On the nonlinear dynamic analysis of base-isolated three-dimensional rectangular thin-walled steel tanks equipped with vertical baffle

Abstract

This paper intends at numerically analyzing the simultaneous influences of base-isolator system and vertical baffle on the seismic performance of a three-dimensional (3D) rectangular liquid storage container, presuming irrotational, inviscid, and incompressible flows. A boundary element technique with meaningful computational efficiency is primarily formulated to treat the spectral problem of liquid motion using the zoning method including the velocity potentials alone of the half free-surface length, which is coupled with Finite elements for tank wall using equilibrium and compatibility conditions. In the soil/foundation component, the foundation is modeled by shell finite elements and the half-space soil medium is modeled employing the external boundary elements, which fulfill the radiation condition of homogeneous media. Eventually, above two parts are attached to equation for isolator motion in the time domain, to attain the total system's nonlinear seismic response. The validity and efficiency of the present coupled numerical method is confirmed against available theoretical solutions and numerical predictions, revealing a good agreement with benchmark results. The sensitivity of base forces, the maximum hydrodynamic pressure and liquid oscillation in relation to some system parameters involving the baffle height, the base-isolator stiffness and the soil properties have been highlighted.