Sh. Hashemi - PhD student, Department of Civil Engineering, Isfahan University of Technology, Iran
M. M. Saadatpour - Professor, Department of Civil Engineering, Isfahan University of Technology, Iran
R. Kianoush - Professor, Department of Civil

Seismic response analysis of partially filled flexible rectangular liquid storage tanks subjected to horizontal ground motion is presented in this paper. The coupling between liquid sloshing modes and wall vibrational modes is weak; consequently, for the analysis it is appriate to consider the two uncoupled systems separately. This includes the liquid wall system and the free surface gravity waves, in a similar rigid tank. Fluid-structure interaction effects on the dynamic responses of partially filled fluid containers,incorporating wall flexibility, are accounted for in evaluating impulsive pressure. The velocity potential in which boundary conditions are satisfied is solved by the method of separation of variables using the superposition principle. Based on the achieved solution, the impulsive pressure distribution is computed Solutions based on three-dimensional modeling of the rectangular containers are obtained by applying the Rayleigh-Ritz method using the vibration modes of flexible plates with suitable boundary conditions. Trigonometrical functions that satisfy boundary conditions of the storage tank such that the flexibility of the wall is thoroughly considered are used to define the admissible vibration modes. The analysis is thenperformed in the time domain. The influence of tank flexibility on the convective response components is generally small and may be neglected. Therefore, an analytic procedure is developed for deriving a simple formula that evaluates convective pressure and surface displacements in a simiar rigid tank. The results of this study are compared with previous published results. The variation of dynamic response characteristics with respect to different parameters involved of the tank is investigated

rectangular tank, dynamic analysis fluid-structure interaction, Rayleigh-Ritz