Study on the Predictive Evaluation Method of Load Acting on Roof in Nonlinear Sloshing of Cylindrical Tank

Sloshing is a motion of free liquid surface in a tank, which is caused by strong seismic waves with long period components. Sloshing with large amplitude causes damage to the tank roof. In our previous study, a method was proposed to evaluate vertical load acting on a roof of cylindrical tank due to collision of sloshing liquid surface. The method is a combination of the pressure model based on Wagner’s model and the simplified nonlinear sloshing model that calculates liquid surface shape and velocity. But, the method tends to underestimate the vertical load when roof height is high and overestimate when it is low. In this study, a new method is proposed to evaluate vertical load acting on a roof of cylindrical tank. This proposed method is constructed by a new pressure model, a new nonlinear sloshing liquid surface model, and a new local liquid surface wave model. Its pressure model is developed by applying the pressure model of two-dimensional flat plate surface to the circumferential wetted region of the roof. Its nonlinear sloshing liquid surface model is developed by adding higher order radial modes of liquid surface shape. Its local liquid surface wave model is developed by considering a nonlinear local liquid surface behavior induced by roof collision.