Fragility and risk assessment of aboveground storage tanks subjected to concurrent surge, wave, and wind loads

Comprehensive tools to assess the performance of aboveground storage tanks (ASTs) under multi-hazard storm conditions are currently lacking, despite the severe damage suffered by ASTs in past storms resulting in the release of hazardous substances. This paper presents a rigorous yet efficient methodology to develop fragility models and perform risk assessments of ASTs subjected to combined surge, wave, and wind loads. Parametrized fragility models are derived for buckling and dislocation from the ground. The buckling strength of ASTs is assessed using finite element analysis, while the stability against dislocation is evaluated using analytical limit state functions with surrogate modeling-based load models. Scenario and probabilistic risk assessments are then performed for a case study region by convolving the fragility models with hazard models. Results demonstrate that the derived fragility models are efficient tools to evaluate the performance of ASTs in industrial regions. Insights obtained from the fragility and risk assessments reveal that neglecting the multi-hazard nature of storms, as existing studies have done, can lead to a significant underestimation of vulnerability and risks. This paper also highlights how using surrogate model techniques can facilitate and reduce the computational complexity of fragility and risk assessments, particularly in multi-hazard settings.