Optimization Study of Isolated Building using Shape Memory Alloy with Friction Pendulum System under Near-fault Excitations

Abstract

Structures close to causative earthquake faults may exhibit substantially different seismic responses than those recorded away from the excitation source. In the near-fault zone, long duration intense velocity pulses can induce unexpected seismic demands on isolated buildings. This study investigates the performance of a five-storey building frame isolated with a shape memory alloy based friction pendulum system (SMA-FPS) under near-fault excitations. The effectiveness of SMA-FPS is quantified by comparing the same isolated structure subjected to a friction pendulum system (FPS). Parametric studies, optimal analysis and numerical simulations are carried out on the structural parameters of the isolation systems. For this, the particle swarm optimization (PSO) method is used to acquire optimal characteristic strengths of SMA-FPS. The transformation strength of SMA and frictional coefficient are selected as two design variables to minimize the top storey acceleration, which is used as the objective function to optimize the seismic reduction efficiency of SMA-FPS system. The optimal seismic response of the structure isolated by SMA-FPS achieves superior performance over FPS under near-fault excitations. Moreover, the study reveals that the optimal SMA-FPS system significantly reduces the bearing displacement as compared to the FPS system. Finally, the computational results are validated with numerical simulation performed in SAP2000 which provides the consistent result.