Earthquake Response of Isolated Elevated Liquid Storage Steel Tank

The seismic response of liquid storage steel tanks with the variable frequency pendulum isolator (VFPI) is compared with that of the same liquid storage steel tanks isolated using the linear elastomeric bearings under real earthquake ground motion. In order to measure the effectiveness of isolation system, the seismic response of isolated steel tanks is compared with that of the non-isolated steel tanks. Two types of isolated tank models are considered in which the bearings are placed at the base and top of the steel tower structure. The seismic response is obtained by the Newmark's step-by-step method. The response of two types of tanks, namely slender and broad tanks, is obtained and a parametric study is carried out to study the effects of important system parameters on the effectiveness of seismic isolation. The parametric study has been carried out to examine the behavior of liquid storage steel tanks isolated with VFPIs. The important parameters considered are the friction coefficient of the VFPI, the Frequency Variation Factor (FVF) and the tank aspect ratio. In less computational efforts the analysis of seismic response for elevated steel tanks is accurately obtained.