Degradation of steel-to-concrete bond due to corrosion

Degradation of the bond between steel bars and concrete due to corrosion of steel significantly affects the durability of reinforced concrete (RC) structures. There are three mechanisms to transfer the interfacial shear (or bond) stress between steel bars and concrete, i.e., adhesion, friction and mechanical interlock (or dowel action). This paper discusses effects of corrosion on these three mechanisms. A new model for the bond-slip relationship between steel bars and concrete involving steel corrosion factor is proposed by modifying a recently developed unified bond-slip model. A rational approach is used in the modeling: the degradation of bond is caused by material degradation which can be modeled as degradation of concrete strength, and the degradation of confinement is taken into account in the concrete cover effect. A state-of-the-art database involving steel bar corrosion is built to evaluate the coefficients in the proposed bond-slip model. The calculated results using the proposed model show good agreement with experimental data.