Serviceability Limit State criteria based on steel–concrete bond loss for corroded reinforced concrete in chloride environment

This paper will focus on the study of reinforced concrete beams stored in a chloride environment for a period of 14–23 years under service loading. According to the experimental results, a Serviceability Limit State (SLS) criteria is proposed based on an excessive steel–concrete bond reduction. Corrosion of reinforcement in chloride environment leads to a specific local steel cross-section loss as well as a steel–concrete bond loss. Experimental results have shown that, in the first stage of corrosion propagation period, the deflection is more sensitive to chloride-induced corrosion than the ultimate capacity due to the effect of the tension steel–concrete bond loss even if both are correlated. Given this high sensibility of the bending stiffness to corrosion pitting attacks, it appears that a Serviceability Limit State (SLS) criteria based on excessive deflection of structural members is an adequate factor for SLS assessment. Later in corrosion propagation period, when the bond is already significantly reduced, only the ultimate capacity is affected by the steel cross-section loss. This does not affect the serviceability, because pitting attacks are very localised with an insignificant influence on the global deflection. Then, once the steel–concrete bond is lost in critical parts of the beams (high bending moment areas), pitting corrosion propagation does not affect anymore serviceability (stiffness reduction, bending or corrosion cracks patterns) but still leads to an ultimate capacity reduction, which is not acceptable. As a result, excessive steel–concrete debonding can be considered as the SLS criteria.