SEISMIC RESPONSE OF MULTISTORY BUILDINGS USING FRICTION PENDULUM SYSTEM

Abstract

In seismic base isolation, the superstructure is decoupled from the earthquake ground motion by introducing a flexible interface between the foundation and the base of structure. Past study has revealed that friction pendulum system (FPS) can be a better alternative in the base isolation system to study the response of building for strong earthquake ground motion. The friction pendulum system is a sliding type seismic isolation system, which uses its surface curvature to generate the restoring force from the pendulum action of the weight of the structure on the FPS. Therefore in this thesis the attempt has been made to check the suitability of the friction pendulum system (FPS) for multi-story buildings. The study includes modeling of friction pendulum system and numerical analysis of multi-story buildings subjected to earthquake ground motion. The force-deformation behavior of the isolation system is modeled by the bi-linear behavior, which can be • effectively used to model all isolation systems in practice. Roof acceleration response of friction pendulum system (FPS) has been compared with fixed base structure for three earthquakes. Maximum displacements and accelerations have been compared at each story level for three earthquakes. The effect of isolation damping is very important in overall performance of buildings. The variation of the top floor absolute acceleration and . • bearing displacement of the isolated building is studied under different damping percentages of the isolation system. The effect of isolation damping on the response of buildings has been analyzed by varying effective damping of FPS from 5% to 35% for five different spectrum compatible time histories. Parameters considered are bearing displacement and absolute roof acceleration because bearing displacement is important • for the design of isolators and roof acceleration is important with respect to the force , • attracted by the superstructure.