Steel Compliance from the Consulting Engineer's Perspective

Steel Compliance –The Consulting Engineers’ Perspective

Mark SheldonTechnical Director

October 2015

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The Compliance of Steelwork in Buildings from the Design Engineer’s viewpoint

What does a consulting engineer do

What doesn’t a consulting engineer do

3 Case Studies

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Offices: 87Countries: 28Employees: 7,000+

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Mark Sheldon – Technical Director, Structural Engineer

• Melbourne Park - Project Director for Margaret Court Arena • Project Director for Simonds Stadium (35,000 seats) – stages 1,2,3 & 4• Cebu Seaside Arena (Concept design for 10,000 seat arena in the

Philippines)• Melbourne Park – Technical Advisor role for National Tennis Centre• Structural Design Leader for Perth Arena (14,000 seats)• MCG Redevelopment (101,000 seats) Design Team Leader• Etihad Stadium (54,000 seats) Structural Design Team Leader• Roof Structure Design Team Leader for 10,000 seat Hisense Arena (incl

retractable roof)• Design Team Leader for concept of 34,000 seat TEDA Soccer Stadium,

Tianjin• Eden Park redevelopment (NZ) concepts and peer review• Team Leader for Delhi 2010 Commonwealth Games Siri Fort and Yamuna

Sports Complexes• MSAC Design Team Leader (Approx 300m x 80m sports indoor complex)• Peer Reviewer for Wembley National Stadium, UK• Designer for 44,000 seat Great Southern Stand, MCG• Specialist input on dynamics - Kuala Lumpur Convention Centre

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Analysis• Spacegass

What Does a Structural Engineer do ?

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Analysis• Spacegass• ETABS


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Analysis• Spacegass• ETABS• Rhino/Grasshopper


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Analysis• Spacegass• ETABS• Rhino/Grasshopper• Strand 7


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Analysis• Spacegass• ETABS• Rhino/G’hopper• Strand 7• Dynamo• RAPT• RAM Concept• Robot• GSA• etc


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Design and Detailing• Determine stresses in members• Select reo size or steel section

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AS4100 states that members and connections shall be proportioned so that:

∗

Where:S* is the design action effectØ is the capacity factorRu is the nominal section or member capacity

Limit state design philosophy


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Capacity factor () accounts for: Variations in material properties

Section and member dimensional tolerances

Fabrication and construction tolerances

Structural modelling inaccuracies

Ductility and reliability requirements

Load factors account for variability of load effects


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Pro

babi

lity

Pro

babi

lity

Pro

babi

lity

Design load effect = Nominal (characteristic) load effect x load factor

Nominal load effect Design load effect

Load effect

Capacity

Design capacity = Nominal (characteristic) capacity x capacity factor

Design capacity Nominal (characteristic) capacity

Probability of failure (shaded area) ~ 0.001

95th

Per

cent

ile

5th

Per

cent

ile


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Analysis• Spacegass• ETABS• Rhino/Grasshopper• Strand 7• Dynamo• RAPT• RAM Concept• Robot• GSA• etc• Revit


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2D documentation and detailing


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What Doesn’t a Structural Engineer do ?

Metallurgy

Chemistry

Forensics

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Procurement of Construction Products

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Procurement of Construction Products

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AS4100 ≤ 0.9

ErectionAS 4100

WeldingAS 1554

FabricationAS 4100

TestingAS 1391AS 1554AS 3678

Material supplyAS 1163 – Hollow SectionsAS 3678 – Plate AS 3679 – Open Sections

Australian Standards for steel design have been calibrated for Australian manufactured steels using a suite of Australian Standards. The designer assumes that the material being used on site meets these standards.


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The fine print: -

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The fine print: -

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The fine print: -

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The fine print: -

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The fine print: -

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The fine print: -

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The fine print: -

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The fine print: -

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Project details Australian steel specified

The problem Large hollow sections sourced from offshore Mill certificates provided in Chinese, but incomplete Chemical limit exceeded (apparently)

The outcome NATA certified testing performed in Australia Metallurgist consulted Chemical composition compliant (typo on sheets) Mechanical properties compliant

Steelwork accepted

Project A – Large Building Structure

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Project details Australian steel specified

The problem Non-compliant steel plate identified after site erection completed Plate sourced from overseas had yield strength less than specified Lack of traceability – could not establish which connections were affected

The outcome NATA certified testing performed in Australia Actual yield strength determined Weldability was deemed to be acceptable Risk based assessment – connections involving affected plate were not utilised 100% Plate accepted (slight increase risk of failure)

Project B – Large Building Structure

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Project details ~$2 billion port expansion project 20,000t marine steelwork / 10,000t structural steelwork Steel procured and fabricated in China

The problem Potential steel non-compliance Preliminary design completed to Australian Standards

The outcome Gap analysis between Australian and Chinese standards Compliance testing performed in Australia Design capacity adjustment

Project C – Port expansion

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Pros Potential cost savings ~$50m:

o Local fabrication ~ $5,000-$7,000/to Chinese fabrication ~ $2,000/to Fabrication only (excludes transport)

Potential schedule gains due to increased production rates


Cons Procurement issues: currency

variation, greater transport and logistic considerations and costs

Quality concerns and subsequent increased QA requirements

Increased schedule risk due to additional QA and/or rejected material

Increased technical/ design considerations

Increased steel tonnage due to member substitution after preliminary design (~8% total)

Pros and cons of using foreign steel

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Chemical composition

Mechanical properties

Dimensional tolerances

Manufacturing process

Material Supply

AS/NZS 1163 Structural steel hollow sectionsAS/NZS 1594 Hot‐rolled steel flat productsAS/NZS 3678 Structural steel – hot rolled plates…AS/NZS 3679 Structural Steel:

Part 1 – Hot‐rolled bars and sectionsPart 2 ‐ Welded sections

Australian Standards

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Following the gap analysis, supply tolerances remained non-compliant (including angle leg thickness, depth of section).

Options considered: Relax tolerances to Chinese limits and reduce capacity factor; or Reject all steel that does not comply

Reduction in capacity factors chosen as preferred method to mitigate procurement issues and schedule delays, and maintain similar probability of failure.


Dealing with non-compliance

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Capacities found for:

− Smallest geometry permissible by Australian Standards

− Smallest geometry permissible by Chinese Standards

% decrease in capacity calculated

Used as % decrease in Capacity Factor

Assessment undertaken for various sections and lengths


Reduction of capacity factors

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Steel section Capacity factor ()RHS / SHS 0.85

TFC 0.88EA / UA 0.80

CHS 0.81All other sections 0.90

New capacity reduction factors

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Project C – Port expansionP

roba

bilit

y

Design load effect

Load effect and capacity

Design capacity (Australian steel)

Probability of failure (Australian steel)

Probability of failure (Chinese steel)

Design capacity (Chinese steel)

Probability of load effect and capacity

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What Does this all mean ?Non-compliant steelwork can cause real problems such as: Material rejection and rework Project delays Redesign Increased risk of structural failure Insurance claims and litigation

Design documents state that materials must comply with Australian Standards, and the onus is on the Supplier/Contractor to satisfy this requirement.

The design engineer won’t spend hours checking the validity and traceability of the certificates. Structural engineers are not metallurgists.

Third-party certification by a reputable organisation is a wise investment

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Steel Compliance from the Consulting Engineer's Perspective

Engineering