In recent years, the structural assessment of existing bridges and viaducts has become increasingly significant in the field of civil engineering. This is due to the fact that most of these structures have exceeded their design service life, and require retrofitting interventions and detailed analyses to evaluate their state of deterioration.

In this regard, in Italy, after the collapse of the Morandi Bridge in 2018, Guidelines for the classification and management of risk, safety assessment, and monitoring of existing bridges were issued aiming to standardize the methodology for analysing the safety of bridges according to a multi-level approach. Among the great variety of bridge classes existing at a national level, concrete bridges represent a remarkable percentage. Within this class, prestressed beams are the preferred option for a wide range of bridge spans and types. These elements represent the most stressed structural components under service loads and the most exposed elements to deterioration phenomena, hence the importance of adequately assessing their safety level to avoid important infrastructure network disruptions and long-term consequences.

The present work addresses this problem with reference to a real multi-span prestressed concrete bridge, numerically modelled under traffic and seismic loading conditions following the procedure proposed by the Italian Guidelines (MIT, 2020). Based on the obtained results, parametric analyses were conducted for various damage scenarios, considering progressive degradation phenomena due to corrosion. Various models proposed in the literature were employed for this purpose, incorporating the effects of reduced strength and ductility in concrete and steel. It was observed that the reinforcement corrosion in prestressed beams can lead to a reduction in strength up to 15-20% for high corrosion rates.