Abstract
Prestressed bridges have been a key element of transportation infrastructure for decades. Despite an expected service life of around 100 years under optimal design and maintenance, many structures exhibit damage that compromises their integrity or leads to failure. A common cause is material degradation resulting from inadequate design or environmental exposure, with corrosion being the most critical factor affecting the mechanical properties of prestressing reinforcement. This paper investigates the effect of corrosion on the nonlinear behaviour of standardised bridge girders and the overall capacity of the structure. To demonstrate the impact of reduced mechanical properties of the reinforcement, a nonlinear analysis was carried out using Atena software, in which degradation of material characteristics was simulated. The effect of corrosion was incorporated by modifying the stress–strain diagram of the prestressing reinforcement, up to complete elimination of its plastic region. This significantly affected both strain capacity and the ductility of failure of the load-bearing member. The results reveal a pronounced reduction in load-bearing capacity and a transition toward brittle failure in advanced stages of corrosion, underlining the critical importance of accurate diagnostics when making decisions related to maintenance and rehabilitation of existing bridges.