On the Seismic Behavior of Unanchored Liquid Containers

Abstract

This work presents a combined analytical/numerical methodology, predicting the behaviorof unanchored liquid storage tanks subjected to seismic excitation. First, the dynamic response of the system and the resulting hydrodynamic loads are determined by employing a simplified dynamic model. According to this model, the base uplift of the container isrepresented by an equivalent nonlinear rotational spring, placed between the foundation and the base plate of the tank. The characteristics of this spring are determined from static considerations, by applying standard finite element methodologies. Taking into account the form of the uplift spring stiffness, comprehensive parametric studies on the dynamics of unanchored liquid containers are first performed, in a systematic way. The results of these studies provide valuable insight into the role of the system parameters on its response. Once the dynamic loads are determined, a stress and buckling analysis can be performed, by employing finite element modeling again. The validity of the findings of the present work is checked through comparisons with experimental results.