Fluid-structure interaction problems: An application to anchored and unanchored steel storage tanks subjected to seismic loadings

Abstract: The estimation of the degree of risk of steel storage tanks from an industrial or nuclear power plant during an earthquake event is a very difficult task since the dynamic behaviour of the tank-liquid system is highly complex. The seismic response of steel storage tanks is quite different from building structures not only due to hydrodynamic effects acting on the shell and bottom plate but also because of many sources of nonlinear behaviour mechanisms. For the earthquake-resistant design of tanks, it is important to use a rational and reliable nonlinear dynamic analysis procedure, which is capable of capturing the seismic behaviour of the tanks under artificial or real earthquakes. The present paper deals with the nonlinear finite element modelling of steel storage tanks subjected to seismic loadings. The interaction effects of fluid and structure are modelled using a surface-based acoustic-structural interaction in the ABAQUS software. The successive contact and separation between the bottom plate and its rigid foundation caused by sliding and uplift are taken into account by a contact modelling approach. Reduced scales of both slender and broad cylindrical steel storage tanks from a shaking table campaign within the framework of the INDUSE-2-SAFETY project are selected for the study. The seismic responses of the tanks including the hydrodynamic pressure distribution acting on the shell plate, the elevation of the liquid free surface, and the uplift response of the bottom plate when the tank is unanchored are presented and compared with the experimental results. The responses obtained from the refined models are also compared with those obtained using a simplified approach, which is based on the lumped mass model of the liquid motion.