Performance of Buildings Using Site Specific Ground Motion of Kolkata, India

Kolkata, capital of West Bengal, India, is presently congested with moderate to high rise buildings, and may undergo damage during future earthquakes due to the amplification of seismic waves by the soft alluvial soil. Further, most of the buildings are open ground storey (OGS), which is very vulnerable to earthquakes. Therefore, in the present study, the performance of some typical G+1, G+4 and G+9 storied buildings are analyzed using the available site-specific time history of the city by non-linear time history analysis (NLTHA). The analysis has been carried out for maximum considerable earthquake (MCE) and design basis earthquake (DBE) by both considering the stiffness of the infill wall (WI) and without considering stiffness of infill wall (WOI). The result signifies that, in almost all locations, the percentage of roof displacements obtained by site specific time history are more than the Indian codal compatible time history for both WI and WOI. Thus, performance will not be satisfactory for the buildings which are designed according to the Indian seismic code. The present study also corroborates that for almost all the buildings, the ground storey drift remains below immediate occupancy (IO) level during DBE and it varies IO to life safety (LS) level during MCE. However, all the storey drift are below Collapse Prevention (CP) limit. It is to be mentioned that for all the buildings the inter storey drift is higher than the Indian codal (IS-1893 (Part 1):2016) permissible limit (0.4%) during both DBE and MCE. However, the storey drifts result for WI buildings are comparatively lower than WOI buildings which are due to addition of stiffness of infill in each floor and fundamental modal spectral acceleration is lower.