Seismic Fragility Analysis of Base-Isolated Buildings resting on Sloping Ground under real earthquake ground motions

Most of the hilly regions are situated in high seismic zones of India. Such a threat compels the need to keep a check on the performance of buildings that suffer extensive damages or even collapse during strong ground shaking on account of near-fault pulses. The present research work is related to the construction of an ensemble of fragility curves for buildings lying on 15⁰, 30⁰ and 45⁰ slopes. In order to mitigate the damages caused by near-field earthquakes, base isolation system using lead rubber bearing has been provided at the foundation level. The responses of the buildings are obtained by incremental dynamic analysis and linear regression is performed to obtain the probabilistic seismic demand models to find out the median intensity and the uncertain parameters. All the buildings are analysed for slight, moderate, extensive and collapse damage states for which the corresponding fragility curves are obtained. Base isolator was able to significantly reduce the seismic demand measures by imparting flexibility to the system and therefore can be recommended as an alternative to conventional fixed base type buildings located on sloping terrain experiencing near-fault motions.