Time-dependent load-bearing capacity of corroded post-tensioned bridge beams with dapped-ends

Italian transportation networks include several existing bridges, built since the early ‘60s, usually character-ized by simply supported prestressed concrete (PC) beams with post-tensioned steel tendons. Nowadays, a considerable number of such bridges are becoming obsolete due to deterioration caused by environmental exposure during their service life. In particular, bridge beams with dapped-ends are more prone to rein-forcement corrosion due to the geometry of the nib, which can lead to a significant reduction in load-bearing capacity. In the present study, a numerical modelling approach is presented to evaluate the reduction of the load-bearing capacity of an existing Italian bridge by including defects and corrosion-induced effects vary-ing over time on post-tensioned tendons. To this purpose, Non-Linear Finite Element Analyses (NLFEA) of an existing PC bridge beam have been performed. The corrosion over time of post-tensioning wires is con-sidered by modifying their constitutive laws (in terms of residual stress vs strain) to reproduce the time-dependency of the load-bearing capacity of the bridge beam. The results demonstrate that numerical models can serve as digital twins of existing structures suitable to implement the effects of the spatial and temporal variability of corrosion process in the response prediction of existing structures