Experimental study on seismic behavior of RC beams with corroded stirrups at joints under cyclic loading

Corrosion of stirrups can be a major factor in the degeneration of seismic behavior for reinforced concrete (RC) structures. In this work, low-cycle loading tests were conducted on six rectangular RC beam specimens at joints with different stirrups corrosion levels. The failure modes, hysteretic curves, skeleton curves, stiffness degradation curves, ductility factor, energy dissipation and bearing capacity of RC specimens are compared and discussed. Meanwhile, the influence of corrosion cracks on mechanical properties of members was also investigated. Experimental results show that with an increase of stirrup corrosion level, the energy dissipation capacity and plastic deformation capacity dropped significantly. For specimens with a lower corrosion level of stirrups, though, the energy dissipation reduced gradually and the ductility factor increased slightly, indicating that slight corrosion of stirrups improved the ductility of specimens. However, the energy dissipation and ductility coefficient declined remarkably as the stirrup corrosion level increased. Compared with the uncorroded specimen, the ductility factor and energy dissipation decreased observably, by 22.5% and 34.5%, respectively, for specimen with stirrup corrosion level of 15.4%. Furthermore, the failure modes gradually changed from ductile bending failure to brittle failure as the corrosion level of stirrups continuously increased. The disadvantageous influence of stirrup corrosion degree larger than 15.4% in RC structures should be considered in their seismic analysis.