Modeling the impact of corrosion on seismic performance of multi-span simply-supported bridges

The corrosion of steel rebar negatively affects the serviceability and capacity of RC bridges and increases their vulnerability in earthquakes. Most of existing numerical models rely on either solid elements with a detailed corrosion damage model, involving impractical computational costs, or fiber beam elements with an incomplete corrosion damage model, requiring careful justification. A time-dependent corrosion damage model based on fiber beam elements was herein proposed as a numerical tool conserving both computational efficiency and appropriate accuracy. The proposed corrosion damage model comprehensively incorporates most of the potential corrosion-induced damage patterns on reinforced concrete, including cross-section loss, ductility degradation and compressional buckling of rebar; deterioration of cover concrete and core concrete; and deteriorated strain penetration effect. This corrosion damage model was implemented in OpenSees via fiber beam elements in which the strain penetration effect was simulated by the Bond_SP01 material with the Zero Length element. The accuracy of corrosion damage model was validated with existing experimental data of cyclic loading tests on corroded RC columns. A multi-span simply supported (MSSS) bridge was selected to showcase how to implement the proposed corrosion damage model in the time-dependent seismic fragility analysis of RC bridges. A sensitivity analysis was conducted to illustrate the roles of different corrosion damage patterns in altering seismic fragility of RC bridges. It revealed that the corrosion-induced deterioration of strain penetration and rebar yield strength significantly increase the seismic fragility of the corroded MSSS bridge.