combined with factored static effects due to gravity etc in accordancewith the limit states being checked Load partial safety factors for dynamic loads should be consistent with theloading that causes the dynamic response normally environmental The most detrimental magnitude anddirection of dynamic loading shall be considered in design combinations

A 400 Non-linear analysis401 Non-linear behaviour shall be considered in structural analysis when determining action effects in thefollowing cases

mdash Where significant regions of cracking occur in a structure such that global load paths are affectedmdash Where such regions of cracking affect the magnitude of actions (temperature loads uneven seabed effects

such as in response to accidents or abnormal level seismic eventsmdash For slender members in compression where deflection effects are significant (imperfection bending or

buckling)

402 A non-linear analysis is able to simulate effects of geometrical or material nonlinearities in the structureor a structural component These effects increase as the loading increases and require an application of theloading in steps with solution of the equations a multiple of times The load must be applied in steps orincrements and at each loading step iterations for equilibrium must be carried out403 Non-linear solutions cannot be superimposed This implies that a non-linear analysis must be carried outfor every load case or load combination for which a solution is requested404 Non-linear analysis of the global structure or significant components may be based on a relatively simplesimulation model Where linear elastic elements or members are included in this simulation it shall bedemonstrated that these components remain linear throughout the applied actions Appropriate stress-strain orload deflection characteristics shall be assigned to other components Deflection effects shall be incorporatedif significant405 Non-linear analysis of components to determine their ultimate strength shall normally be performed onrelatively simple simulations of the structure or on small components such as connections Complex non-linearanalysis of such D-regions using finite element methods should not be used without prior calibration of themethod against experimental results of relevance Material properties used in non-linear analysis should bereduced by appropriate material partial safety factors in accordance with Section 5 Where components of thestructure rely upon nonlinear or ductile behaviour to resist extreme actions such components shall be detailedto permit such behaviour

406 Only linear elastic stress-strain curves for FRP reinforcement shall be included in the analyses This willlimit redistribution of forces in the concrete structure

Offshore Standard DNV-OS-C502 September 2012 AppD ndash Page 175

APPENDIX D USE OF ALTERNATIVE DETAILED DESIGN STANDARD (GUIDELINES)

A General

A 100 Introduction101 The detailed design may be carried out in accordance with Section 6 the detailed requirements forconcrete design An alternative detailed reference standard may be found acceptable provided the standardsatisfy the provisions in this Appendix102 Other recognised codes or standards may be applied provided it is documented that they meet or exceedthe level of safety of this DNV Offshore Standard103 The detailed design shall be carried out in accordance with a recognized reference standard covering allaspects relevant for the structural design of Offshore Concrete Structures This Appendix identifies areas of thedetailed design standard that shall be checked for adequate coverage For complex structures where highergrades of concrete are used and where the loading conditions are severe most or all of the items in A200 shallbe covered

Guidance noteThe detailed design reference standard to be used should be agreed at an early stage in a project as the choice ofstandard might strongly influence the platform geometry and dimensions

A 200 Conditions201 The reference standard shall give the design parameters required for the type of concrete eg normalweight or lightweight concrete and strength class used For high strength concretes and lightweight concretethe effect of reduced ductility shall be considered This in particular applies to the stressstrain diagram incompression and the design parameter used for the tensile strength in calculation of bond strength andtransverse shear resistance202 Shell types of members are typical in offshore structures the reference standard shall cover designprinciples applicable to members such as domes and cylinders where relevant The design methods shall begeneral in nature considering equilibrium and compatibility of all the six force components giving stresses inthe plane of the member and all limit states203 The reference standard shall give the principles required for the design for transverse shear where thegeneral condition of combinations of simultaneously acting in plane forces eg tension and compression andtransverse forces shall be covered The interaction dependant of directionality of same forces in members likeshells plates and slabs shall be included Due consideration shall be given to the handling of action effectscaused by imposed deformations204 The reference standard shall give principles required for the design for fatigue for all failure modes Thisincludes eg concrete in compressioncompression or compressiontension transverse shear considering bothshear tension and shear compression reinforcement considering both main bars and stirrups including bondfailure and prestressing reinforcement Material standards might give certain fatigue-related requirementsthese are normally not adequate for offshore applications The fatigue properties will vary significantly also formaterials that pass such general requirements for fatigue For the design S-N curves representing the 25fractile should be prepared for rebars and in particular for items that have stress concentrations such ascouplers end anchors and T-heads205 The reference standard should give the principles and criteria applicable to ensure a durable design inmarine environment Important in this context is

mdash the selection of adequate materials which shall be in accordance with Section 4mdash adequate concrete cover to reinforcement see Sec6 Q200mdash limitation of crack-widths under SLS conditions see Sec6 O300

206 The reference standard shall give the principles for tightness control Tightness shall be considered underSLS conditions This shall apply to ingress of water in structures in floating conditions and in installedcondition when having internal under-pressure as well as leakage in particular of stored hydrocarbons fromstructures having internal overpressure Leakage shall also be considered in the design of the members that areaffected when maintaining a pressure gradient is vital like in suction foundations and when using air cushions207 Adequate tightness or leakage control shall be required in ULS and ALS for those conditions where aleakage might cause collapse or loss of the structure due to flooding or where a pressure condition required tomaintain equilibrium might be lost208 The reference standard shall give the design principles required for design of prestressed concreteincluding principles for partial prestressing when appropriate

209 The effect of the presence of empty ducts during phases of the construction period shall be consideredFor the final condition the effect of the presence of ducts on the capacity of cross-sections shall be consideredin particular if the strength and stiffness of the grout is less than that of the concrete This also applies if theducts are not of steel but of flexible materials210 The reference standard shall give the principles required to design all relevant types of members forsecond-order effects including buckling also in the hoop direction of shell types of members211 The reference standard shall give the principles required in order to assess the effects of water pressurepenetrating into cracks and pores of the concrete affecting both the load effects and the resistance The methodsto be used are dependent of how water pressure is applied in the initial calculation of action effects212 The reference standard shall give the principles for the local design in discontinuity regions where strutand tie models might be used to demonstrate the mechanisms for proper force transfer213 The reference standard shall give the principles required to permit design for imposed deformationsbased on strains rather than forces in all limit states Where brittle failure modes are involved such as shearfailure in members with no transverse reinforcement conservative design parameters shall be assumed in ordernot to underestimate the risk of the potential brittle failure modes214 The reference standard shall give guidance for how to assess the effect of gain in strength beyond 28 daysand also the effect of sustained loads or repeated loads at high stress levels in reduction of strength of concretewhen the gain in strength is intended for use in the design215 The reference standard shall give design principles required for demonstration of adequate fire resistanceof members subjected to fire including relevant material and strength parameters at elevated temperatures216 In zones with low to moderate seismic activity the action effects obtained from an analysis in which theplatform structure is modelled as linear elastic will normally be such that the structural design can be performedbased on conventional linear elastic strength analyses employing normal design and detailing rules for thereinforcement design217 In cases where the seismic action cause large amplitude cyclic deformations which can only be sustainedemploying plasticity considerations the reference standard shall give adequate requirements concerning designand detailing The regions of the structure that are assumed to go into plasticity experiencing excessivedeformations shall be carefully detailed to ensure appropriate ductility and confinement218 The material factors shall be such that a total safety level consistent with this standard is obtained Thisshall be documented

Offshore Standard DNV-OS-C502 September 2012 AppE ndash Page 177

APPENDIX E CRACK WIDTH CALCULATION (GUIDELINES)

A Steel reinforced structures

A 100 Introduction

101 The general basis for calculation of crack width in an offshore structure is provided in Sec6 O800

102 This Appendix provides recommendations for calculation of crack width for stabilized crack patternStabilized crack pattern is defined as a crack pattern developed in such a way that an increase in the load willonly lead to minor changes in the number spaces between cracks and direction of cracks

103 Normally a stabilized crack pattern is used in evaluation of crack width as the provision of minimumreinforcement in the structure is intended to ensure a well-spaced developed crack pattern

A 200 Stabilized crack pattern

201 Influence length lsk

For stabilized crack pattern the influence length lsk equals the characteristic distance between cracks srk

The characteristic distance between cracks for cracks normal to the reinforcement direction is predicted fromthe following formulae

where the summation Σ covers tensile reinforcement within the concrete area influencing the transfer oftensile stresses between concrete and tensile reinforcement between cracks Acef

202 In plates and slabs with single bars or bundles of bars of equal diameter and constant spacing betweenthe bars the distance between the cracks may be calculated from

where

sro = 20 mm (a constant length with presumed loss of bond)ftk τbk = the effective ration between tensile strength and bond strength and is taken as 075 for deformed

bars 115 for post-tension bars and 150 for plain bars Acef = b middot hcef the effective concrete area in the part of the concrete tension zone which is presumed to

participate in carrying tensile stresses which is transferred from the reinforcement to the concreteby bond

b = the width of the effective concrete section considered (mm)hcef = the height of the effective concrete area = 25 (h ndash d) where (h ndash d) is the distance from the

concrete surface on tension side to the centre of gravity of the reinforcement For a tension zonewith reinforcement of single tensile bars in one layer hcef = 25 (c + φ 2)

hcef shall be less than the height of the tensile zone (h ndash x) where x is the distance from the concrete edge onthe tensile side to the neutral axis and h is the total cross-sectional height

For double reinforce cross-sections with through going tensile stresses hcef is calculated for each side hcef shallin this case never be larger than h2

kc = a coefficient which accounts for the strain distribution within the cross-section

kc = (1 + εIIεI)2 where εIIεI is the ratio between minimum and maximum strain in the effectiveconcrete area calculated for cracked cross-section For a cross-section with through going tensilestresses kc =10

kb = 015 n + 085 a coefficient which accounts for reduced bond of bundled reinforcementc = the concrete cover for the reinforcement under investigationφ = the diameter of the reinforcement barsb = the distance between reinforcement bars or bundles of bars maximum value in the calculation 15φ

(for bundles of reinforcement n = number of bars in a bundle

+==

bkbtk

cefcromrk

kf

Aksss

τπφ7171

( )

sdotsdot

+==φπ

τn

shkkfsss bcefcbbktk

romrk 7171

nφ15

203 Characteristic distance between cracks srk shall not be larger than 25 (h - x) and not less than 25 cwhere c lt (h-x)

204 Should the reinforcement be distributed unevenly between different parts of the cross-section then thecharacteristic distance between the cracks srk shall be predicted individually for groups with similar intensityof reinforcement

205 For reinforcement with perpendicular reinforcement bars spaced at a distance s then the characteristicdistance between the cracks can be taken as n middot s where n is a whole number and when the predicted distancebetween the cracks is greater than n middot s and less than (n + 03) s

A 300 Distance between cracks with deviations between the principle strain directions and the direction of the reinforcement

301 When the principal strain deviate from the direction of the reinforcement then the distance between thecrack width in the direction of the main reinforcement may be predicted from

where

ν = the angle between the principle strain and the y-direction (x-direction) when the reinforcement ispresumed to be position in the xndashdirection (y-direction)

smx = the predicted distance between the cracks in the x-directionsmy = the predicted distance between the cracks in the y-direction

A 400 General Method

401 The mean tensile strain εsm may be calculated using the principles outlined in Sec6 H The mean strainmay be calculated based on the assumption that the concrete contribute between the cracks with an averagetensile stress βs ftk and a corresponding strain εcm = βs ftk Eck

where

βs is the ratio between the mean tensile stress and the tensile strength of the concrete in the influence area ofthe characteristic crack

βs = 06 for short duration one time loadings= 04 for long duration or repeated loads at actual load level

Eck = 9500 (fcck)03

A 500 Simplified Approach

501 The crack width may be calculated by the following simplified equation

where

σs2 = stress in the reinforcement in the crack for the actual cross-sectional forces

σsr2 = reinforcement stress at the crack location for those cross-sectional forces which give maximum tensilestress in the reinforcement at cracking of the concrete (max tensile stress in concrete equal to tensilestrength) The calculation of reinforcement stress is based on cracked concrete

srk = See A200 above

σsr2 is calculated based on the same ratio between the cross-sectional forces (the same location of the neutralaxis) as used in the calculation of σs2 and shall not be larger than σs2

For structures exposed to water pressure the reinforcement stress σs2 shall include the effect of full waterpressure pw on the crack surface Additional simplification may be made by presuming βs = 0 thus neglectingthe shrinkage strain

B FRP reinforced structures

These guidelines predict the crack width in structural elements which are reinforced by FRP surfacereinforcement

For structures reinforced by a mixture of steel reinforcement and FRP reinforcement the provisions of A applies

mymx

m

ss

s νν cossin1

+=

minus

minus= cssk

s

srsrkk E

sw εσσσβ 2

2

21

For prestressed reinforcement the prestressing force should be considered as an applied normal force andmoment If steel tendons are used then the crack width criteria for sensitive reinforcement in Sec6 O303applies

FRP reinforced concrete members only

The characteristic crack width for beams and slabs is taken to be equal to

wk = 12 wm

and for pre-stress beam using FRP reinforcement it is taken as

wk = 14 wm

where wm denotes the mean crack width calculated for the mean elongation ɛsm which is produced along theaverage distance Srm between cracks

wm = Srm εsm

If more accurate data are not available the parameters Srm and ɛsm of the previous equation can be assessed asfollows provided that the reinforcement is distributed in a sensibly uniform manner in the effective embedmentsection of the concrete

a) after cracking has stabilized the final average distance between cracks in the effective embedment section(see figure 1) is

wherec denotes the concrete cover for beam with side net of reinforcement and for deep beams the sidersquos covershould be useds denotes the spacing of the reinforcing bars S le 15 ϕ ϕ denotes the bar diameterk1 denotes coefficient which characterizes the bond properties of the bars

k1 = 04 for high bond barsk1 = 08 for plain bars

k2 denotes the coefficient representing the influence on the form of stress diagram

k2 = 0125 in bending k2 = 025 for pure tension ρr = AsAceff

As denotes the area of reinforcement contained in Aceff

Aceff denotes the effective concrete area (effective embedment zone) where the reinforcing bars caneffectively influence the crack widths

Aceff = b hceff

wherehceff = βceff (h-d) βceff is the coefficient for effective height for beams it can be calculated using figure 2 For slabs (wheret le 03 m) βceff = 25

Figure 1 Effective concrete area

rrm

scS

ρφκκ 21)

10(2 ++=

Figure 2 Coefficient of effective height

b) The mean elongation of the reinforcement situated in the effective embedment section taking account ofthe contribution of the concrete in tension can be taken as being equal to

whereσs denotes the stress in the reinforcement in the cracked section under combination of actions underconsiderationσsr stress in the reinforcement calculated on assumption of a cracked section where the maximum tensilestress in the concrete (un-cracked section) is taken equal to Ftkβ1 denotes coefficient which characterises the bond properties of the bars β1 = 1(25 k1)

β1 = 10 for high bond barsβ1 = 05 for plain bars

β2 coefficient representing the influence of the duration of application or repetition of loads

β2 = 10 at the first loading β2 = 05 for loads applied in a sustained manner or for a large number of load cycles

Coeffecient of effective height (βceff )

5 1125

20 75

40 25

100 05

48 05

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60 70 80 90 100

Concrete Cover in mm

Coef

ficie

nt o

f effi

ctiv

e he

ight

(βc

eff )

s

sr

s

ssm EE

σσσββσε 401

2

21 ge

minus=

Offshore Standard DNV-OS-C502 September 2012 AppF ndash Page 181

APPENDIX F REQUIREMENTS TO CONTENT IN MATERIAL CERTIFICATES FOR

FRP BARS

A General

A 100 Minimum requirements101 This standard opens for designing structural elements using FRP reinforcement bars of carbon glassaramid or basalt fibre reinforced composites 102 In order to use this standard in evaluation of the structural capacity of structures using FRP reinforcementand in order to achieve comparative safety levels as required for steel reinforced concrete members test resultsshall be included in a Material Certificate103 A Material Certificate shall be provided with each bar delivery The Material Certificate shall state as aminimum the information listed in Table A1

Table A1 Information to be stated on bar Material Certificates Reference to the relevant product specification

Batch number and production dates

Permissible temperature range

AF BAR Cross sectional area of bar

ρF Density of FRP bar (kgm3)

DB Nominal bar diameter

mtex Amount of fibres in the bar in tex (gkm) (alternative tow size in tex and number of tows)

mf Fibre fraction by weight

EF Characteristic value of the Youngrsquos modulus of FRP reinforcement bar at qualified temperatures

fF bend Characteristic strength of bent part of FRP bar

fF Characteristic value of short term tensile strength

fF TTR Characteristic tensile strength (force per area) in FRP bar until failure in TTR tests at reference durations

Characteristic strengths fF bend fF fF TTR documented for elevated temperature testing

Characteristic strengths fF fF TTR documented for alkali degradation testing

γF Material factor to account for variation in strength placement amp manufacturing control used to find γFI γFII γFIII for design see Sec6 C113

γFssa Material factor to be used for long term safe service life assessment

γFA Material factor to be used in accidental limit states

γFE Material factor on Youngrsquos modulus of FRP bars accounting for long term creep effects in the bars

ηF TTRI Conversion factor for loads of duration 50 years corresponding to load combination type I

ηF TTRII Conversion factor for loads of duration 1 year corresponding to load combination type II

ηF TTRIII Conversion factor for loads of duration 1 week corresponding to load combination type III

ηT Temperature conversion factors for qualified temperatures outside -20 to +20degC

ηb Conversion factor for bends for the bend radiuses covered

C Coefficient of characteristic safe service life formula (or parameters of other documented fatigue formulation)

k1 Bond Strength factor for FRP reinforcement relative to values in Sec6 Table K2 Sec6 K116

kdB Coefficient in deflection calculation in Sec6 O1204

Reference to test reports for pull-out bond strength testing at each qualified temperature

Reference to fatigue testing test reportsat qualified application temperatures

Reference to full scale elements test reports

Reference to applicable standards

Quality management system and Manufacturing Service Arrangement (or similar) Ref Nos

Reference to Material amp Supplier quality control documents Certificates

B Testing of Materials

B 100 Recommended testing

101 Laboratory testing of the FRP material and bar products shall be carried out as part of a completequalification programme to document its properties for use in design

102 Each of the parameters in Table A1 shall be documented though a pre-qualified test programme Thetesting required for each is given in Table B1

103 Recommended tests for FRP bar products are tabulated in Table B2

B 200 Requirements of testing

201 Each bar dimension of each bar type and grade shall be characterised prior to use The properties of eachbar configuration and size shall be referred to the cross section area for that bar size in the bar data sheet(product specification) provided by the manufacturer

Table B1 Critical Parameters and corresponding recommended testsEF E-modulus testing (instant elongation in response to tension) bar at qualified temperatures

fF bend Embedded tensile strength of bent bars

fF Embedded static tensile strength testing

fF TTR Embedded time to rupture tests at qualified temperatures

γFssa Embedded cyclic fatigue time to rupture tests at qualified temperatures

γFA Embedded static tensile strength testing

γFE Creep testing (elongation due to sustained tension)

αF Thermal Expansion Testing (elongation of bars due to temperature)

ηT Embedded static tensile strength testing outside -20 to +20degC

ηb Bend Testing of bars embedded in concrete

C Embedded cyclic fatigue time to rupture tests at qualified temperatures

k1 Pull-out bond strength

kdB Full Scale Beam Testing

Table B2 Recommended tests methods ndash FRP bars

ParameterTest method

CommentISO

10406-1CSA

806-02ACI

4403R-04

Tensile strength in air Sec6 AnnC B2 Embedment conversion factor needed

Embedded tensile strength NA NA NA No standard tests are available for bars embedded in concrete

Pull-out bond strength Sec7 AnnFAnnD B3

Tensile strength of bent bars NA AnnE B5

Alkali resistance Sec11 AnnO B6

Standard methods permit alkali exposure without loading Effect of sustained and cyclic stress on alkali degradation needs to be documented in addition Embedment conversion factor needed

Cyclic fatigue in air Sec10 AnnL B7

Standards allow test frequencies of 1 ndash 10 Hz The lower range is recommended Anchor failures should not be counted as bar failure Embedment conversion factor needed in addition for structural design

Embedded cyclic fatigue time to rupture NA NA NA No standard tests are available for bars embedded in

concrete

Time to rupture in air Sec12 AnnJ B8Anchor failures should not be counted as bar failure Embedment conversion factor needed in addition for structural design

Embedded time to rupture NA NA NA No standard tests are available for bars embedded in concrete

Long term relaxation in air Sec9 B9Long term creep AnnJ Coefficient of thermal expansion AnnM

202 The testing described in B100 is to be carried out for each bar diameter to be used in design After thefirst bar diameter has been successfully qualified subsequent bars diameters may require a less complete testingschedule for qualification this may be decided upon review of the bar specific test data203 Testing is normally conducted at one particular reference temperature typically room temperature(20 to 23degC) The properties of FRP bars may however be subject to change under different ambientoperational temperatures It is thought that the performance of the bars will not be detrimentally affected torequire additional testing if operation is restricted to temperatures down to -20degC However the performanceof the bars at elevated temperatures (above +20degC) if required for likely application shall be proven anddocumented by relevant testing204 Reinforcing FRP bars may be tested according to relevant international standards or guidelines such asISO 10406-1 CSA 806-02 ACI 4403R-04 However additional characterisation shall be performed tocharacterise critical parameters not covered by those standards and guidelines In particular the performanceof the FRP bars as embedded in concrete shall be documented by testing Any effects of mechanical stress onalkali degradation shall also be documented by relevant tests205 Bar tensile strength shall be characterized in terms of the rupture strength due to tension that increasesat a constant rate till rupture hereafter denoted ldquoshort term tensile strengthrdquo for test durations of 2 to 5 minutesIf tests of bars in air are used to obtain the tensile strength of the bars (eg according to ISO 10406-1 Sec6 orACI 4403R-04 SecB2) these tests must be complemented with tests of the bars embedded in concrete todetermine the conversion factor from strength in air to embedded strength206 Fatigue performance of the bars shall be documented by tests with cyclically varying tension loadingwhere the number of cycles to failure is recorded Tests shall be performed at mean stress levels and stress cyclemagnitudes representative of the intended use of the bar If tests of bars in air are used to obtain the fatigueperformance of the bars (eg according to ISO 10406-1 Sec6 or ACI 4403R-04 SecB2) these tests shall becomplemented with fatigue tests of the bars embedded in concrete to determine the conversion factor fromfatigue performance in air to embedded fatigue performance207 Sustained load performance of the bars shall be documented by tests with constant sustained tensionwhere the time to rupture (TTR) is recorded If tests of bars in air are used to obtain the TTR of the bars (egaccording to ISO 10406-1 Sec6 or ACI 4403R-04 SecB2) these tests shall be complemented with TTR testsof the bars embedded in concrete to determine the conversion factor from sustained load performance in air tosustained load performance as embedded in concrete208 The value of fF TTR the characteristic tensile strength (force per area) in the FRP bar until failure duringTTR testing shall be documented for durations of loading ranging from 1 hour to 1 year 209 The effect of exposure to the alkali environment within moist concrete on the static tensile strengthfatigue and sustained load performance shall be established by testing where the bars are exposed to a realisticenvironment This should be done at least for the smallest bar dimension of each bar configuration210 Adequate bonding of the bars to the concrete shall be documented by relevant tests The pull-out strengthmeasured according to standardised tests (eg ISO 10406-1 Sec7 or ACI 4403R-04 SecB3) is well suited tocompare bond strength of different bar configurations For documenting the actual bonding performance of aspecific bar in concrete such pull-out tests shall be complemented with representative tests of structuralelements showing adequate performance with regard to crack distribution and width debonding failuresspalling anchorage of the bars and overlap splicing of the bars211 The performance of the bars at bends eg in stirrups shall account for reduced tensile strength at thebend The value of this reduction factor shall be documented by tests As a minimum the strength of bendsshould be determined experimentally for the largest cross section and smallest bend radius of each barconfiguration in which case this bend strength can be applied to all bar dimension of that configuration If thestrength of bends is established for more than one bar dimension and bend radius interpolation can be used toobtain strength values for intermediate cases Extrapolation shall not be performed to more favourable strengthvalues than documented by testing

Offshore Standard DNV-OS-C502 September 2012 AppG ndash Page 184

APPENDIX G QAQC SYSTEM FOR MANUFACTURE OF FRP BARS (GUIDELINES)

A General

A 100 Minimum documentation

101 This appendix provides guidelines for QAQC systems for manufacturing of FRP bars

102 The method and documentation of verification of incoming raw materials by the bar manufacturer andthe bar manufacturerrsquos own acceptance criteria shall be specified in the quality system As a minimum a WorksrsquoCertificate issued by the raw material suppliers shall be verified against the bar manufacturerrsquos acceptancecriteria and filed If type approved materials are specified for the production this shall be verified Testingcarried out shall be described covering test equipment test methods test samples and reference to the teststandards used

103 The Worksrsquo Certificate from the fibre supplier should state all information considered relevant by the barmanufacturer not to be limited by the minimum information listed in Table A1

104 The Worksrsquo Certificate from the resin supplier should state all relevant information not to be limited bythe minimum information listed in Table A2

Table A1 Information to be stated by fibre supplier in Workrsquos CertificateType designation ie product name (grade) with list of tow weight (variants)Name and address of the manufacturerBatch number and production date(s)Manufacturers product specificationdata sheet including

mdash Fibre Type designation sizing (coating) and sizing contentmdash Fibre diameter with tolerancesmdash Chemical composition of the actual minerals with tolerancesmdash Type and application of coupling agents (if any)mdash Powder or emulsion boundedmdash Tow size (tex) with tolerancesmdash Moisture contentmdash Specified minimum fibre strength with reference to the test standard usedmdash Specified minimum fibre modulus with reference to the test standard usedmdash Specified maximum alkali degradation of bare fibre with reference to the test standard and conditions used (this

serves as a means to control uniformity of material quality and is not used in design)Fields of application and special limitations of the product The suitability for service in the alkali environment as embedded in concrete should be addressed and whether this warrants any particular requirements for bar productionReference to specification of fabrication processesReference to specification of quality control arrangementQuality system certificationDescription of packing of the productInformation regarding marking of the product Relevant service experience if availableType approvals of the product from relevant certifying agents

Table A2 Information to be stated by resin supplier in Workrsquos CertificateType designation ie product nameName and address of manufacturer Product description (type of base resin etc)Field of application and special limitations of the product (curing procedure laminating procedure shelf life compatibility non-compatibility with other materials etc) considering specifically the intended service in the alkali environment as embedded in concrete and measures needed to ensure bonding to concreteReference to product specification data sheet (mechanical properties health data sheets etc) stating at least Specified maximum alkali degradation of neat cured resin with reference the test standard used

mdash Specified minimum elongation at break with reference the test standard usedmdash Temperature of deflection or glass transition temperature for the cure cycle specified for the bar manufacturing with

reference the test standard usedTest results with reference the test standard used Reference to specification of production processes

105 Other incoming material shall have a marking that shall at least include the following information listedin Table A3

106 The conditions under which raw materials are stored shall be described As a minimum the allowablerange of temperature and relative humidity shall be specified as well as the method for controlling and loggingthese conditions Cleanliness of the storage area shall be addressed as well as precautions if original packagingon stored material is broken The control of shelf-life of products shall also be described

Guidance noteThe storage area shall be free from dust and other types of contamination that can have an adverse effect on the qualityof the finished product

107 The FRP bar manufacturer shall completely describe each step in the production process of the bars fromthe production of each raw material input used to the delivery of the bar product It shall also provide anoverview of the production in general For each step in the production process aspects of particular importanceshall be identified and how these aspects are taken care of by the techniques of manufacturing and qualitycontrol shall be described The production parameters used for this control shall be identified and their targetvalues and tolerances specified The quality system including quality procedures and manufacturinginstructions shall account for these aspects

108 A specification shall be made describing all relevant production parameters including details of how eachshall be recorded and logged

109 Special attention shall be given to the cleanliness of the fabrication area The fabrication area shall befree from dust and other types of contamination that can have an adverse effect on the quality of the finishedproduct

110 The equipment used for curing and procedure for verification of the cure cycle shall be described

111 The method and equipment used for cutting of the bars to length shall be described

112 The extent of the manufacturers quality control after production shall be documented

113 During bar production the characteristic values of strength and stiffness stated on the MaterialCertificate or data sheet shall be confirmed This shall be accomplished by means of tests of bars produced fordelivery The plan for the tests during production shall be specified by the bar manufacturer and included in theQA system in operation The extent of testing shall be sufficient to confirm compliance of the as produced barswith the product data sheet

The test plan shall be so designed as to provide data for the variability of bar strength from continuousproduction at the facility It shall be verified that these estimates do not fall short of the characteristic valuesused in design

A particular test plan for QC in combination with the QA measures as implemented in the quality systemapplies to one set of production parameters for one manufacturing machine at one site

In case a nonconforming result is obtained from these tests all bars produced since the previous conformingtest result shall be treated as non-conforming

114 Each FRP bar product shall be given a unique product name and a product specification uniquelyidentifying the bar product Each bar product may be provided in a range of bar sizes A cross sectional areashall be specified for each bar size A nominal area based on the specified cross sectional fibre content (mass)of the bar is recommended Alternatively the area can be based on size measurements on produced bars In thatcase special care must be taken to ensure that the cross sectional areas used in processing of bar test results andin stress calculations are the same The product specification for each bar product should include theinformation listed in Table A4

Reference to specification of quality control arrangement Quality system certificationInformation regarding marking of the product and packaging Type approvals of the product from relevant certifying agents

Table A3 Required marking of incoming materialManufacturerrsquos nameProduction plantProduct name (grade)Storage instruction (if applicable)Production date

Table A2 Information to be stated by resin supplier in Workrsquos Certificate (Continued)

115 The product or package shall be marked The marking shall be carried out in such a way that it is visiblelegible and indelible The marking shall at least include the following information

mdash Manufacturerrsquos namemdash Production plantmdash Product name (type and grade)mdash Storage instruction (as applicable)mdash Production datemdash Batch numbermdash Bar size (eg diameter)

116 Packaging spooling and other handling shall be according to procedures specified by the manufacturer

117 The procedure for handling and installation shall contain the necessary instructions and limitations set toprotect the integrity of the bars during construction and in the installed condition This should in particularconsider required measures to prevent damage from exposure to UV radiation solar heating local bendingcrushing and contamination of the bars that may compromise bonding to the concrete

A 200 Physical properties of bars

201 Cross sectional properties can be defined as follows The net fibre area in a FRP cross section is the sumof the cross section areas of all the fibres in the cross section It can be computed from the specified tex massvalue as follows

Table A4 Basic information to identify a FRP barDesignation of bar type (grade)Constituent materialsFibre type diameter and designationTow sizeResin type (eg epoxy polyester) Specific resin type (trade name full designation)Bar propertiesCross sectional area(s)Net fibre area in a FRP reinforcement bar (Af)Fibre mass per unit length (tex)Net fibre area of tow (aftow)Bar diameter(s)Cross sectional irregularities (eg waviness ribs) with tolerancesReference to technical datasheet with design data for mechanical propertiesProcess parametersUnique reference to processing specification for the specific bar type and gradeProcessing temperatureSurface finish (eg sand cover)Fibre volume fractionMax content of voids porosities and dry areasPermissible environmental conditions for use of the barsTemperature rangeHumidity conditionsChemical environment (incl pH)For each parameterMeasured valuesGuaranteed minimum valuesEstimated standard deviation based on testsNumber of specimens testedOther Reference to applicable Rules and Standards the product complies with

[ ] [ ][ ]3

f

2 kgm

gkmmm

ρtex

towf

ma =

202 where ρf is the density of the fibre ndash a convenient consistent set of units is specified in square brackets ndashThe variability of this area is usually small The volume fraction of fibres is obtained from the average massfraction by

203 where mf is the average mass fraction of fibres from production records and mm is the average massfraction of matrix resin (mm = 1 ndash mf) The nominal bar cross sectional area is given by the volume fraction offibres and the net fibre area

204 where the fibre area and N is the number of tows in the bar All bar stresses are defined interms of the nominal bar section area

Although the cross section may be intentionally irregular one may for convenience define the nominal bardiameter assuming a circular cross section

This nominal diameter can be used to calculate the barrsquos surface area for design calculations

m

f

f mm

m

v

ρρ

ρ

+=

f

fB v

AA =

towff aNA sdot=

B

BB A

Ff =

πB

B

AD 2=

Offshore Standard DNV-OS-C502 September 2012 AppH ndash Page 188

APPENDIX H REQUIREMENTS TO CONTENT IN MATERIAL CERTIFICATE FOR

STRUCTURAL GROUT

A General

A 100 Minimum requirements101 This standard opens for designing structural details using grout or grout material reinforced by fibrereinforcements The fibre may be made from either steel of FRP 102 Grout material shall be delivered to site ready for application only water may be added at theconstruction site prior to use The product is generally dependent on the constituent materials entering the mix 103 In order to use this standard in evaluation of the structural capacity of the grout and in order to achievecomparative safety levels as required for reinforced concrete members test results shall be included in aMaterial Certificate 104 The Material Certificate shall contain documentation specific to the type and means of application of thegrout material see C105 For structural grout a Material Certificate shall as a minimum contain the following parameters andinformation

Note where a parameter is only relevant to certain applications or materials (neat cement grout or pre-packedblended grout) it has been marked ldquoas applicablerdquo

Table A1 Minimum contents of material certificate for structural grout Details of producer owner of certificateMaximum aggregate size (as applicable)Weight of dry grout (per packaged quantity) (as applicable)Weight of fresh water (per packaged quantity of grout) (as applicable)WC Ratio (as applicable)Range of qualified application temperaturesWorkability over an applicable duration ndash Flow test resultDensity ndash fresh and hardenedAir content ndash fresh groutStability (separation and bleeding)Setting time (initial and final)Mean compressive strength (150 times 300 mm cylinders) at 3 days at ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 7 days at ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 28 days ttest min and 20degCCharacteristic compression strength (150 times 300 mm cylinders) at 28 days ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 90 days ttest min and 20degCMean compressive strength (of 75 mm cubes) at 28 days 20degCCharacteristic compression strength of 75 mm cubes at 28 days 20degCRatio between standard cylinder strength and control specimens to be used at siteTensile strength (flexural strength test) at 28 day at ttest min and 20degCCreep properties Autogenous shrinkage total shrinkage expansion properties (as applicable)Young modulus at 28 daysPoissonrsquos ratio at 28 daysFatigue parameter ndash C5Pumpability (with reference to approved mock-up test and test temperature)Compression strength development at elevated temperature (as applicable)Doc No of approved grouting procedures Ref to approved production sites

106 For fibre reinforced structural grout the Material Certificate shall as a minimum contain the followingparameters and information

B 100 Recommended testing101 Laboratory testing of the fresh and hardened grout material shall be carried out to document its propertiesfor use in design 102 The testing specified in this sub-section should be carried out by an independent laboratory holding ISO17025 or similar accreditation as well as ISO 9001 certification

Table A2 Minimum contents of material certificate for fibre reinforced structural groutProducer Maximum aggregate size (as applicable)Weight of dry grout (per packaged quantity) (as applicable)Weight of fresh water (per packaged quantity of grout) (as applicable)WC Ratio (as applicable)Works Certificate for fibre amp resin raw materials Volumetric content of fibres Fibre type Fibre length Volumetric content of fibres Wt of fibres m3 grout Range of qualified application temperaturesWorkability over an applicable duration ndash Flow test resultDensity ndash fresh and hardenedAir content ndash fresh groutStability (separation and bleeding)Setting time (initial and final)Mean compressive strength (150 times 300 mm cylinders) at 3 days at ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 7 days at ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 28 days ttest min and 20degCCharacteristic compression strength (150 times 300 mm cylinders) at 28 days ttest min and 20degCMean compressive strength (150 times 300 mm cylinders) at 90 days ttest min and 20degCMean compressive strength of 75 mm cubes at 28 days 20degCCharacteristic compression strength of 75 mm cubes at 28 days 20degCRatio between standard cylinder strength and control specimens to be used at siteTensile strength (flexural strength test) at 28 day at ttest min and 20degCLong term load effects relating to sustained load fracture in FRP fibre reinforced materialCreep properties Autogenous shrinkage total shrinkage expansion properties (as applicable)Young modulus at 28 daysPoissonrsquos ratio at 28 daysFatigue parameter ndash C5Pumpability (with reference to approved mock-up test and test temperature)Compression strength development at elevated temperature (as applicable)Doc No of approved proceduresRef to approved production sites

103 The following tests methods are recommended to document the fresh grout parameters of high strengthpre-packed blended grout

104 The following test methods are recommended to document the hardened grout material parameters ofhigh strength pre-packed blended grout

Table B1 Recommended test methods - Fresh grout

Test Id Type of Test Test Method Testing time (age) Suggested No of tests

Specified testing curing temp

ttest min 20degC

FG1 Flow test ASTM C2301)As soon as practicable after mixing and then at 30 60 90 and 120 minutes2)

1 no test specimen from each batch at each specified testing temperature

X X

FG2 Density EN 12350-6 As soon as practicable after mixing

X

FG3 Bleeding Segregation ASTM C940

As soon as practicable after mixing and periodically thereafter

X X

FG4 Air content EN 12350-7 As soon as practicable after mixing

X X

FG5 Setting time (initial amp final)

ASTM C191 or EN 196-33)

At regular time intervals after mixing until final set has been observed to produce a satisfactory penetration curve

X X

1) No shock or agitation shall be applied to the flow table

2) The material shall not be vibrated or excessively agitated between mixing and the test age

3) 1000g load shall be used above the needle rather than the standard 300g load specified in EN 196-3

Table B2 Recommended test methods - Hardened grout

ttest min 20degC

HG1 Density EN 12390-7 28 days 3 no specimens from each batch X

HG2

Compressive strength - 150 times 300 mm Cylinders

EN 12390-3 3 7 28 90 days

4 no cylinders from each batch at 3 7 and 90 days at each specified testing temperature4 no cylinders from each batch at 28 days at ttest minSufficient no of cylinders to compute characteristic strength value at 28 days at 20degC

X X

HG3Compressive strength 75 mm cubes

EN 12390-3 28 daysSufficient no of cube specimens to compute characteristic strength value

X

HG4 Flexural strength ASTM C348 or EN 196-1 28 days

4 no prisms from each batch at each specified testing temperature

X X

HG5 Creep ASTM C5121) 2 7 28 90 days and 1 year 2 no specimens from each batch X

B 200 Requirements of testing201 To document the material properties of the grout a minimum of three production batches shall berepresented in the samples for each of the tests specified in Table B1 and Table B2 to capture any potentialvariance in the manufacturing process

Guidance noteFor the purpose of documenting the characteristic compressive strength of the material it is recommended that aminimum of 20 test specimens taken from as many distinct production batches as practical are included in thesample

202 Testing described in Table B1 and Table B2 shall be carried out at a reference room temperature of 20degCand for grout intended for low temperature service at the minimum test temperature ttest min203 For grout intended for use in regions or environments where the curing or application temperature tappmax is expected to be greater than 30degC additional testing shall be conducted similar in scope to that requiredfor the minimum test temperature Additionally an elevated temperature pumpability testing shall beconducted204 Constituent materials mixing and testing equipment as well as the testing environment shall be pre-conditioned at the testing temperature for at least 24 hours prior to mixing This is highly important for testingthe grout at cold andor elevated temperatures Metallic testing equipment and moulds dissipate the heat out ofthe grout material when testing is conducted at low temperature ttest min205 Curing of specimens shall be conducted in accordance with EN 12390-2 Suitable calibrated moulds inaccordance with EN 12390-1 shall be used206 Test cubes and prisms for testing hardened grout should in the absence of specific requirements in theapplicable referenced standards be initially cured in moulds covered with non-absorptive and nonreactiveplates or sheets of tough durable impervious plastic at the specified test temperature The initial curingtemperature shall be recorded207 The time elapsed between grout mixing and the commencement of grout testing shall be recorded Thetests shall commence at a specified grout age The age shall be recorded within the following time accuracy

mdash Specified grout age within 24 hours after mixing plusmn 15 minmdash Specified grout age within 48 hours after mixing plusmn 30 minmdash Specified grout age within 72 hours after mixing plusmn 45 minmdash Specified grout age within 7 days after mixing plusmn 2 hrsmdash Specified grout age within 28 days after mixing plusmn 8 hrsmdash Specified grout age within 90 days after mixing plusmn 1 day

208 Temperature logging during low temperature qualification of materials and environment shall be carried

HG62)

Shrinkage expansion

ASTM C1573) (ASTM C490)

24 hours 28 days 8 16 weeks (32 and 64 weeks optional)

2 no specimens from each batch X

Autogenous shrinkage

No standard test method is available4)

X

HG7

Static Youngrsquos Modulus amp Poissonrsquos ratio ndash 150 times 300 mm cylinders

ASTM C469 28 days 3 no cylinders from each batch X

1) ASTM C512 specifies that the material to be tested first needs to be cured for 28 days before the samples are exposed to the creep loads Once the samples are under load the effect of creep is tested after 2 7 28 and 90 days and 1 year Since in practice the material is sometimes loaded before 28 days (ie pre-stressing of bolts at a specified minimum compressive strength) the test method may after due consideration be adjusted to capture this by loading the material before the specified 28 day curing age This should be clearly stated in the test report

2) Depending on the likely application of the material the most applicable test in this category should be chosen

3) Storage method of specimens between comparator readings shall reflect the likely application conditions

4) The test method shall be agreed with the Society prior to commencement of programme The test method shall isolate the autogenous shrinkage Therefore the method of storing the material during testing shall ensure that drying shrinkage does not occur and no expansive effects of storing the material submerged in water influence the result

Table B2 Recommended test methods - Hardened grout (Continued)

ttest min 20degC

out to ensure the required temperature is maintained throughout the casting curing and testing of thespecimens For strength testing the time between the specimens leaving the coolingheating chamber andtesting shall be limited to maximum 30 minutes

209 Fatigue testing has not been included in the above specified testing although it is strongly recommendedthat these tests are carried out Fatigue testing is required to determine C5 the fatigue strength factor see Sec6M200 However provision is made in Sec6 M201 for the use of C5 = 08 in the absence of witnessed testingThis figure is thought to be conservative

Guidance noteIf the material is likely to be exposed to ponding water or if it is to be applied subsea then the treatment of thespecimens during fatigue testing should reflect the realistic environmental conditions The test frequencies shouldreflect those expected during normal operation of the structure which the material will likely be applied in

210 If the grout material is to be considered to be frost (freeze thaw) resistant the requirements of a suitabletesting norm shall be satisfied Testing may be conducted in accordance with EN13687-1 which tests adhesionafter cyclical freeze thaw exposure or the Borarings method which assesses salt scaling of the material Additionalmicroscopic analysis of the hardened material in accordance with ASTM C457 should be used to verify thepore distribution

211 If early age compressive strength development data ie less than three days is required additionalcompressive tests of cylinders shall be carried out

212 If it is required to document the complete stress strain curve of the material including the descendingportion for instance when non-linear material behaviour is required for analysis a testing machine capable ofoperating under displacement control should be used

Guidance noteThe test conducted using displacement control should continue until a strain of 6permil is recorded Strains may bemeasured using optical mechanical or electrical extensometers or stereo-photo equipment

C Supporting Documentation

C 100 Minimum requirements

101 Test results and supporting documentation shall be summarised and evaluated in a consolidated testreport The fulfilment of the requirements specified in B200 shall be documented for the test programmeundertaken

102 Material and supplier quality certificates for aggregates cement mineral and chemical admixtures shallbe provided in accordance with Section 4

103 Details of a valid manufacturing plant quality management system in accordance with ISO 9001 andpreferably ISO 9004 shall be referenced on the Material Certificate

104 Details of a valid manufacturing plant survey scheme Manufacturing Survey Arrangement (MSA) orsimilar issued by DNV shall be referenced on the Material Certificate

105 The production method of application as well as the quality control of the mixing curing and placementprocess offshore can have a significant impact on the final as-built performance of the material The followingdocumentation shall therefore be approved and referenced in the Material Certificate

mdash Grouting procedures for standardised grouting operations offshore for each of the applications to bequalified These shall include contingency procedures

mdash Procedure for large scale mock-up test The mock-up test shall directly correspond to a grouting procedurefor a specific application The test-setup shall reflect the actual conditions and equipment to be used at thesite including the grout mixer and pump pumping height and hose with a representative nominal borediameter amp length to assess pumpability of the material The mock-up test shall demonstrate that thematerial maintains pumpability over the likely duration of the operation including possible pauses due toblockages or equipment failures The most challenging placement configuration expected offshore shall bereflected in the test plan including contingency procedures Appropriate material testing shall be conductedduring the test and complete filling of the intended volume shall be demonstrated after hardening Theprecise requirements with regard to the mock-up test depends on the grouting operation (and procedure)under consideration

mdash Procedures for all QC testing during offshore operations Hardened grout sampling as well as details of alltests to be carried out on constituent materials water and fresh grout shall be documented with regard tosuitable standards

mdash Procedures for casting curing transport of the offshore QC specimens The curing conditions should be

maintained during transport to as great a degree as is practical Transport between controlled curingenvironments (ie from curing tank on board the installation vessel to the curing tank in the testingfacility) should be limited to a maximum of 72 hours

mdash Details of the qualification program used to appoint third party grouting contractors (if applicable)

Offshore Standard DNV-OS-C502 September 2012 AppI ndash Page 194

APPENDIX I QAQC SYSTEM FOR MANUFACTURE OF STRUCTURAL GROUT OR

EQUIVALENT MATERIAL (GUIDELINES)

A General

A 100 Minimum requirements

101 This appendix provides guidelines for QAQC systems for manufacturing and batching structural groutproducts

102 Documentation of the verification of the incoming raw materialsrsquo properties by the grout manufacturerand the manufacturerrsquos own acceptance criteria shall be specified in the quality system As a minimum TestReports or Worksrsquo Certificates where applicable issued by the raw material suppliers shall be verified againstthe grout manufacturerrsquos acceptance criteria and filed Testing carried out shall be described covering testequipment test methods test samples and reference to the test standards used

Guidance noteThe storage area shall be free from contamination that can have an adverse effect on the quality of the finishedproduct

104 The grout manufacturer shall completely describe each step in the production process of the grout fromthe sourcing of each raw materials used to the delivery of the final product It shall also provide an overviewof the production in general For each step in the production process aspects of particular importance shall beidentified and how these aspects are taken care of by the techniques of manufacturing quality control shall bedescribed The production parameters used for this control shall be identified and their target values andtolerances specified The quality system including quality procedures and manufacturing instructions shallaccount for these aspects

106 The method and equipment used for proportioning and batching the raw materials shall be described

107 During grout production the values for fresh and hardened grout stated on the Material Certificate ordata sheet shall be confirmed This shall be accomplished by means of testing of material produced for deliveryThe plan for the tests during production shall be specified by the grout manufacturer and included in the QAsystem in operation The extent of testing shall be sufficient to confirm compliance

108 The test plan shall be designed to capture sufficient data including the variability of material qualityfrom continuous production at the facility It shall be continuously verified that the test results do not fall shortof the characteristic values used in design

109 A particular test plan for QC in combination with the QA measures as implemented in the qualitysystem applies to one set of production parameters for one proportioning and batching line at one site

110 The QA system shall specify how to handle non-conformities

111 Each delivered package shall be marked The marking shall be carried out in such a way that it is visiblelegible and indelible The marking shall at least include the following information

mdash Manufacturerrsquos name mdash Production plant mdash Product name (type and grade) mdash Storage instruction (as applicable) mdash Production date mdash Batch numbermdash Expiry date

112 The procedure for transport handling storage and installation shall contain the necessary instructionsand limitations set to protect the integrity of the grout material prior to and during construction It shall beaccording to procedures specified by the manufacturer

Section 1
- Introduction
- - A General
  - B References
  - C Definitions
  - D Abbreviations and Symbols

Page 2: DNV-OS-C502: Offshore Concrete StructuresDET NORSKE VERITAS AS Offshore Standard DNV-OS-C502, September 2012 Changes – Page 3 CHANGES General This document supersedes DNV-OS-C502,

FOREWORD

DNV is a global provider of knowledge for managing risk Today safe and responsible business conduct is both a licenseto operate and a competitive advantage Our core competence is to identify assess and advise on risk management Fromour leading position in certification classification verification and training we develop and apply standards and bestpractices This helps our customers safely and responsibly improve their business performance DNV is an independentorganisation with dedicated risk professionals in more than 100 countries with the purpose of safeguarding life propertyand the environment

DNV service documents consist of among others the following types of documentsmdash Service Specifications Procedural requirementsmdash Standards Technical requirementsmdash Recommended Practices Guidance

The Standards and Recommended Practices are offered within the following areasA) Qualification Quality and Safety MethodologyB) Materials TechnologyC) StructuresD) SystemsE) Special FacilitiesF) Pipelines and RisersG) Asset OperationH) Marine OperationsJ) Cleaner EnergyO) Subsea SystemsU) Unconventional Oil amp Gas

copy Det Norske Veritas AS September 2012

Any comments may be sent by e-mail to rulesdnvcom

This service document has been prepared based on available knowledge technology andor information at the time of issuance of this document and is believed to reflect the best ofcontemporary technology The use of this document by others than DNV is at the users sole risk DNV does not accept any liability or responsibility for loss or damages resulting fromany use of this document

CHANGES

Main changes