Disaster management and seismic retrofitting

transcript

Disaster Management and Seismic Retrofitting

Dr K M Soni

Chief Engineer, CPWD, Mumbai

Major Disasters Worldwide

4th July 2017 Disaster management 2

Sl. No.

Name of Event Year Country and Region

Fatalities in the known history

1 Earthquake 1556 China, Shaanxi 830000

2 Earthquake 1731 China 100000

3 Cyclone 1737 India, Calcutta 300000

4 Yellow River flood 1887 China 9,00,000-20,00,000

5 Messina Earthquake 1908 Italy 123000

6 Earthquake 1920 China, Gansu 235000

7 Great Kanto Earthquake 1923 Japan 142000

8 Great Chinese Famine 1958-1961 China

1958-1961 China 150,00,000-430,00,000

9 Bhola Cyclone 1970 West Bengal, India & B/desh

5,00,000

10 Tangshan Earthquake 1976 China 2,42,419

HAITI’S E/Q, 12.1.2010; DEATHS-3,16,000; MAGNITUDE:7

34th July 2017 Disaster management

TANGSHAN, CHINA, 27.7.1976; DEATHS-242,769; MAG. 7.5

SUMATRA E/Q, 26.12.2004DEATHS;2,27,898MAG. 9.1

Haiyuan, chinae/q 16.12.1920Deaths; 2,00,000Mag. 7.8

Kanto, e/q, Japan; 1.9.1923Deaths-1,42,800Magnitude: 7.9

Pakistan e/q, 18.10.2005Deaths; 86000Mag-7.6

Iran e/q, 20.6.1990Deaths-50,000Mag. 7.4

Gujarat e/q, 26.1.2001Deaths-20,085, Mag. 7.6

Latur, india e/q 29.3.1993Deaths – 9748Mag. 6.2

NEPAL EARTHQUAKE

2015, Magnitude: 7.9, deaths over 5000

AFGHANISTAN EARTHQUAKE

26th October, 2015

Disasters in India

• Natural disasters– Earthquakes

– Floods

– Cyclones

– Tsunamis

– Droughts

– Landslides

• Man made disasters– Road/Rail accidents

– Chemical disasters

4th July 2017 15Disaster management

Major Disasters in India

S. No. Name of Event Year State & Area Fatalities

1. Floods October 2014 Jammu & Kashmir

2.Cyclone Hud

September

Andhra Pradesh &

Odisha

3. Odisha Floods October 2013 Odisha 21

4. Andhra Floods October 2013 Andhra Pradesh 53

5.Cyclone Phailin October 2013 Odisha and Andhra

Pradesh

6.Floods/Landslid

June 2013 Uttarakhand and

Himachal Pradesh

7.Cyclone

Mahasen

May 2013 Tamil Nadu 08

8. Cyclone Nilam October 2012 Tamil Nadu 65

Uttarakhand

Floods

Aug – Sep

Uttarkashi,

Rudraprayag and

Bageshwar

10.Assam Floods July – Aug

Assam ---

11.Cyclone Thane December

Tamil Nadu,

Puducherry

12.Sikkim Earthquake September

Sikkim, West Bengal,

13.Odisha Floods September

19 Districts of Odisha 45

Sikkim Earthquake 2011 North Eastern India

with epicenter near

Nepal Border and

Sikkim

97 people died (75 in

Sikkim)

15. Cloudburst 2010 Leh, Ladakh in J&K 257 people died

16. Drought 2009252 Districts in 10

States-----

17.Krishna

Floods2009

Andhra Pradesh,

Karnataka300 people died

18. Kosi Floods 2008 North Bihar

527 deaths, 19,323

livestock perished,

2,23,000 houses

damaged, 3.3 million

persons affected

19. Cyclone Nisha 2008 Tamil Nadu 204 deaths

20. Maharashtra Floods July 2005 Maharashtra State

1094 deaths

167 injured

54 missing4th July 2017 18Disaster management

21. Kashmir 2005Mostly Pakistan,

Partially Kashmir

1400 deaths in Kashmir (86,000

deaths in total)

22. Tsunami 2004

Coastline of Tamil Nadu,

Kerala, Andhra Pradesh,

Pondicherry and

Andaman and Nicobar

Islands of India

10,749 deaths

5,640 persons missing

2.79 million people affected

11,827 hectares of crops damaged

300,000 fisher folk lost their

livelihood

23.Gujarat

Earthquake2001

Rapar, Bhuj, Bhachau,

Anjar, Ahmedabad and

Surat in Gujarat State

13,805 deaths

6.3 million people affected

24.Orissa Super

Cyclone1999 Orissa Over 10,000 deaths

25. Cyclone 1996 Andhra Pradesh

1,000 people died, 5,80,000 housed

destroyed, Rs. 20.26 billion

estimated damage

26.Latur

Earthquake1993

Latur, Marathwada

region of Maharashtra

7,928 people died

30,000 injured

27. Cyclone 1990 Andhra Pradesh967 people died, 435,000 acres of

land affected

28. Drought 1987 15 States 300 million people affected

29. Cyclone 1977 Andhra Pradesh

10,000 deaths

hundreds of thousands homeless

40,000 cattle deaths

30. Drought 1972 Large part of the country 200 million people affected

Cascading Effect

• Earthquake

• Tsunami

• Fire

• Nuclear disaster

• Floods

• And so on...

Road Accidents

Vulnerability Profile

Of the 7,516 km longcoastline, close to 5,700km (@76%) is prone tocyclones and tsunamis.

58.6 per cent of thelandmass is prone toearthquakes of moderateto very high intensity.

Over 40 million hectares(12 % of land) is prone tofloods and river erosion.

Disaster Management Act

On 23 December 2005, the Government ofIndia enacted the Disaster Management Act,which envisaged the creation of NationalDisaster Management Authority (NDMA),headed by the Prime Minister, and StateDisaster Management Authorities (SDMAs)headed by respective Chief Ministers, tospearhead and implement a holistic andintegrated approach to Disaster Managementin India.

Functions & Responsibilities• Lay down policies on disaster management ;• Approve the National Plan;• Approve plans prepared by the Ministries or Departments of the Government of

India in accordance with the National Plan;• Lay down guidelines to be followed by the State Authorities in drawing up the

State Plan;• Lay down guidelines to be followed by the different Ministries or Departments of

the Government of India for the Purpose of integrating the measures forprevention of disaster or the mitigation of its effects in their development plansand projects;

• Coordinate the enforcement and implementation of the policy and plans fordisaster management;

• Recommend provision of funds for the purpose of mitigation;• Provide such support to other countries affected by major disasters as may be

determined by the Central Government;• Take such other measures for the prevention of disaster, or the mitigation, or

preparedness and capacity building for dealing with threatening disastersituations or disasters as it may consider necessary;

• Lay down broad policies and guidelines for the functioning of the NationalInstitute of Disaster Management.

Themes of the policy

• Community-based disaster management,including last mile integration of the policy,plans and execution.

• Capacity development in all related areas.• Consolidation of past initiatives and best

practices.• Cooperation with agencies at the national,

regional and international levels.• Compliance and coordination to generate a

multi-sectoral synergy.

Disaster Management Cycle

Prevention and Mitigation&

Capacity Building

Disaster Management

Prepare

Capacity Buildingto deal with new works to deal with

disasters, retrofitting and repair/rehabilitation

Damage/poor maintenance enhances risk of damage/collapse of structures

during disasters

Types of Damages

• Damages could include both Structural and Non-Structural• Non structural damage could include:

• Plaster, • Panel/filler walls, parapets • Doors, windows, window glass panes etc• Dislocation of civil services like water supply, gas, drainage pipes and

electrical conduits/wiring• Disturbed Roofing Tiles• Flooring at ground level, etc

• Structural damage could cover • Foundation system• Load bearing walls • RCC beams/columns• Roofing• Lintels over door/windows, etc

Sequence of Operation

• Removal of Hazardous Components

• Propping & Supporting, wherever required

• Condition Survey to Determine Rehabilitation

• Evaluate Damage to each Structural

Component

• Restoration and strengthening

– Appropriate Structural Repair Method

– Non structural repairs covering civil &

electrical items

• Finish the Repaired Structure

Structural Damage Assessment

• Important to conduct ‘Condition Survey’– Determining rehabilitability i/c part demolition

– Whether building to be got vacated for repairs?

– Detailed damage assessment and determining residual strength.

– Details of temporary support arrangement to avoid further distress under normal loads

Repairs, Rehabilitation and Retrofitting

• In New Building, the extra Cost of SeismicResistant features is nominal (i.e. 2% to 5% ofstructure’s cost)

• In Existing Building, the seismic retrofitting iscostlier (i.e. 5 to 15% of structure’s cost)

• Structural Repairs of Corrosion distressedstructures are also costlier

• Replacement of structure is still more costly• A Balanced View is required to be taken before

deciding upon the various options

Repair & retrofitting Vs Reconstruction

• As a thumb rule, repair/ strengthening is resorted, if its overall cost is less than 30% of the cost of reconstruction

• Replacement/reconstruction is, generally avoided due to

– Preservation of Historical Architecture

– Maintaining functional social and cultural environment

Classification of Repair Materials

• Based on its Application

– Surface Preparation

– Rust Removers / Converters

– Passivators for Reinforcement Protection

– Bonding Agents

– Structural Repair Materials

– Injection Grouts

– Joint Sealants

– Protective Surface Coatings

Cement Concrete/Mortar as

Repair Material

• Cement Concretes/Mortars are the natural Repair Materials for RCC structures but not favoured due to inherent undesirable properties like:

– Drying shrinkage

– Slow Setting

– Low Workability

– Prolonged Curing requirements

– Permeability

Repair Sequence for Corrosion Damaged & Spalled cover Concrete

1. Surface Preparation

• Loose and carbonated concrete removal all-around reinforcement

2. Fix Shear Connectors, if required

3. Apply bonding layer over Substrate concrete

4. Apply Passivating Coat over Steel Reinforcement

5. Apply repair – Cement based repairs or

– Resin based repairs, or

– Sprayed concrete (shotcrete)

Jacketing of RCC Column

REHABILITATION AND SEISMIC RETROFITTING

EARTHQUAKES

• EARTHQUAKES DO NOT KILL BUT IT IS THE BUILDINGS WHICH KILL

• NEARLY 5,00,000 EARTHQUAKES OCCUR EVERY YEAR

• ABOUT 1,00,000 ARE FELT

• Minor earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in Mexico, Guatemala, Chile, Peru, Indonesia, Iran, China, Pakistan, Portugal, Turkey, New Zealand, Greece, Italy, India and Japan, but earthquakes can occur almost anywhere.

CASUALTIES

• LARGE NUMBER OF CASUALTIES OCCUR IN DEVEOPING COUNTRIES. REASONS MAY BE;– INADEQUATE DESIGN

– POOR CONSTRUCTION AND MAINTENANCE

– LACK OF RESOURCES

– INADEQUATE KNOWLEDGE

– INADEQUATE AWARENESS

– INADEQUATE TRAINING

– INADEQUATE SAFETY IMPLEMENTATION

CAUSES OF FAILURE OF MASONRY BUILDINGS

POOR QUALITY OF MORTAR

IRREGULARITY IN PLANE AND VERTICAL DIRECTION

NO PROVISION OF BANDS

NO THOROUGH STONES

HEAVY MASS CONCENTRATION AT ROOF LEVEL

UNSYMMETRICAL BUILDINGS AND FULL OPENINGS

UNCONFINED WALL CORNERS

INADEQUATELY DESIGNED CANTILEVER ELEMENTS

CAUSES OF FAILURE OF RCC BUILDINGS

• SOFT STOREY (ONE IN WHICH LATERAL STIFFNESS IS LESS THAN 70% OF THAT IN THE STOREY IMMEDIATELY ABOVE OR LESS THAN 80% OF THE COMBINED STIFFNESS OF THREE STOREYS ABOVE)

• POOR DETAILING OF BEAM COLUMN JUNCTIONS• PROVISION OF FLOATING COLUMNS• PLAN AND MASS IRREGULARITY• INADEQUATE FOUNDATION• POUNDING OF BUILDINGS• INADEQUATE DESIGN AND DETAILING• INADEQUATE CONNECTVITY LIKE ISOLATED STAIRCASES

AND WATER TANKS NOT PROPERLY ANCHORED

NORMALLY STRUCTURES REQUIRINGREPAIR AND REHABILITATION AREMORE SUSCEPTIBLE TO DAMAGE,HENCE REPAIR AND REHABILITATIONIS VERY IMPORTANT

CAUSES OF DETERIORATION OF RCC

• PENETRATION OF WATER/CHEMICALS LEADING TO CARBONATION, CHLORIDE INGRESS, LEACHING, SULPHATE ATTACK, ALKALI SILICA REACTION ETC LEADING TO

CORROSION IN THE REINFORCEMENT

MAIN REASON OF PENETRATION OF WATER

• POROSITY OF CONCRETE

PRECAUTIONS TAKEN TO PREVENT POROSITY

• ADEQUATE STRENGTH OF CONCRETE

• PROPER COMPACTION

• WATER PROOFING ON ROOF

• PLASTER ON CONCRETE

• WATER PROOFING PAINTS ON EXPOSED PLASTERED SURFACE

CAUSES OF DETERIORATION OF CONCRETE

• AGING OF STRUCTURE

• POOR QUALITY

– POOR QUALITY OF TESTING/INVESTIGATION

– POOR QUALITY OF DESIGN

– POOR QUALITY OF EXECUTION IN TERMS OF MATERIALS/COMPACTION/PAINTS/COVER/RCC

– POOR QUALITY OF MAINTENANCE

SELECTION OF MATERIALS FOR REHABILITATION/ RETROFITTING

• TECHNICAL REQUIREMENTS

• COST

• AVAILABILITY

• EXPERT’S ADVICE

• IMPORTANCE OF THE STRUCTURE

• BALANCE LIFE OF THE STRUCTURE

• TOXICITY OF THE MATERIAL

• AESTHETIC CONSIDERATION

REHABILITATION METHODS

• SAND BLASTING FOR REMOVAL OF CORROSION AND APPLYING A COAT TO RETARD CORROSION

• BINDING/ADDING OF ADDITIONAL REINFORCEMENT/CONCRETE

• WELDING• ANCHORING TO THE EXISTING MEMBERS THROUGH

SHEAR KEYS OR ANCHORS• SHOTCRETING• PLATE BONDING• JACKETING• FIBRE WRAPPING

PROCEDURE

• REMOVAL OF LOOSE MATERIALS/RUST

• PROVIDING PROTECTIVE LAYER/COATING

• PROVIDING BONDING COAT BETWEEN OLD AND NEW MATERIAL/SURFACES

• PROVIDING STEEL MEMBERS/WELDING/ANCHORS/ SHEAR KEYS TO ENSURE MONOLITHIC ACTION

RETROFITTING IN RCC COLUMNS/BEAMS/SLABS

• PLATE BONDING

• FIBRE WRAP TECHNIQUES THROUGH GLASS FIBRES/CARBON FIBRES

• RCC JACKETING

• NEW CASTING

• GUNITING/SHOTCRETING

RCC Jacketing

Carbon Fibre Wrapping

Glass Fibre Reinforcement Wrapping

MS Plate Wrapping

MASONRY STRUCTURES

VULNERABILITY

• BRICK/STONE MASONRY STRUCTURES ARE MORE VULNERABLE AND THEN POORLY CONSTRUCTED/REPAIRED?

• DISASTER= VULNERABILITY X HAZARD

• BRICK STRUCTURES ARE MORE IN THE COUNTRY

• SO WE NEED SAFE BRICK MASONRY STRUCTURES

• IF NOT, WE NEED TO MAKE THEM SAFE BY RETROFITTING.

SEISMIC STRENGTHENING/ RETROFITTING

THE TECHNIQUE TO UPGRADE THE STRUCTUREFOR EARTHQUAKE RESISTANCE TO THE LEVELOF PRESENT DAY CODAL REQUIREMENTSHAVING ORIGINAL STRUCTURAL INADEQUACYOR INADEQUACY DUE TO MATERIALDEGRADATION OVER TIME OR DUE TOALTERATIONS CARRIED OUT DURING ITS USEOVER THE YEARS

SEISMIC STRENGTHENING

MAIN PURPOSE OF SEISMIC STRENGTHEING ISTO UPGRADE/PROVIDE THE SEISMICRESISTANCE ON A BUILDING SO THAT ITBECOMES SAFER UNDER EARTHQUAKEOCCURANCES

AVOIDING THE POSSIBILITY OF BRITTLE MODESOF FAILURE BY PROPER REINFORCEMENT ANDCONNECTION OF RESISTING MEMBERS

IS CODES

◦ IS 13935 (JUNE 2009) – GUIDELINES FOR REPAIR,RESTORATION, CONDITION ASSESSMENT ANDSEISMIC STRENGTHEING OF MASONRY BUILDINGS

GENERAL PROVISIONS REQUIRED IN MASONRY BUILDINGS

PLINTH BAND

LINTEL BAND

ROOF SLAB/ROOF BAND

CORNER REINFORCEMENT

BRICK WORK IN CEMENT MORTAR OF 1:6

RESTRICTED OPENINGS

ADEQUATE FOUNDATION

SELECTION OF MATERIALS AND TECHNIQUES FOR RETROFITTING

CEMENT

STEEL ◦ BOLTS, RODS, ANGLES, BEAMS, CHANNELS,

EXPANDED METAL, WELDED WIRE FABRIC

ADMIXTURES TO IMPROVE NON-SHRINKAGE(GROUTS CONSISING POLYMER, NON-SHRINKCEMENT AND SPECIAL SANDS), BOND (EPOXYRESINS) ETC.

SEQUENCE OF RETROFITTING

REPAIR/REHABILITATION

ALL CRACKS SHOULD BE FULLY REPAIRED

◦ PRESSURE INJECTION OF NON-SHRINK CEMENTPOLYMER GROUT FOR 0.5 TO 5 MM CRACKS

◦ REPAIR BY EXPANSIVE CEMENT MORTAR, QUICKSETTING CEMENT, ADDL. SHEAR OR FLEXURALREINFORCEMENT, STEEL MESH, STEEL RODS

REPAIR/STRENGTHENING OF WALLS

BY GROUTING (CEMENT WATER MIXTURE ORPOLYMERIC MORTAR)

BY ADDITION OF VERTICAL REINFORCEMENTCONCRETE COVERINGS ON THE TWO SIDES OF THEWALL

BY PRESTRESSING WALL

HORIZONTAL SEISMIC BELTS

TO BE PROVIDED ◦ ON ALL WALLS

◦ ON BOTH THE FACES

◦ JUST ABOVE THE LINTEL

◦ BELOW ROOF

◦ BELOW FLOOR

◦ IN CASE OF RCC SLAB ROOF BELT NOT REQUIRED

◦ NOT REQUIRED AT PLINTH LEVEL UNLESS PLINTH HEIGHT IS MORE THAN 900 MM

ON ALL WALLSON BOTH THE FACESABOVE LINTEL

SEISMIC BELTS AROUND DOOR/WINDOW OPENINGS

IN CATEGORY “D” AND “E” BUILDINGS

MESH OF GAUGE 10 WITH 8 WIRES IN VERTICALDIRECTION SPACED AT 25 MM IN A BELT WIDTH OF200MM OR

GAUGE 13 WITH 10 WIRES IN VERTICAL DIRECTIONSPACED AT 25 MM IN A BELT WIDTH OF 250MM (INCAT. C BUILDINGS ALSO)

AROUND OPENINGS

VERTICAL SEISMIC BELTS AT CORNERS

AT THE CORNERS OF ROOMS

JUNCTIONS OF THE WALLS

WIDTH ON EACH SIDE OF THE CORNERTO BE KEPT 25 MM EXTRA TO THEWIDTH OF THE MESH

REIFORCEMENT TO BE STARTED BELOW300 MM BELOW PLINTH LEVEL

AT EXTERNAL CORNERS

VERTICAL REINFORCEMENT AT INSIDE CORNER

ROOFS CONSISTING OF STEEL JOISTS FLAT OR SEGMENTAL ARCHES MUST HAVE HORIZONTAL TIES HOLDING THE JOISTS HORIZONTALLY IN EACH ARCH SPAN SO AS TO PREVENT SPREADING OF JOISTS

ANCHORS

MECHANICAL ANCHORS

CHEMICAL ANCHORS

PROCEDURE OF ANCHORING

SPECIFICATIONS FOR HORIZONTAL SEISMIC BELT

SPEC. FOR VERITICAL REINFORCEMENT

Additional steps

• Repair and rehabilitation to be carried out prior to retrofitting.

• At the external corners, on each face of the wall, the width of the mesh for corner reinforcement may be kept as minimum 250 mm on each wall so that it covers minimum one brick.

• The mesh reinforcement at the corners may be kept minimum 300 mm below ground level

Contd.

• Mesh reinforcement used should be galvanized steeland anti rusting paint should be applied on the cutpoints to prevent corrosion.

• MS washers used on wire mesh should be paintedwith anti corrosive paint. In the present case, M.S.washers of size 50X50X5 mm were used to anchor themesh reinforcement.

• Since it was not possible to provide roof belt of meshof required width in central portion due to segmentalarch construction and ventilators provided near thetop portion, MS flat belt was provided.

•The anchors are to be inserted into thehole after the grout is inserted within geltime, which is given 4 minutes fortemperature of 30 degree Celsius and 6minutes for 20 degree Celsius for theanchors and chemical grout used from HiltiIndia Private Limited.

•In the inside corner reinforcement,a prefabricated MS piece was usedhaving two holes, one used forinserting into the bar which can beadjusted at any position and otherend used for inserting anchor.Chemical anchoring was done

thereafter.Anchoring on wire mesh should bein staggered (zig-zag) manner.

TRAINING, SKILL UPGRADATION AND COMPETENCE DEVELOPMENT

• STAKEHOLDERS

– POLICY MAKERS

– TRAINERS

– PARTICIPANTS

– IMPLEMENTERS

POLICY MAKERS

TRAINERS

PARTICIPANTS

IMPLEMENTERS

Item 1

• Providing and fixing 250 mm wide or required size seismic belt for retrofitting with 12 gauge (2.64 mm dia) galvanized iron welded mesh with 25 mm spacing of wire on walls at required height (inside and out side the building ) fixed in position with headed nails at required distance complete as per direction of Engineer-in-charge. (Cut end of wire mesh to be painted with NitoZinc Primer)

Item 2

• Providing and fixing stainless steel anchors of 8 mm dia(HAS-EM8 x 80 / 14) of HILTI or equivalent on GI wire mesh at required distance in staggered position i/cdrilling of 10 mm dia hole with HILTI hammer drill machine TE-6S or equivalent and cleaning of hole by brush and blow out pump. Anchors shall be fixed by resin and hardener pack of HILTI make HY-150/330/2R or equivalent (35 holes per tube of 330 ml) chemical. Mesh will be fixed with MS washer of size 50x50x5 mm painted with NitoZinc primer (FOSROC) on top of the mesh with anchor screwed with nut complete as per direction of Engineer- in- charge.

Item 3

• Painting on galvanized iron / steel work such as M.S. angle, flat, cold twisted bars with Protective / Bond coats i.e NitoZinc (FOSROC) primer of approved brand and manufacture as per direction of Engineer-in-charge.(Surface area of steel work shall be measured for payment)

Item 4

• Providing and Fixing steel reinforcement bar 10 mm dia for seismic strengthening of building at inside corner i/c fixing with M.S. cleat 50x50x6 mm size having 2 holes. The reinforcement bar shall pass through one hole and other hole shall be used for anchoring into brick / CC wall.

(The payment for steel reinforcement, Anchor & grouting at floor and roof shall be paid for separately)

Item 5

• Providing and fixing seismic band for seismic strengthening of size 50x5 mm flat iron section at required level including making necessary holes not more than 75 cm apart and keeping in position with nails and finally fixing with Anchors ( Payments for Anchors & its fixing shall be made separately).

Item 6

• 28 mm thick Acrylic modified cement mortar/micro concrete band at required level with mix 1:1:2 (1 cement : 1 coarse sand : 2 graded stone aggregate 6 mm & down nominal size) in two coats admixed with polymer modified compound (Armourcrete / Tapecrete) @ 10% of cement (by weight) used area and including slurry coat of Acrylic cement @ 2.2 kg / sqm mixed with polymer modified compound (Armourcrete/ Tapecrete) @ 10% of cement used and finished smooth complete (top layer will be of 12 mm plaster).

Photos and References have been taken from various web sites.Their contribution is gratefully acknowledged)

Disaster management and seismic retrofitting

Engineering