Building Failures and its Causes- Theory of structures

BUILDING FAILURES AND CAUSES: CASE STUDIES

Theory of Structures

Introduction • What does a structural failure mean?

– Building failure occurs when the building loses its ability to perform its intended (design) function. Hence, building failures can be categorized into the two broad groups of physical (structural) failures (which result in the loss of certain characteristics, e.g., strength) and performance failures (which means a reduction in function below an established acceptable limit) (Douglas and Ransom, 2007).

General causes of failure• Failure of a structure can occur from many types of

problems, mostly unique to the type of structure or to the various industries.– Due to size, shape, or the choice of material, the

structure is not strong and tough enough to support the load. Failure can occur when the overstressed construction reaches a critical stress level.

– Instability, whether due to geometry, design or material choice, causing the structure to fail from fatigue or corrosion. These types of failure often occur at stress points, such as squared corners or from bolt holes being too close to the material's edge, causing cracks to slowly form and then progress through cyclic loading. conditions.

– Manufacturing errors, may be due to improper selection of materials, incorrect sizing, improper heat treating, failing to adhere to the design, or shoddy workmanship.

Man made v/s natural causes• Most of the structural failures are associated with materials and are the consequence of

human blunder involving a lack of know-how about materials or the combination of contrary materials.

• There are structural failures that can be endorsed to irregularity in materials. Although too much reliance is given on modern structural materials yet the manufacturing or production faults may exist even in the most dependable structural materials, such as standard structural steel or centrally blended concrete

V/S • One of the major natural factors that result into building collapse is rainfall; others may

include temperature, pressure, etc. • When there is a heavy downpour of rain, there is a possibility that one or more

buildings(completed or uncompleted), somewhere , would cave in (Chinwokwu, 2000). • The fact remain that this is a natural factor that cannot be stopped, buildings therefore

need to be constructed adequately bearing in mind such uncontrollable factors.

City-Specific reasons • Property prices and rent in Mumbai are among the highest in

Asia. Many citizens are forced to live in old, dilapidated properties in a land-scarce city.

• And between 2008 and 2012, there were 100 building collapses in the city in which 53 people died and 103 others were injured, authorities say.

• The gradual decay of buildings is most commonly a result of the lack of periodic maintenance, especially when the buildings fall under the Rent Control Act.

• Building collapses are common in India due to – substandard materials– inadequate supervision in constructing multistorey structures.– The incidents have highlighted shoddy construction and

violations of the building code, amid burgeoning demand for housing in many parts of India and endemic corruption.

• Adjoining is a timeline of building collapses in Mumbai in 2013, published in The DNA newspaper, dated 28.09.2013

Case study 1: Collapse due to human error• ‘Canacona building collapse: Weak columns, strong beams

reason for disaster‘: January 8, 2014– The under-construction five-storey building crashed killing

18 workers, injuring 14 more. – Poor workmanship, lack of soil analysis and substandard

quality of construction materials may have been largely responsible for the tragic collapse of this building in Ruby residency in Chaudi, Canacona.

– The debris of the collapsed building shows some beams and slabs sitting on top of each, but not a single column. "All the columns have been reduced to powder at the site," a source said. It could be a case of weak columns and strong beams.

– Sources said m20 grade of concrete appears to have been used for the columns. "It is okay for the slabs but not columns and m25 grade would have been better," another source pointed out.

Case study 2: Altaf Manzil,Mahim• Altaf Manzil, the five-storey building on Cadell Road

collapsed late on Monday night after it rained heavily in the city. A portion of the five-storey building caved in, apparently due to rain, in Mahim.

• The Altaf Manzil building, that stands next to several other old buildings, was built in 1984, and had never since received any renovation.

• A car showroom that had come up in the ground floor of the building. The car showroom had made structural changes to the basement by removing several pillars. This is what probably caused the disaster, said a resident. A seven tonne hoarding on top of the building could have also added to the risk, reports say.

• The building however, was already on BMC’s list of dilapidated/dangerous buildings, due to the weakening of members as a result of monsoon lashes.

General precautions/ measures

• Water cement ratio is to be controlled. • Reasonable pace of construction adopted.• Brick work over load bearing RCC members should be done after removal of shutting

giving a time gap.• Brick walls between columns should be deferred as much as possible. • Plastering of areas having RCC and brick members should be done after sufficient time

gap say one month or suitable groves provided in junction.• Corroded reinforcement expands and cracks the concrete cover. To avoid this

phenomenon rich mix of concrete using proper quality of water and adequate cover should adopted.

• Avoid bricks containing too much soluble sulphates (more than 5 %) and use rich mortar in such cases.

• Use expansion and control joint at closure intervals.

• Large trees growing in the vicinity of buildings cause damage in all type of soil conditions. If the soil is shrinkable clay cracking is severe.

• This can be solved by taking precautionary radius around any present vegetation, as non- buildable area.

THANK YOUGarima Rajput 43Manasvi Rane 44Rithika Ravishankar 45Shweta Salam 46Shivali Sanap 47Vishakha Savatkar 48