Sliding System For Isolation of Liquid Storage Tanks

Abstract

Response of ground supported liquid storage tanks isolated by the friction pendulum system, FPS, is investigated under two horizontal components of real earthquake ground motion. The continuous liquid mass is lumped as sloshing mass, impulsive mass and rigid mass and the corresponding stiffness associated with these lumped masses is worked out depending upon the properties of the tank wall and liquid mass. The governing equations of motion of the tank with the FPS are derived and solved by incremental step-by-step method with iterations. The frictional forces mobilized at the interface of the sliding system are assumed to be velocity dependent and their interaction in two horizontal directions is duly considered. A parametric study is conducted to study the effects of important system parameters on the effectiveness of seismic isolation of the liquid storage tanks. The various parameters considered are the aspect ratio of the tank and isolation period and friction coefficient of the FPS. It has been found that the FPS is quite effective in reducing the earthquake-induced forces of liquid storage tanks and its effectiveness is influenced by the above system parameters.