Seismic Analysis of Oil Storage Tank

Liquid containing tanks (LCTs) are used in water distribution systems and in the industry for storing water, toxic and flammable liquids and are expected to be functional after severe earthquakes. Seismic analysis is performed on numerical model of steel circular vertical ground-situated model tank containing oil. Tanks are assumed to be fixed to a rigid foundation. The responses of cylindrical steel tank are analyzed using Time History Analysis and Modal analysis by means of finite element software package ANSYS. Variation in mode shapes with changing height of liquid fill is observed. A parametric study is conducted by varying the liquid fill height and hence the variations of maximum sloshing wave height, equivalent stress, normal stress, natural frequencies and mode shapes are determined. And it is found that sloshing height increases with increase in liquid height. It also shows that increase in volume of stored liquid leads to a rise in chances of Elephant-foot buckling. However, the diamond wall buckling occurs in all fill condition as the thickness of the shell wall is small.