A study to investigate the response of ground supported base-isolated liquid storage tanks under recorded near-fault earthquakes as well as under equivalent acceleration pulses is presented herein. The liquid storage tank is modeled using mechanical analogue with three lumped masses, and lead-rubber bearing (N-Z type isolator) is considered as isolation system. The hysteretic behavior of the N-Z type isolator is modeled using Wen’s equation, and the equations of equilibrium for the overall dynamic system are solved by Newmark’s method. Three recorded near-fault earthquake acceleration time histories are used to find the response of base-isolated liquid storage tanks. The response under the equivalent pulses, proposed by several researchers to model near-fault recorded earthquake ground accelerations, is also examined. A parametric study, to evaluate the variation of important response quantities with change in the important system parameter, such as isolation time period, is also carried out. It is observed that equivalent acceleration pulses are quite effective to model the peak response of base-isolated liquid storage tanks under near-fault earthquakes. Nevertheless, the post-peak response time history may not be well captured by the equivalent acceleration pulses, specifically for broad tanks. Hence, the behavior of the tank is further examined under the residual motion. It is observed that residual motion affects the response time history after the peak, and this phenomenon is more prominent for broad configuration of tank.

Base Isolation, Earthquake; Near Fault; Pulse, Residual Motion,;Tank.