Seismic Fragility of a Highway Bridge in Quebec

Abstract

The seismic vulnerability of the Chemin des Dalles Bridge over Highway 55 located in Trois-Rivières (Quebec, Canada) was evaluated through fragility analysis using field- and laboratory-validated models. This approach offers an effective means to capture the uncertainties in ground-motion realizations, the demands placed on key structural components, and the capacity of the components to resist various levels of seismic excitation. A series of 180 synthetic ground-motion time histories (GMTHs) compatible with eastern Canada was used to capture the uncertainties related to the hazard. Nonlinear time history analyses were performed with these GMTHs and statistically analyzed to define the probabilistic seismic demand model for the abutments, bearings, and columns, which are the critical components. Data from the literature, coupled with sectional and damage mechanics analyses, were used to define the limit states (LSs) for these components. Bridge component and system fragility curves were used to evaluate the likely failure modes of the bridge and potential targets for retrofit, while accounting for key sources of uncertainty in the performance assessment. The results reveal the seismic vulnerability of this specific bridge and even offer insight into the seismic vulnerability of a typical multispan girder-type concrete bridge in Quebec.