failure & distress of structures.pptx

7/29/2019 FAILURE & DISTRESS OF STRUCTURES.pptx

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FAILURE & DISTRESS OF

STRUCTURESCAUSES & REMEDIES

BY

Prof.(Dr.) Sudhendu SahaChartered Professional Engineer


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Common Nature of Failures and

Distresses

Foundation Failure

Excessive settlement, tilt and collapseDistresses in structural elements like

beam, column & slab

in forms of cracks, corrosion etc


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Case Histories Damage caused to connecting fire fighting

pumps due to excessive settlement and tilts

of the above ground fire water storage tanks

Tilting of overhead water reservoir

Failures of RCC bored cast in situ piles to

take the design load during load test

Failures of RCC bored cast in situ under-

reamed piles during load test

Excessive settlement of storage tanks on

ground treated with stone columns


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Tilted Overhead Tilted

Tilted Overhead Reservoir


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Excessive Settlement of Silo


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LEANING TOWER OF PISA


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Tilted Trestles of Conveyer


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Collapse of Soft Storey


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Collapse of Soft Storey Bldg at Car Nicobar


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Collapse of Soft Storey of Building


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Collapse of Building Under Construction


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Materials do not fail. They follow

the laws of nature and physics

perfectly according to their basic

properties and characteristicsbasic types of human errors :

Errors of knowledge (ignorance)

Errors of performance (carelessnessand negligence)

Errors of intent (greed)


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Errors of performance (carelessness

and negligence)

Carelessness in Design & DetailingsCareless Construction

Careless Project Management

Carelessness & Negligence of PMCNegligence & Poor Maintenance


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Common Nature of Failures and

Distresses

Excessive settlement, tilt and collapse

Distresses in structural elements offoundation like beam, column & slab

in forms of cracks, corrosion etcaffecting durability and satisfactory

performance


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Excessive Settlement of Silos


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Differential settlement of Pisa Tower


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TILTED OVERHEAD RESERVOIR


18/41PLAN OF TILTED OVERHEAD RESERVOIR


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Layout of Ground Settlement Control


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Elevation of Tilted Overhead Reservoir


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Causes of Failures or Distresses

Design,Detailing and drafting.

Specifications of Materials& Methods of Construction

Workmanship

Poor Supervision & InspectionUnexpected Natural Disaster


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Poor Construction Practices

Improper selection of materialsSelection of poor quality cheap materials.

Inadequate control on Batching, Mixing,

Transporting, Placing, Finishing and CuringImproper construction joints or between

concrete framework and masonry

Addition of excess water in concrete andmortar mixes

Indiscriminate addition and alterations


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Concrete consists of different

materials & Processeses

Cement, Sand, Aggregates,

Water,Admixtures, Batching or Mixing,

Transportation, casting,

Compaction,

Vibrating, Curing


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Poor Masonry Practice


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Corrosion of Reinforcement

concrete cover

concrete around it is

impervious and does notallow moisture or chlorides

high pH value


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Concrete Disintegration

Mechanisms occur with

Exposure to Aggressive

ChemicalsAlkali-Aggregate Reactions

Sulphate Attack andChloride Attack


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Repairing reinforcement corrosion

removal of carbonated concrete

cleaning of reinforcementprotection coat

making good the reduced steel area

applying bond coat and cover

replacement


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Distresses in Concrete Structures

Corrosion of Reinforcement

Cracks

SpallingLeakage

Chemical attack

Effects of Environment


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Causes of Distress in Concrete

StructuresHigh Water / cement ratio

Inadequate curing

Poorly graded aggregates

Inadequate compactionShuttering joints not slurry tight

Less cover thickness

Wrong placement of reinforcementChemical attack by Chloride,

Sulphate, etc.

Wrong design and details


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Classification of causes of failures

or distresses

Unpredictable

Design

Detailing and draftingMaterials

Workmanship

Inspection & Supervision


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Failures may occur during expected

service periodUse of the building for the purpose other

than for which it was designed.

Overloading and misusing the building.

Poor periodic maintenance and not

attending to cracks and minor distress in

time


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Indiscriminate addition

and alterations


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REPAIR OF DISTRESSES

Structural strengthening by PlateBonding, RCC Jacketing, Propping &

supporting, etcFoundation strengthening can bedone by UnderPinning by Piles,Micro-piles, Inject of ground by

cement or chemical grout etc.Cathodic Protection


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Spalling of Concrete


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Corrosion of steel in a canopy


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Corrosion & Spalling


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Cracks in Column & wall


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Possible Slip of Bridge Supports


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Corrosion affected Distressed Column


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Beam-Column Joint Failure


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Beam-Column Joint Failure

failure & distress of structures.pptx

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