Dynamic Characteristics of Seismically Isolated Rectangular Tank–Liquid–Block Systems Implementing Lead Rubber Bearing Isolator

Abstract

This study comprehensively investigates the seismic response of a partially filled rectangular liquid tank equipped with a bottom-mounted submerged block under six real earthquakes of varying frequency contents. Based on a velocity potential theory, Galerkin’s method is employed for the liquid domain formulation. A finite element algorithm is developed for the model and the simulated results are validated with the existing solutions. A parametric study is conducted to present the influence of isolator properties on the critical seismic responses. The efficacy of lead rubber bearing is emphasized in the overall dynamic response of the tank–block–isolation systems by varying the location and height of the block. The total and impulsive hydrodynamic pressure of the non-isolated tank decreases when a block is mounted at the base and a subsequent reduction is noticed due to the eccentricity of the block across the tank wall close to the block. Also, the eccentric configuration of the block has shown a typical reduction in the total base shear for most of the earthquake responses when a specific block depth is considered. Furthermore, a significant decrease is noticed in the impulsive and total hydrodynamic pressure and base shear due to the application of lead rubber bearing where the reduction is higher for high-frequency motions and relatively lower for low- and intermediate-frequency content seismic motions. The impulsive response is invariably dominant over the convective one in the overall dynamic responses of different non-isolated tank systems irrespective of the earthquakes whereas the convective response is found to be predominant in the base-isolated tank responses in majority of the earthquakes considered. However, the earthquake’s frequency has noticeably influenced the slosh elevation, total base shear and convective base shear responses.