Fragility curves of typical as-built highway bridges in eastern Canada

The bridge network in the Province of Quebec in Canada consists of a total of 2672 multiple-span bridges. Due to earlier design practices, many bridges in this region lack seismic detailing and may be vulnerable to future earthquake events. Probabilistic models of the anticipated seismic performance of these bridges are lacking, however, as is an understanding of the relative vulnerability of the different classes of bridges common in the region. To support future seismic-risk mitigation efforts, this paper assesses the seismic vulnerability of bridge classes typical to Quebec through the development of bridge fragility curves. Bridge classes are defined for fragility modeling according to the bridge superstructure material and construction type to efficiently quantify their vulnerability. The analytical fragility approach conducted uses three-dimensional nonlinear finite element models for each bridge class, representative of typical geometries and design details as well as ground motions representative of eastern Canada. Bridge-system fragility curves are developed considering the vulnerability of critical components to assess the probability of bridge damage given a ground motion intensity measure, adopted as peak ground acceleration. The results indicate that the component governing the fragility of the bridge system varies depending on bridge class and limit state. Concrete-girder bridges are found to be more vulnerable than steel-girder bridges, and continuous-span bridges are more vulnerable than the simply supported span bridges. The resulting fragility curves can be used in Quebec to enable regional risk assessment, prioritization of bridge retrofit, or deployment of inspection crews after a seismic event.