Simplified Model of PC Concrete Beams with Corroded Strands in Highway Viaduct: Case Study and Analytical Modeling

In this paper, several cases of failure of prestressed reinforced concrete (PC) beams of a viaduct in Italy due to cable corrosion are presented. Therefore, a simplified model to determine the flexural response of corroded PC concrete beams is presented. The model takes into account loss of mass of corroded PC strands and bond between strand and concrete, reduction of mechanical properties of strands (yielding and ultimate stress, elastic modulus), and cracking of concrete. Analytical expressions used to predict the loss of bonding and the reduction in the mechanical properties of corroded PC strands are verified against the experimental data available in the literature and against numerical predictions using nonlinear finite-element code. Finally, a case study on the verification of an existing RC viaduct is presented and discussed, stressing that, in a real bridge, a reduction of mass of 9% of cable wires can dramatically reduce the bridge’s bearing capacity, with the risk of instantaneous collapse if some strand fails suddenly because of reduced ductility.