Procedure for Seismic Analysis of Liquid Storage Tanks Using FEM Approach and Analytical Models

Liquid storage tanks are important components of liquid transmission and distribution systems and therefore should be properly designed to withstand various loadings. One of which is seismic excitation. The paper deals with the seismic analysis of the flexible circular vertical ground-supported liquid storage tank with the aim to determine the dynamic properties (e.g. natural frequencies and their respective mode shapes of the tank and the liquid) and the seismic characteristics (e.g. hydrodynamic pressure distribution, base shear, overturning moment and maximum wave height). During seismic activity, a specific interaction occurs between the tank and the liquid. It is expressed as a vibration of the tank and contained liquid. One (lower) part of liquid moves in unison with the structure, the second (upper) part representing the free surface tends to experience a sloshing effect. The paper is also dedicated to comparing the acquired results from the seismic analysis computed by FE method (ANSYS) with methods using analytical models (spring-mass and pendulum) and Eurocode 8, respectively.