Rocking Response Analysis of Flat-Bottom Cylindrical Tanks Considering Rotational Inertia of Content Liquid

Abstract This paper proposes an analytical method for calculating rocking responses of unanchored tanks during seismic ground motion. Some researchers have proposed the analytical methods to calculate seismic responses of unanchored tanks without considering the rotational inertia of content liquid. In other words, most of method for a time-history analysis of tank rocking responses are assumed that an equilibrium equation in direction of rotation can be formulated as a static equilibrium equation in which the overturning moment and the restoring moment are equal. Even a model that considers rotational inertia of content liquid was proposed in the past, the definition of moment of inertia is ambiguous. On the other hand, there a study that derives moment of inertia from a physical background and alleges the importance of the moment of inertia in the tank rocking response. In this study, an analytical method of a time history analysis of tank rocking motion considering the rotational inertia of content liquid is proposed. Furthermore, results of the proposed method are compared with results of the FEM dynamic analysis to validate the accuracy of the proposed method. Finally, comparisons with results of the conventional calculation method are also conducted.