EATRHQUAKE RESPONSE OF REINFORCED COCRETE MULTI STOREY BUILDING WITH BASE ISOLATION

Abstract

A seismic base isolation is an earthquake resistant design method that is based on reducing the seismic demand and also the ductility demand. The basic concept of base isolation system is to increase the natural time period of the fixed base building and to protect the structure from the seismic effect. The main purpose of this work is to study the dynamic response of structure when subjected to different isolators. For this purpose, a three dimensional response spectrum analysis and time history analysis is performed using a commercial structural analysis software package called as SAP 2000 to study the influence of isolation damping on building. The main objective is to make a comparison between the fixed base building and various isolation systems such as friction pendulum isolator, lead rubber bearing (LRB) isolator and high damping rubber isolator, subjected to strong earthquakes to achieve an optimal design of the base isolation system. SAP 2000, a popular large scale explicit finite element analysis software used to stimulate the behavior of base isolated structure. In the present work, it was found that base isolation substantially increases the time period of structure and hence correspondingly reduces the base shear. The top displacement for fixed and isolated cases conspicuously shows the reduction in the case of isolated frame. The study shows that the bending moment and shear force values are reduced for base isolated frame when compared to fixed base building. From design consideration the steel requirement is reduced in base isolated structures when compared to fixed base building. Key