Seismic Fragility Estimates and Optimization of Retrofitting Strategies for Reinforced Concrete Bridges: Case Study of the Fabela Bridge in Toluca, Mexico

Seismic fragility estimates are computed for the Fabela Bridge, a five-span single-column bent reinforced concrete bridge, located in Toluca, Mexico based on previously developed probabilistic models for the capacity and demand of typical reinforced concrete bridges. The seismic fragility estimates are computed considering deformation failures in the columns. The approach used in this study properly accounts for epistemic and aleatory uncertainties of the problem. The properties of the bridge used to develop the fragility curves are estimated by matching the frequencies of a 3D finite element model to field data. For this purpose, a 3D finite element model of the studied bridge is created based on the available information of the bridge including drawings and field observations. Then the model is updated based on the modal frequencies obtained from measured accelerations in a series of forced vibration tests on the bridge. Fragility curves are generated to assess the seismic vulnerabilities of the current bridge. Different retrofit strategies are also applied to the bridge model to generate new fragility curves for a retrofitted bridge. The optimal retrofit strategies are determined based on the developed fragilities.