Estimation of Degradation in Load Carrying Capacity of Corroded PSC I-Girder

Assessing the structural health of aging bridges is crucial for determining their suitability for continued use or upgrades. This study investigates a typical prestressed concrete (PSC) I-girder bridge through experimental and numerical analyses, focusing on the impact of tendon corrosion. A 3D nonlinear finite element analysis (FEA) method is developed, incorporating an embedded model to simulate the concrete-reinforcement interaction and the cooling method to represent prestressing effects. The model is validated against field measurements obtained during different construction stages, demonstrating good agreement in terms of girder deflections and strain responses. A corrosion modeling strategy is further integrated, in which pitting corrosion is idealized using a hemispherical representation, and corrosion effects are incorporated by calibrating the prestressing tendon constitutive model against experimental results, implicitly considering the combined influence of random pitting and cross-sectional reduction. Numerical analyses of PSC girders with varying corrosion severities and locations indicate that tendon corrosion significantly degrades structural stiffness and load-carrying capacity. In particular, a corrosion level of approximately 15% in a single prestressing tendon may result in an estimated 20% reduction in the ultimate load capacity.