by THO
A 4.0 magnitude earthquake struck Delhi early this morning, causing panic among residents. Those living in high-rise buildings, particularly in Noida and Ghaziabad, were alarmed, with many fearing for their safety amid growing concerns of potential aftershocks and further seismic activity.
With Delhi-NCR becoming a hub of high-rise buildings, some as tall as 29 floors if not more, here’s what residents should know about high-rise safety.
While most high-rise buildings have incorporated advanced technologies, structural design experts say that buyers planning to buy into a high-rise or those already residing in one should not get confused with statements like “the building has been designed to Zone 5 or Zone 4 standards”. Zones depict the seismic hazard, and the earthquake-resistance category talks about the seismic performance of a building.
If you plan to buy an apartment in a high-rise building and the brochure mentions that the building is earthquake-resistant, you should be aware that those who claim to build and sell quake-resistant buildings simply mean they have followed standard regulations.
Ideally, says Abhay Gupta, director at Skeleton Consultants Pvt Ltd, advertisements that claim a project is earthquake-resistant should mention the name of the structural designer, the IS code number, and declare that the building has been designed for earthquake zone 4.
Earthquake-resistant buildings, their categories and more
In India, buildings are sold, leased and rented by just mentioning that the structure is quake-resistant, without specifying the “category of resistance, i.e. fully operational, immediate occupancy, life safety or collapse prevention”, said Sandeep Donald Shah, a structural engineer from Miyamoto India.
There are four types of earthquake-resistant buildings: Type A is operational, Type B is immediate occupancy, Type C is life safety, and Type D is collapse prevention. Type A is the best, and Type D is the lowest. Occupants need to know which category their building falls in, said Shah.
Category A buildings may not incur any damage in case of an earthquake. Category B refers to buildings that may experience cosmetic damage but zero structural damage. Category C buildings can be damaged by the aftershocks of an earthquake, but the damage is repairable. Category D buildings are beyond repair and may have to be razed, he explains. He says the difference between the four categories is so wide that keeping a customer in the dark is a blatant breach of a consumer’s right to be informed and to consumer education.
He explains that a Type B building will typically cost approximately ₹350 per sq ft more than a Type D building. However, a Type B building will have minimal structural damage and be structurally safe to occupy and use even after a major earthquake.
“There should be strict rules that all buildings, both new and old, should have engraved metal plates of size not less than one foot by two feet, mentioning that the building is earthquake resistant, collapse prevention or any other category or ‘earthquake-resistance unknown’,” he says.
Shah says that a 2014 Supreme Court order acknowledged that people should be made aware of earthquake safety and the different categories of buildings and that the builder should mention the category in the advertisements, but unfortunately, these directions have not been implemented.
“Most buildings do not have earthquake alarms. Ideally, all high-rise societies should conduct drills akin to fire safety drills on a regular basis but this too is not done,” he adds.
Definition of an earthquake-resistant building
Other structural engineers point out that India doesn’t have a definition of earthquake-resistant structure even though building collapses and earthquakes are reported regularly. The building design codes and the Real Estate (Regulation and Development) Act of 2016 are silent on it.
In India, most high-rises are built according to local bylaws and the National Building Code, which is considered safe to withstand earthquakes. As most of India is located in seismic zones, experts say it is important for builders and authorities to ensure that construction meets earthquake standards.
Buyers should do their due diligence
Having said that, there is no substitute for due diligence. Buyers should ask questions about structural safety before buying or renting and ensure the earthquake-safety promise is more than an advertising gimmick. Before booking a flat, a buyer should find out who the structural designer and the soil consultant of the project.
“An architect is only not responsible for the durability and the strength of the structure,” explains Gupta.
Buyers should ask for a building’s soil report, structural design and drawings, he said. That’s the best way to gauge a building’s strength.
Also, check the construction quality for which a buyer or a group of them can together hire a structural expert. The cost can vary from ₹25,000 for a single buyer to around a few lakhs for the entire building.
Generally, concrete buildings have a life of 50 years but considering the quality of materials used, the buildings start deteriorating within 15 to 25 years. This is why RERA should call for an examination of the structure of a group housing project after 10 years and then every five years, explains Gupta.
If you are planning to buy an apartment on the higher floors
Make sure that IS codes 16700, 456, 1893, 13920 among others have been adhered to. These are codes for the safety and construction of buildings, including those that are higher than 50 metres, says Gupta.
If you are buying an apartment above the 20th floor, make sure you get the building movement tested. The wind force is extremely important, especially in the event of an earthquake. During an earthquake, a building undergoes lateral movement, which is why loose furniture is often not recommended for higher floors, explains Gupta.
Experts also point out that buyers should check the quality of windows, and the first test is to ensure there is no humming sound.
