Laboratory tests on the fatigue behavior of damaged reinforced concrete beams under constant-amplitude fatigue loading

In this study, constant-amplitude fatigue tests were first performed on two types of reinforced concrete beams containing corroded reinforcements and carbonized concrete (involving corroded reinforcements). Then, the stiffness degradation behavior and the failure modes of these beams were analyzed. The results show that the stiffness of a beam first rapidly decreased and then slowly decreased under constant-amplitude fatigue loading. In addition, the corrosion ratio of the reinforcement could affect the failure mode, and fatigue failure occurred in the compression zone of the concrete. Subsequently, a degradation equation of the bending stiffness for a damaged beam and a deflection equation that considers fatigue loads and accumulated damage were proposed. Furthermore, a staged linear curve for predicting the fatigue life of a reinforced concrete beam within certain corrosion ratio ranges was developed.