Most residents of high-rise apartments in the upscale suburbs of Delhi rushed out of their homes at 4:42 am last Monday when an earthquake measuring 4.3 on the Richter scale struck 10 km away near Bahadurgarh on the Capital’s western border with Haryana. Mercifully, no damage was reported from anywhere.
But, the question is: are we waiting for disaster to happen to jolt us out of our slumber? With high-rises becoming the norm of the day, how do buyers check that the building in which they are booking their dream home in is earthquake-resistant. Every developer firm today advertises that its project follows an earthquake-resistant design. But, that can only be verified when – God forbid -- an earthquake of high intensity strikes your apartment building. By then, it could be too late!
Says Anita Puri, Assistant Chief Architect, Ansal Buildwell Ltd., “The Bureau of Indian Standards (BIS) lays down different criteria for different earthquake prone zones in the country. Registered structural engineers give projects a ‘structure certificate’, copies of which we give to the buyers as well at the time of booking. In fact, the structural engineers oversee the construction of the projects from time to time to ensure that the laid-down standards are adhered to.”
Buyers must ensure that the builder gives them the ‘structure certificate’ and can, if they want, check if earthquake resistant elements (in the foundation, depth of the project, reinforcement of walls, plinth beams etc.) have been incorporated. For a clearer understanding, some of the less known facts about earthquake protection of buildings are:
There is no such term as “earthquake proof” as no building can be entirely safe from earthquakes. The actual term to be used is “earthquake resistant”, which means that minimum damage to life and property is caused following an earthquake.
Earthquake resistant design as per the Indian Seismic Code is the minimum permissible earthquake protection to be followed in the country. The Indian code gives freedom to users to design for higher levels of protection.
When a developer advertises that a building has been constructed to earthquake-resistant specifications, it means that they have followed the minimum permissible safety standards. So, even if they don’t follow higher levels of protection, it is not mandatory.
Earthquake resistant buildings in India be it in Zone III, IV (in which Delhi falls) or in Zone V are designed for what in industry terminology is called ‘Collapse Prevention’. The minimum standards being followed in the developed markets of the world is ‘Life Safety’ – which is in a category higher than what is being followed n India.
In India, buildings are so designed to prevent a total building collapse. However, there may be a loss of life due to falling masonry walls etc. “Therefore, a typical earthquake-resistant building in the country will sustain extensive structural damage during a major earthquake,” says Sandeep Donald Shah of Taylor Devices, a company specializing in technology used for earthquake- resistant design.
After an earthquake, the owner/user will have no option but to demolish and re-construct the building.
‘Life Safety ‘design i.e. minimum design being followed in most countries except India, does not permit the use of un-reinforced masonry walls.