Seismic analysis of a soil-liquid tank system using the two-step method

Seismic analysis of soil-structure interaction (SSI) is a challenge due to the non-linearities of soil-foundation interaction (SFI). The reliability of the design and the analysis results will suffer if SSI is ignored. In this paper, a two-step method based on the superposition theorem is used to perform a seismic analysis of a soil-foundation-tank-liquid system (soil-liquid tank system). The SFI analysis was conducted in the first step using the CyclicTP program's finite-element method. Meanwhile, the liquid tank system was analyzed in the second step using the lumped-parameter method. Numerical simulations conducted in homogeneous strata of sand soil demonstrated that the responses of the liquid tank were 24–70% higher than the results of the fixed-base model. Compared to the sway-rocking model, these responses did not differ by 20%. This study also investigated cohesive soils of homogeneous clays and multiple strata. The paper recommends that future research investigate the experimentation, the geometric nonlinearity of the soil-foundation system, and the stress-strain analysis of the tank wall