Seismic Evaluation of Existing Buildings

Abstract

Open ground storey buildings are commonly provided in India since they provide much-needed parking space in an urban environment. These buildings are observed to be the most vulnerable type of vertically irregular buildings. NCT Delhi has been chosen as the area of study due to availability of microzonation study. Most of the buildings in Delhi are open ground storey. The Model Building Bye-Laws 2016 of Delhi direct plot owners to accommodate all vehicles inside the plot area in order to avoid traffic congestion on the road. FAR norms are relaxed for buildings with stilt parking. So owners opt for it. Again some buildings are designed for only gravity loads. Delhi lies in Seismic Zone IV of the Seismic Zoning Map of India. But as per microzonation study conducted, different parts are assigned different zones from III, IV, V based on their PGA values. Few sites have even more PGA than that assigned to zone V. Delhi lies in a region liable to moderate damages. Earthquake occurring in Himalayas also affect Delhi. The project aims to find the vulnerability of various types of buildings with different storeys, bays, etc. in various parts of Delhi. Vulnerability assessment of two G+4 storied buildings having different plan dimensions, both located in Wazirabad, have been taken up. Fragility curve of the buildings are obtained using Incremental Dynamic Analysis. Hazard curve is plotted for the selected site in Delhi. Collapse risk is estimated for the buildings by convoluting fragility curves and site specific hazard curve.