Seismic control of concrete rectangular tanks subjected to bi-directional excitation using base isolation, considering fluid-structure-soil interaction

In the current paper, the various responses of concrete rectangular liquid storage containers under seismic load, each isolated by a lead- rubber bearing subjected to bi-directional- directional earthquake forces are investigated. A parametric study is conducted to investigate the effects of isolation period, yield strength of the isolator and the effects of soil- foundation interaction for non- isolated and base- isolated tanks located on different soil types. In most cases, the value of base shear, base moment, wall displacement and hydrodynamic pressure is reduced by the effect of the isolators whose effective frequency is within the appropriate range. The sloshing displacement is amplified due to seismic isolation of the tanks for both tall and shallow tank configurations. Also, it is found that the seismic isolation technique is more efficient for the more flexible tank. Studying various soil types indicates that, unlike the responses of non- isolated tanks which change drastically for different soil types, the responses of base- isolated structures are less affected. Finally, it is observed that the variation in structural responses is not only related to the superstructure configuration and bearings properties but also depends on the earthquake specifications.