Synergistic effect of fatigue loading and accelerated corrosion on reinforced concrete beams

Abstract

Some structures such as bridges and marine structures that are susceptible to corrosion are also subjected to repeated loading. Whenever corrosion damage can occur to the material surface of a dynamically loaded structure, corrosion fatigue can be a serious problem. It should be remembered that both of these phenomena attack the surface of the steel reinforcing bars in the initial stage, corrosion damage involve surface damage reducing the fatigue crack initiation time. Besides, when corrosion is developed along with fatigue loading, there is a synergistic effect between them, resulting in further corrosion and fatigue damage than when considered separately. The present study was designed to investigate the synergistic effect of corrosion and fatigue loading when considered as a coupled phenomena on fatigue strength, deflection evolvement and corrosion onset of reinforced concrete beams. For that, a new corrosion fatigue set up that allows the application of the load and corrosion at the same time is presented and tested. Specimen under 2.5 A, representing the most damaging environment , showed the highest increase in stiffness during the early stages and the highest stiffness degradation during the last 25 % of its life, even though it failed at the lowest corrosion rate. While the specimen under 1.0 A, representing the less damaging environment, showed a more gradual stiffness degradation. Combined with the fatigue strength results obtained, it is believed that the parameter representing corrosion damage should not be the corrosion rate at failure, but a parameter representing the degree of corrosion speed that could be present in a specific environment.Outgoin