Study on the dynamic behavior of cylindrical steel liquid storage tanks using finite element method

Abstract

Dynamic behavior of ground supported cylindrical storage tanks (CST) is of crucial importance because of its applications in industrial complexes. Seismic behavior of tanks is greatly affected by the height to diameter ratio, fluid height and fluid type. Five CSTs with different height to diameter ratios, three CSTs with the same height and diameters but various fluid heights and one CST with two different fluid types are selected to determine the effect of height to diameter ratio, fluid heights, and fluid type on the seismic behavior of the tanks respectively. Static, modal, response spectrum, and time history analyses are used in this study for the selected CSTs using ANSYS finite element software. In the time history analysis method, the Tabas, Kobe and Cape Mendocino earthquake records have been utilized on the first five CSTs to ascertain the effect of height to diameter ratio and the Tabas earthquake record is used for the rest of CSTs. Results show that an increase in fluid height lead to a corresponding increase in the base shear. Based on observations, 100 percent increase in the diameter showed 63 percent increase in sloshing under the response spectrum and 70 percent under time history analyses. Based on static and response spectrum analyses, the highest values of displacements are obtained at the lowest part of the tanks, while in time history analysis, the highest is obtained at the top of the tanks. All analyses showed that the maximum stress occurred at the height of 1 to 2 meter from the bottom of the tanks.