Numerical Investigation of Fluid–Structure Interaction in LNG Storage Tanks under Seismic Loading

The seismic safety of liquid-filled cylindrical storage tanks is vital for the energy infrastructure, particularly in high seismic zones. This study presents a high-fidelity finite element analysis (FEA) of LNG storage tank system, comprising an inner steel tank and outer reinforced concrete tank. Given the complex nature of fluid-structure interaction (FSI) and the risk of sloshing -induced instability during seismic events, the objective is to provide a comprehensive numerical framework to assess the structural response unde r realistic earthquake loading condi tions. The Arbitrary Lagrangian -Eulerian (ALE) approach is employed to capture the dynamic interaction between the tank structure and the contained fluid, allowing for accurate simulation of sloshing behavior and hydrodynamic pr essures. For simplicity, water is used as the infilled liquid. The Concrete Damage Plasticity (CDP) model is adopted for the concrete components to account for nonlinear material degradation under seismic loading. Although the LNG storage system modeled in this study consists of outer reinforced concrete containment, the analysis primarily focuses on the inner tank's seismic response and associated fluid -structure interaction (FSI). The simulation results reveal that while the inner steel tank maintains stable performance under static conditions, dynamic loading produces transient stresses, localized deformation, and significant sloshing wave heights. given that the dynamic loading did not result in significant damage in compression and cracks in tension in the outer tank, detailed discussion on its behavior was omitted to maintain clarity and focus on the more critical inner steel containment. These findings emphasize the critical role of FSI in amplifying structural demands and demonstrate the need to go beyond conventional static or simplified dynamic