Evolution of the seismic performance of existing reinforced concrete motorway bridges under different corrosion scenarios

Over the last few decades, the collapse of several existing RC bridges has drawn attention to the durability of these strategic infrastructures. In fact, one of the most important factors influencing the load-bearing capacity of existing RC structures is the corrosion of the steel reinforcement due to the carbonation phenomenon. Focusing on the Italian motorway network, most of the motorway bridges were built around the 1960s, so scheduling maintenance interventions is fundamental to guarantee an adequate safety level. This paper investigates the evolution of the seismic behaviour of existing reinforced concrete (RC) bridges under different corrosion scenarios of steel reinforcement of the piers. In particular, three corrosion scenarios are considered: slight, moderate and high. The effects of this phenomenon on structures with a lifetime of 75 years are analysed. Appropriate risk indices were calculated by means of the execution of non-linear analyses in order to define the seismic performance evolution of the analysed structure.