Seismic Responses Analysis of Base-Isolated LNG Storage Tank

Abstract

In order to study seismic responses of the base-isolation system, a three-dimensional 160 thousand cubic meters finite element model of LNG storage tank is established by the general finite element code ABAQUS. Then, the nonlinear dynamic analyses are conducted on the base-isolation LNG storage tank. The liquid filling ratio and the earthquake motion periods have been taken into accounts for further investigating the efficiency of the isolation system. To accurately simulate the interaction between the inner steel tank and the outer concrete tank, a thermal insulation layer is also simulated in details. Meanwhile, the impulsive and convective hydrodynamic forces towards outer tank wall, which are induced by a horizontal earthquake motion, are considered through the additional mass method. The connection elements “cartesian” and “align” are combined to simulate isolators to achieve a reasonable and accurate analysis for the LNG storage tank. The numerical results show that the lead rubber bearings have excellent effectiveness in decreasing most seismic responses. This is more remarkable in the cases of larger volume of liquid and stronger earthquake motion. The efficiency of the isolation system is better in the earthquake ground motion with shorter predominant periods. Whereas, the impulsive effect of liquid mass is strengthened in earthquakes with long predominant periods and then to magnify the displacement of tank walls.