Experimental Investigation on Shear Fatigue Behavior of Reinforced Concrete Beams with Corroded Stirrups

Stirrups in RC beams are more vulnerable to corrosion than longitudinal steel bars due to the thinner concrete cover, and the shear behavior may deteriorate faster than the flexural behavior under fatigue loading. An experimental study was conducted to investigate the deterioration mechanism of the shear fatigue behavior of RC beams with corroded stirrups. RC beams were corroded by an impressed current before fatigue loading was applied. The fatigue test results showed that all beams failed with fatigue fracturing of the stirrup, and the corrosion of stirrups had a significant influence on the shear fatigue behavior and fatigue life of RC beams. It was observed that fatigue cracks initiated and propagated rapidly around corrosion pits, and the stirrup fractured at the minimum cross section where the corrosion pits had formed. The strains in the stirrups, longitudinal steel bars, and concrete increased with an increase in the number of loading cycles, and a significant increase of the midspan deflection was observed in all beams. With the increasing corrosion degree of stirrups and load amplitude, the stress amplitude of the stirrups increased obviously, especially at the minimum cross section, and the stress concentration at the corrosion pits put the stirrups in a more adverse situation, resulting in faster deterioration of the shear fatigue behavior and a decrease in the fatigue life of RC beams with corroded stirrups.