Seismic Response of Base Isolated Liquid Storage Tanks under Near Fault Ground Motions

Among the different base isolation systems, the Friction Pendulum System (FPS), whose period does not depend on the weight of the structure, are more appropriate for the isolation of liquid storage tanks. In this paper, the seismic behavior of the cylindrical liquid storage tanks base isolated by FPS is investigated under near-fault ground motions. Such earthquake ground motions have long-period components that may affect the long-period sloshing motion of the liquid. For the required analyses, the isolated tank-liquid system is modeled as three lumped masses known as convective mass, impulsive mass and base mass. The interaction between the fluid and the structure has been taken into account by connecting the liquid masses to the tank wall with specific springs and dampers. Nonlinear time history analyses are carried out to investigate the effects of the isolation period. The results obtained indicate that the friction pendulum system reduces the response parameters of the base isolated tank in comparison with the fixed-base tank