Bond slip of the corroded rebar and its effect on the load-bearing capacity of a flexural beam

An improved nonlinear spring model is used to simulate the bond-slip behaviour between nonuniformly corroded rebar and concrete to mitigate the stress concentration of concrete at rebar nodes caused by zero-thickness springs. Based on the relevant experimental results, the modified influence coefficient of the bond-slip constitutive model considering the effect of stirrup spacing is presented. On the basis of comparative research with the simulation of corroded reinforced concrete pull-out tests, a refined simulation of the three-point bending failure process of corroded reinforced concrete beam specimens is carried out. The results indicate that the improved nonlinear spring model can better simulate the bond-slip behaviour between rebar and concrete. The bending capacity of the beam obtained by the bond-slip constitutive model considering the effect of stirrup spacing shows good agreement with the experimental values. There is a certain degree of fluctuation in the stress distribution of the rebar in nonuniformly corroded reinforced specimens, and the stress values are reduced. The corrosion of longitudinal rebar and stirrups has different effects on the load-bearing capacity of reinforced concrete beams, with the corrosion of longitudinal rebar being more detrimental to the bending capacity of the beams. When the reinforcement ratio remains unchanged, the change in the number of longitudinal rebars alters the beam's bending capacity. When the number of rebars in the bending beam is less than four, the prediction formula for the bending capacity of the beam based on Chinese specifications must be revised, and the correction coefficient is between 0.51 and 0.88. The simulation results of four-point bending test further corroborate the rationality of the bond-slip constitutive model employed in this study.