Seismic Safety Analysis of Double-Steel-Wall Full-Containment Liquefied Natural Gas Storage Tanks Under Service and Leakage Conditions

Abstract The seismic resilience of liquefied natural gas (LNG) storage tanks is critical for public safety and economic stability. This study accesses the safety of a 30,000 m3 double-steel-wall full-containment LNG storage tank under seismic and leakage conditions, employing the two-way fluid–structure interaction and added mass methods to analyze the seismic time history response and evaluate the tank's seismic load resistance throughout its lifespan. The results showed that sloshing height, stress, and displacement responses of the storage tank remained within safe limits under seismic loading. The fluid's impact on the inner tank wall was most significant at the bottom, where axial stress increased the most. Under the combined effects of leakage and aftershock, hydrodynamic pressure notably affected the middle and lower sections of the outer tank wall, increasing the displacement gradient along the tank's height and raising the risk of elephant's foot buckling at around 1/10 of the wall height. After leakage from the inner tank, hydrostatic pressure from the leaking liquid caused a substantial increase in stress, especially in the circumferential direction.