Seismic Safety of Ageing Infrastructure: The Role of Corrosion in Vulnerability Assessment of Reinforced Concrete Bridges

The aging of road infrastructure network, combined with the evolution of traffic loads and the tightening of regulatory requirements, demands a critical reassessment of structural safety, particularly with regard to seismic risk. Many existing bridges, designed according to outdated standards and without consideration for modern seismic criteria, are now required to meet performance levels that are significantly higher than originally intended. In this context, material degradation, especially steel bar corrosion in reinforced concrete, emerges as a critical factor that can significantly affect structural response. This study explores feasible strategies for integrating material deterioration into seismic vulnerability assessment of critical infrastructures through numerical modelling. To this end, an existing Italian reinforced concrete bridge with Gerber saddles was analysed as a representative case study. A corrosion evolution profile was developed to simulate realistic long-term deterioration. This approach allowed for the evaluation of the evolution of key structural parameters, including stiffness, strength, fundamental periods and energy dissipation capacity as well as the resulting reduction in the global safety factor, through linear and nonlinear dynamic analyses. The findings demonstrated that the progressive advancement of degradation can severely compromise seismic safety, highlighting the importance of explicitly incorporating such effects into structural assessment to enhance seismic risk management of ageing assets.