Fragility assessment of above ground petroleum storage tanks under storm surge Kameshwar, Sabarethinam; Padgett, Jamie E.
Catastrophic failure of above ground storage tanks (ASTs) was observed due to storm surge during past hurricanes such as Katrina, Ike and Gustav causing severe environmental and economic impact. This paper evaluates the fragility of ASTs subject to hurricane storm surge to offer a basis for risk assessment of coastal facilities that store hazardous materials such as petroleum. Tank failures related to hurricane wind and earthquakes have been studied in literature; however, the effects of hurricane surge have not been addressed. Therefore, as a first step towards evaluating the fragility of ASTs under storm surge, this study identifies the primary modes of failure caused by storm surge—flotation and buckling. Next, uncertainties associated with each mode of failure are identified and characterized. The prime source of uncertainty considered for non-linear buckling analysis is geometric imperfections on the tank shell. Finally, these uncertainties are included while simulating response of ASTs during surge events. The results of these simulations are used to develop parameterized fragility curves using logistic regression. This methodology is applied to a typical tank from the Houston Ship Channel to assess conditional failure probability under storm surge. Key insights on dominance of the two modes of failure at different surge levels are also obtained. Using these observations, this study suggests structural and non-structural measures to prevent failure of tanks in future hurricane events. In addition, this paper provides a basis for parameterized fragility modeling of ASTs subject to hurricane storm surge that can be further extended to include other threats such as wave impact.
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