An analytical method is proposed to determine the dynamic response of 3-D rectangular fluid containers with four flexible walls, subjected to seismic ground motion. By applying Rayleigh-Ritz method using the vibration modes of flexible plates, fluid-structure interaction effects on the dynamic responses of fluid containers are considered. A mechanical model, which takes into account the deformability of the tank wall, is developed. The maximum seismic loading of the base at the tank and a section immediately above it can be predicted by this model. Accordingly, a 2-D simplified model is proposed to evaluate pressure distribution on the flexible tank wall. The effects of base-isolation on the seismic response of rectangular liquid storage tanks subjected to horizontal seismic ground motion are presented.
