A Study on Restoration Mechanism in Rocking Behavior of Flat-Bottom Cylindrical Storage Tank During Earthquake

Abstract

In this study, based on the results of FEM dynamic analysis, the restoration mechanism for the tank rocking motion is discussed by comparing the overturning moment calculated by the Housner’s theory and the restoring moment which is composed of the distribution of the uplift force and the weight of the tank shell. The comparison implies that the restoring moment which is composed of the distribution of the uplifting force and the weight of the tank shell is unlikely to be a function as a restoration mechanism against the overturning moment during the tank rocking motion. Furthermore, the rocking angular acceleration obtained from the equation of motion considering the effective moment of inertia of the content liquid and the results of the FEM dynamic analysis are compared. From the comparison, this study concludes that the rotational equilibrium equation for the tank rocking motion should be formulated as an equation of motion that takes into account the effective moment of inertia of the content liquid.