Effect of Bracings on the Seismic Response of a Soft-Storey Structure

Abstract

A majority of the urban areas are growing vertically due to the crunch of horizontal space. This has led to the construction of numerous multi-storied buildings with an open ground storey for the provision of parking space for vehicles. This makes the first storey relatively less stiff compared to the upper stories which are stiffened by infill walls, thereby causing a sudden decrease in lateral stiffness. Recent and past earthquakes all over the globe have shown large number of such reinforced concrete buildings vulnerable to damage or even collapse during an earthquake. In this study, an existing soft storey reinforced concrete building located in Hyderabad was analysed using linear time history analysis considering the ground motion from Bhuj Earthquake (Mw=7.7). Bracings are incorporated at selected locations to stiffen the ground storey. The response of the structure was studied for different cases viz., (a) Neglecting infill strength and stiffness (b) Considering infill strength and stiffness and (c) structure with bracings in the ground storey. A comparative study of these cases is carried concerning storey displacements, storey drifts, the response of building roof and peak base shear. The results depict that the bracings significantly help in reducing the global response of the structure.