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One crack, a tremor, a loud sound…and collapse! Buildings fall. This is true to India, and the string of accidents reported in recent years is testament to this. Consider this: Last September, five people were killed after an apartment block collapsed in Delhi; months earlier, a six-storey building collapsed on the outskirts of Delhi, killing nine; in March, a four-storey, under-construction building collapsed at Dharwad in north Karnataka. These are just some recent mishaps â€� unfortunately, there have been more. In fact, millions of Indians live in dilapidated buildings at the risk of collapse during the rains. Recent reports have indicated some statistics from the busy cities: Mumbai has 4,299 dilapidated buildings, of which, 633 come under the C1 “extremely dilapidatedâ€� category; the Bruhat Bengaluru Mahanagara Palike has so far identified 52 structures that are in a dilapidated state and run the risk of collapsing; last year, Kolkata Municipal Corporation issued notices to 52 old and dilapidated buildings located in different areas under its jurisdiction. What’s more, the condition and quality of the Indian building stock is poor when it comes to seismic performance and fire-outbreaks. What leads to a collapse? The reasons are often related to planning, design and material. The use of inferior construction material is believed to be the root cause that reduces the life of a building. Some common causes for collapse today, according to Dr Paresh Shah, Professor & Dean, Faculty of Technology, CEPT University, are “improper geotechnical investigation; poor quality RCC construction practices; and improper formwork practices, inadequate stripping time, lack of re-shoring or shoring to lower floors.â€� According to Dr Pramod Kumar Gupta, Professor, Structural Engineering, Department of Civil Engineering, IIT-Roorkee, “In planning, we have to check the load transfer mechanism. Here, the external load, which may be owing to gravity or earthquake, should be transmitted to the foundation without creating any structural damage to the structural elements. The foundation should be strong and stiff enough to transfer the load to the soil or earth. So, an appropriate structural form may address this issue.â€� Dr Gupta adds that before designing any structure, an analysis is carried out, where reactive forces and associated deformations in different structural elements are determined using appropriate techniques. Thereafter, the design of elements is carried out by choosing a suitable material. “Choice and quality of material are key parameters these days and proper quality control should be ascertained when it comes to material,â€� affirms Dr Gupta. In his view, if all these steps are followed with due care, it would be near on impossible for any structure to collapse before reaching its age. SHRIYAL SETHUMADHAVAN