Seismic performance of deteriorating concrete bridges

This study examines the effect of corrosion on reinforced concrete structural elements of a bridge overpass in seismic affected areas. Starting from a literature review to identify the existing deteriorating models, a case study is selected to perform seismic analyses. It allows to assess the structural response at different levels of reinforced concrete degradation due to corrosion. The selected case study is a frequently used structural system with several existing examples in critical infrastructures all around the world. Consequently, an in-depth analysis of the degradation of this type of system, with the identification of the most appropriate time for restoration and the possible retrofitting strategies may be of interest. The bridge is assumed to be located in Sicily, the largest island in Southern Italy. In particular, a site close to the Strait of Messina has been selected with a high seismic hazard. According to the current Italian standard for constructions, it belongs to the first seismic category among four. Indeed, a strong earthquake destroyed all the city in 1908. A finite element model of the bridge overpass is prepared to perform the seismic analyses. Different levels of degradation have been simulated by using a deterministic approach. They include the reduction of the steel reinforcement areas, the bond decreasing and the steel strength losses due to corrosion. The position of the bridge concerning the sea is also considered because it can also affect the steel reinforcement degradation due to pitting corrosion. Finally, retrofitting strategies to improve the seismic performance of the bridge are evaluated to preserve it from demolishing and rebuilding.