Corrosion and Fatigue Coupling: Assessment of a Prestressed Concrete Cable Stay

Abstract

Recent collapses of reinforced and prestressed concrete bridges have been attributed to corrosion and construction flaws, which are often belied by an outward appearance of robustness. The true nature of degradation being obscured, routine monitoring may fail to capture serious defects. Two simple analytical methods are presented herein for the prediction of corrosion damage evolution as a means of supplementing routine inspections. The first approach captures load redistribution between concrete and corroded reinforcement, based on the principles of compatibility and equilibrium. Corrosion is modeled by decreasing the effective reinforcement area and reducing the reinforcement strength and ductility according to models from the literature. The second method couples corrosion and fatigue damage by treating corrosion pits as fatigue initiation sites. It is shown that corrosion pits reach a critical point when their depth approaches one-half of the reinforcement diameter. Both schemes are implemented in a case study of the Morandi Bridge, inspections of which revealed the presence of internal corrosion damage and construction flaws upon its partial collapse in 2018.