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404 structures in Bengaluru are structurally weak: BBMP survey

With continuous rain in the city, there are reports of buildings collapsing and tilting, and residents of several buildings are having sleepless nights

Published: 18th October 2021 06:34 AM  |   Last Updated: 18th October 2021 01:52 PM   |  A+A-

A building collapsing in Kamalanagar. (Photo | Nagaraja Gadekal)

A building collapsing in Kamalanagar. (Photo | Nagaraja Gadekal)

Express News Service

BENGALURU: It’s been two years but still residents of Hutchins Road dread every loud sound they hear. They are still haunted by the memories of the collapse of two apartment buildings in July 2019 in which five including a child were killed. With continuous rains lashing the city and a series of building collapses, residents of several buildings, some of them newly constructed apartments, are having sleepless nights. In Silicon City Bengaluru, as per the freshly done survey by Bruhat Bengaluru Mahanagarapalike, there are as many as 404 buildings that are structurally weak and can collapse at any time.

"I saw people dying in front of me. Even to this day, I wake up with a panic attack. It was late in the night around 1.30 am. I still remember that loud sound and how the floor shook. I ran along with my family banging the doors of all houses in my apartment asking them to run downstairs. Bengaluru has not learned its lessons. We are seeing so many buildings collapsing, tilting. It's scary. Officials need to take this seriously before history repeats," says Rajesh Nath (name changed) who once lived in the Sai Adi Ambal apartment which collapsed in July 2019.

With the spell of rains in the city, in less than a month, there has been a spree of building tilts and collapses in Bengaluru. However, BBMP has only managed to demolish 10 such unfit buildings. Some of the zones like East, South and West are said to have more than 90 structures that are in a bad shape. Speaking to TNIE, Chief Commissioner, Gaurav Gupta said, "Apart from the 2019 survey, another 300 plus buildings have been identified and a follow-up is being done on the same. The eight zonal officers and 27
divisional officers have been asked to check and reach out to the owners of the building and even the residents and inform them on the same. There are incidents where people do not want to listen to us and state that the building is safe. However, we have the right to issue notice to such owners and action will be taken."

He further added, "Immediate action will be taken to demolish such structures. The sudden collapse has happened due to the continuous rains and improper foundation of these buildings."

Sadly, every time such an incident occurs, authorities activate a familiar drill: an inquiry is announced, blame is passed around, and the matter is forgotten even before the debris is cleared. The main issue of why so many structures are sliding into disaster remains unaddressed.

According to experts, some of the major reasons for the collapse is that someone who constructs a building on his site doesn't follow the rules laid before any building is built. They pointed out that though the rains have been blamed for the sudden collapses, one should know that buildings are constructed to withstand any climate condition. "Widespread misuse of building bye-laws, designated floor area ratio(FAR) and unauthorised additions have resulted in larger buildings, modified over time, resulting in unsafe conditions," Naresh Narasimhan, Architect and Urban Designer from Bengaluru, said.

Explaining how it is not the rains or soil erosion that is an issue Sujay Ghorpadkar, Principal Architect at Opus Architects, Fellow at Indian Institute of Architects (IIA) Says, while there are multiple reasons for a tilt in the building or a collapse, the owner of a site has to first do certain things before he/she plans for construction.

The first is to ensure that he goes to a qualified architect who in turn can employ a certified structural engineer who prepares a proper structure plan and by the end of the project is in a position to give a structural stability certificate.

Experts warn that builders, site owners don't seek inputs on surveys, soil investigations and geo-technical parameters. They say that it is very important to determine the soil strength in the site area before commencing planning and construction.

"To properly characterise a building site and to design a foundation that will support a structure, it is a must to understand the types of soil deposits that will support the foundation. Rarely is the soil homogenous, and the soil profile will vary with depth and may vary across the site as well. To do this, a Soil Test Boring is done to gather subsurface information. At least three boreholes at the site have to be done for this information," explains Sujay.

As this can get expensive, many people compromise on this report and get the soil test done only at one location of the site or don't go for this test at all, he says.

Meanwhile, loading factors also need to be considered, says Sujay. The size of the concrete column is extremely important. A minimum of 8 inches is a must but many builders, to save money, do a six-inch concrete column with insufficient steel which causes the newly built buildings too to break.

"That is what has probably happened in the Kasturi Nagar building collapse case. Insufficient steel with less than an 8-inch column is the main culprit. Anyone buying an apartment complex or a house need to watch for this," explains Sujay.

Other reasons he says are setbacks not being met, deep excavations not planned well and illegal floors. Meanwhile, V Ravichandar, Bengaluru based Urban Infrastructure expert says unprecedented rains during recent times are an additional stress.

"Many of the foundations are not designed to take the kind of overbuilding that is done, that is one floor over the other. Many of the buildings are built on low-lying areas. The foundation structural characteristics need to be taken care of where the soil needs to be soft and anchored. Any shortcuts in construction will require paying a price. One needs a civil engineer to build who has subject matter knowledge but now there is everyone getting into it," he said.

The experts also called for the civic body to carry out frequent surveys to see the fitness of buildings is important.

"Just like there is the car policy, where cars need to be scrapped after 15-20 years, every two decades a survey needs to be done on vulnerable buildings which is essential," Ravichandar added.



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