Many liquid storage tanks around the world have affected by earthquakes. This structure can store dangerous chemical liquids. Hence dynamic behavior of ground supported rectangular storage tanks is very important due to their applications in industrial facilities. In current research, the seismic behavior of two water storage rectangular concrete tanks is examined. For this purpose, these tanks are modeled in FEM software for analyzing. These tanks are analyzed under four type of analysis: static, modal, response-spectrum and time-history analysis. Time history analysis can take all the nonlinear factors into the analysis, so it is used to estimate the exact amount of structural response. In time history analysis, earthquake accelerogramsof Tabas, Kobe and Cape Mendocino have been applied to tanks. Finally, it is resulted that Displacement, base shear and wave height obtained from time history analysis are more than those of response spectrum analysis, indicating insufficiency of response spectrum analysis. In time history analysis, the maximum displacement is achieved in highest part of the tanks. It is due to the wave height which created in earthquake. By increasing in dimension, the wave height is also increased. پرونده مقاله