Limitation of Inter-Storey Drift Ratio in Seismic Design of Lead Rubber Bearing Isolated R. C. Building

Abstract

AbstractEffects of inter-storey drift ratio of base isolated R. C. Structure on design of seismic resistant building have been a major subject of research in the last two decades. In this paper, the influence of design inter-storey drift (IDR) ratio on the achieved IDR base isolated buildings is analysed. Lead rubber bearing are designed as per UBC-97 guideline and used as a base isolator for this study. Base isolated structures are designed for inter drift ratio range from 0.1 to 2.5% as per the SEAOC 1995 [version 2000] using direct displacement basedesign method (DDBD) for three different heights 4-storey, 6-storey, and 9-storey, and each having a different building plan. Dynamic time history analysis (THA) is conducted to study the seismic responses of the respected 40 numbers design isolated buildings. It was observed that, building with higher storey shows more achieved inter drift ratio compared to low storey, the maximum inter-storey drift achieved by an isolated building is not more than a 0.5%, even in cases where the design inter-storey drifts are more than 0.5%. With the current design methodology, it will not be effective if the design IDR is more than 0.5%. More study is required to develop a better correlation between design and achieved IDR.KeywordsDirect displacement base designLead rubber bearingUBC-97Inter-storey driftIsolated building