Seismic vulnerability assessment of existing RC bridges

The importance of managing and monitoring the network of roads and bridges is a very crucial issue in Italy for many reasons. First of all, Italy has a complicated orography and is interested by seismic and/or hydrogeological hazards. Then, degradation and obsolescence phenomena are frequent on infrastructures approaching the end of their nominal life. In 2020, the Italian Ministry of Infrastructure and Transport (MIT) published the Guidelines for risk classification and management, safety assessment, and monitoring of existing bridges, as an attempt to unify the multiple procedures of inspection, monitoring, and maintenance of infrastructures. An important stage of the risk classification regards the seismic vulnerability characterization of reinforced concrete and prestressed reinforced concrete bridges. In this work, the most important parameters for the seismic vulnerability definition of such bridges are identified. Fragility curves for the different combinations of these parameters have been developed to define macro-classes of vulnerability. These combinations are based on parameter distributions specifically calibrated for the Italian bridges. The fragility curves are developed by adopting a capacity assessment through inelastic pushover analysis and considering the critical components among the ones included in the bridge model. In particular, specific focus is done with respect to the height of the piers and the boundary condition at deck ends. For each of these parameters, the fragility curves trends, related to extensive damage in the bridges, are proposed to show the influence of pier height and boundary condition on the seismic vulnerability of the bridges.