DIRECTIONAL-DEFORMATION ANALYSIS OF CYLINDRICAL STEEL WATER TANKS SUBJECTED TO EL-CENTRO EARTHQUAKE LOADING

Abstract

Cylindrical steel storage tanks are widely used for the storage of various liquids, industrial chemicals and firefighting waters. They have been used for cooling purposes in nuclear power plants in recent years. Liquid-storage tanks have many different configurations; however, in this study, cylindrical ground-supported liquid steel tanks were preferred due to their simplicity design and performance of resistances against seismic loads, when compared with other configurations. Earthquakes are a natural occurrence and are unpredictable and complex; thus, the steel storage liquid tanks are expected to withstand earthquake-related loads. These tanks may be exposed to some damages such as elephant-foot buckling, diamond-shape buckling, overturning and uplifting during earthquakes. They can also cause great financial and environmental damage with their hazardous chemical contents. Dimensions of cylindrical open-top, flat-closed and torispherical-closed-top tanks were determined for 3D-finite element method (FEM) models in an ANSYS workbench software. This article focuses on the seismic-activity-resistant ground-supported cylindrical (vertical) steel storage liquid tanks. Seismic analyses were conducted under El-Centro earthquake loads. Directional deformation, equivalent stress and acceleration results were presented for both impulsive and convective regions. In this study, directional deformations of the tanks with the same diameter and three different roofs (open-top, flat-closed and torispherical-closed) were compared after the seismic analysis. The results show that if the cylindrical steel water tank roof is closed in a torispherical dome shaped, the directional deformation will decrease. Hence, torispherial roof shape of tank is recommended.