Seismic Behaviour of Fluid Storage Containers Considering the Effect of Soil and Earthquake Characteristics

Seismic analysis of storage containers is quite different from the analysis of general structures such as bridges or buildings. In the general structures, the interaction happens amongst solids only, but in tanks, the contact is between solid and liquid. Usually, a simplified model using the spring and mass system of the tank-fluid system is considered to analyse the storage containers, without including the interaction effect between the storage container wall and fluid. Also, the tank's base is idealized as fixed, even though the soil below the foundation has flexible behavior. For a realistic study of the behavior of the container supported on soil, it is essential to consider the interrelation between the tank and fluid at the fluid-wall interface, as well as the interaction between soil and container at the base. Therefore, the response of the container considering the influence of soil and fluid is investigated in the current study. The container-fluid-soil system is idealized using the Finite element method. The coupling effect between the container and fluid is modeled using the Pressure formulation approach. The container is subjected to six past earthquakes. The effect of ground motion characteristics and the influence of soil conditions are studied on the behavior of the container. Response parameters taken into account for the study are in terms of displacement at the container top, base shear, hydrodynamic pressure on the container wall, and sloshing. In order to investigate the interaction effects between the foundation and soil medium, soils with various flexibility parameters are considered. The study shows that the soil conditions, as well as earthquake characteristics significantly influence the response of the container in terms of displacement at the top, base shear, and hydrodynamic pressure. However, it is observed that the foundation-soil interaction modeling has very little impact on the sloshing displacement of the container.