Vulnerability of bridges exposed to coastal hazards and climate change

Many bridges in the United States (US) are located in areas prone to storm surge and sea level rise. Past events have highlighted the structural vulnerability of these structures when subjected to hurricanes, triggering the development of fragility models for bridges subjected to hurricane-induced surge and waves. However, parameterized fragility models are lacking for a range of different bridge configurations to enable rapid application across a region and/or to explore climate change effects on bridge damage risks. In addition, fragility models assuming the same superstructure across a bridge for developing fragility curves may not provide full information on vulnerability given that different types of superstructures may exist within a single bridge. Thus, this study assesses the fragility of individual spans for different bridge classes subjected to storm surge and waves. The bridge deck is modeled as a grillage and wave force time-history analysis is conducted on bridge models from each class generated through Latin hypercube sampling. Logistic regression is applied to derive parameterized fragilities given hurricane intensity measures. This paper then incorporates the new models in a case study along the Houston-Galveston region of Texas for storm scenarios with and without sea level rise. The results show the variation in failure probability across different bridge classes and the dependence of these differences on the intensity of the hazard. In addition, the results reveal the anticipated increase in failure probability that may be expected with alternative climate change scenarios in which sea level rise is incorporated in the hurricane hazard model used for the scenario risk assessment.