Seismic Response Analysis of Rectangular Reinforced Concrete Tank Constructed on Loess Soil

Liquid storage tanks are an essential container structure widely used in various industries. In earthquake disasters, liquid storage tanks cause not only direct disasters but also induce secondary severe disasters, such as fires, explosions, nuclear leaks, and human and animal poisoning. The latest research on seismic analysis of structures showed that soils with different stiffness can affect the seismic response characteristics of surface structures, and various irregular topographies can also alter the degree of seismic-induced damage to surface structures. Studying the seismic response of liquid storage tanks can mitigate the risk of earthquake damage to these vital structures.

This study used finite element simulations. Three sizes of liquid storage tanks with different aspect ratios were selected, including the squat, square, and slender tanks. Three conditions were considered for the tanks' liquid: empty, half-filled, and fully filled. Two types of topographies were considered, including flat and step-like slope topography with an inclination angle of 116.6°. Nine natural earthquake records were used for seismic analysis and divided into three categories: high-frequency, medium-frequency, and low-frequency. Established finite element models were validated through comparison with the results of other studies. The dynamic time history analysis was carried out for each finite element model. The tank's base shear forces, the normal stress in the tank wall, the shear stress in the tank bottom, and the maximum displacement of the tank wall were measured and compared.

The step-like slope topography and loess soil significantly amplified the seismic response of the liquid storage tank. Moreover, as the liquid height and the tanks’ aspect ratio increased, the seismic damage intensity also increased. The seismic response of the liquid storage tank was generally more sensitive to low-frequency and medium-frequency seismic records. The Eurocode 8’s equation underestimated tanks’ base shear when located on a step-like slope topography.

The obtained results demonstrated the significant effect of irregular topography and loess soil on the seismic response of liquid storage tanks. Therefore, it was concluded that they should be considered when liquid storage tanks are designed for seismic actions.