EVALUATION OF MAINTENANCES INTERVENTION PERIOD ON STOCK OF EXISTING RC BRIDGES SUBJECT TO DAMAGE PHENOMENA

During last decades, the attention of the scientific community on the evaluation of the load-bearing capacity of existing reinforce concrete (RC) bridges has significantly increased even as a result of the recent collapses which have occurred. Particular attention is focused on the seismic performance of the existing RC bridges especially if located in areas characterized by high seismicity level such as Italy. One of the most important problems that affects the seismic performance of this structures is the presence of corrosion effects due to carbonation phenomenon which may involve the steel reinforcements of the piers. In this paper the evaluation of the seismic vulnerability of an existing RC bridge located in Italy and built around the 1960’s is presented, considering three different corrosion scenarios (slightly, moderate, and high). Non-linear time history analysis has been performed considering a simplified Finite Element Model (FEM) where the structural elements have been imple-mented with beam elements and the non-linear behavior of the piers has been introduced using appropriate concentrated plastic hinges. The carbonation effects have been modelled considering the piers steel reinforcement area reduction as a function of the age of the bridge. Risk indices evaluated as the ratio of the peak ground acceleration leading to collapse of the first structural element and the design peak ground acceleration, are calculated to define the seismic vulnerability of the analyzed structure.