A Study of Dynamic Response Behavior During Earthquake for Large LNG Storage Tanks in Consideration of Uplift

Under severe seismic design conditions for LNG storage tanks in recent years, detail verification of soundness of structure including uplift behavior of bottom plate has been required. The design state is used to be analyzed statically as if the maximum dynamic pressure represents reciprocal processes during the earthquake. However, the previous studies reveals that the static analysis fails to calculate dynamic response behavior including uplift of bottom plate. In this paper, fluid-structure coupled 3-dimensional time-history FE analysis was performed for study of dynamic response including uplift of bottom plate. The time history FE analysis reveals undulating deformation at top of sidewall, which had not been observed under static conditions. This deformation is affected by stiffness of stiffener rings installed at the sidewall and effect of that on tank response was investigated. The FE analysis also proves that uplift height of bottom plate under reciprocal pressure is significantly smaller than that due to static conditions. This study makes clear the dynamical behavior of tank during earthquake and magnitude of influence of dynamic loading on that. In addition, the concept of introducing such dynamic effect to static analysis is proposed.