STRUCTURAL FAILURES-CAUSES AND REMEDIES: B.NAGU NAIK CH.ARUNA G.S.S.SAI KALA GVP COLLEGE OF ENGINEERING (A)

Technically a failure is defined as STRUCTURAL FAILURE : Occurs when building loses its ability to perform its intended design function. Technically a failure is defined as “an unacceptable difference between expected and observed performance”. Occurs when overstressed construction reaches a critical stress level.

TYPES OF STRUCTURAL FAILURES : Failure during construction Failure due to failure of services Failure due to improper maintenance

CAUSES OF FAILURE (CONTROLLABLE): Errors in designs Improper selection of materials Poor workman ship Formwork failure Geotechnical failure Failure due to improper maintenance Technical failure

Important technical failures : Structural cracking : foundational cracks, wall cracks, floor or slab cracks. I f crack width is between 15-25 mm , the degree of damage is considered as “severe”.

Improper design mix: Structure unable to attain designed compressive strength. Water –cement ratio must be within acceptable limits Grade of concrete should be chosen in such a way that it should bear the designed load.

Remedies to prevent structural failures : Design of structure should satisfy Stability Strength Serviceability Deflection of beam or frame should be thoroughly checked for safe design. Corroded reinforcement expands and cracks concrete cover. To avoid this proper cover and water quality should be maintained.

Case study -1 : TACOMA BRIDGE COLLAPSE Failure occurred in 1940 due to lack of resistance torsionalforces. Principal causes: Excessive flexibility Drag and lift forces created solid plate girder and deck acted like an aerofoil Wind load forces were not taken into account during designing Resonance

Case study – KOLKATA FLYOVER COLLAPSE Rcc deck over plate girder collapse of 100m section . Lack of quality check Inconsistency in construction material Faulty approval of design Delay in construction.

Safety in design aspect. Should be clear with properties of concrete. CONCLUSION : Upon observing a lot of failures in and around us, we being future building professionals we should never compromise on Safety in design aspect. Should be clear with properties of concrete. Fundamentals of engineering should be applied on all design aspects. Overlooking the design of even minute parts should be avoided.