EARTHQUAKE BEHAVIOURAL ANALYSIS OF BASE ISOLATED STRUCTURES USING FRICTION PENDULUM BEARINGS

Abstract

The present work attempts to study the effectiveness of base isolation using friction pendulum bearings (FPB) over conventional construction, using a hypothetical case study of identical conventional and isolated buildings constructed in the most seismically active region in India (Zone V). It is seen that the base isolated building exhibits excellent performance compared to the conventional ductile building. The modeling procedure for both fixed base and base isolated building in ETABS software is carried out for a regular (G+8) storied MRF building. Linear analysis using Time History Analysis (THA) for the records of Kobe earthquake, 1995 and Non linear analysis using Incremental Dynamic Analysis (IDA) was carried out. For IDA, incremental intensities of 0.2g, 0.4g, 0.6g, 0.8g, 1.0g and 1.2g for the previously considered Kobe earthquake were taken as input. It was observed that the variation in maximum displacement of stories in base isolated model is very low while compared with fixed base model, with the isolated frame exhibiting higher displacements. However, the interstorey displacements and drift were comparatively reduced leading to a safe design. It was also observed that storey overturning moment & storey shear exhibit a similar trend in base isolated building. The radius of proposed FPB are calculated using a suggested by Naeim, 1999 and comments were made on the overall feasibility of the proposed isolation system.