Seismic Analysis of Conventional and Isolated LNG Tanks Using Mechanical Analogs

The seismic response of a conventional and an isolated vertical, cylindrical, Liquefied Natural Gas (LNG) tank is computed using a mechanical analog and a finite element code to judge the utility of the analog for preliminary design and of the effectiveness of seismic isolation. Data reported and statistically sorted include base shear, global overturning moment, and wave height in the tank. The results obtained from the two numerical models are in good agreement and demonstrate that the mechanical analog can be used with confidence for the preliminary analysis and design of conventional and isolated LNG tanks that have similar dimensions to the sample tank of this study. The base shear and overturning moment in the seismically isolated LNG tank are 10% to 15% of the values computed for the conventional tank; the wave heights are unaffected by the introduction of a seismic isolation system.