Seismic vulnerability analysis of storage tanks for oil and gas industry

This paper aims to present an appropriate procedure for analytically deriving fragility curves of steel fuel storage tanks. At first, the analysis of critical damage states of steel storage tanks observed during past earthquakes is presented. Possible numerical models of tanks subjected to earthquakes are then discussed. An overview of seismic fragility methodologies for tanks is next presented. The attention is paid to an analytical method, i.e., cloud method, which is conducted by using a probabilistic seismic demand model and nonlinear time history analyses. A broad tank, which is located in a refinery of Italy, is considered for the fragility evaluation. Resulting fragility curves for critical damage states of the tank such as the plastic rotation of the shell-to-bottom plate joint, the buckling of the bottom shell course, and the material yielding of the shell plate show a high seismic vulnerability of the tank.