Bond Degradation-Induced Incompatible Strain between Steel Bars and Concrete in Corroded RC Beams

Bond degradation-induced incompatible strain between corroded steel bars and concrete is investigated in this paper. A compatibility coefficient and a nonlinear analysis method are introduced to quantify the incompatible strain. The effect of corrosion losses, loading levels, loading conditions, and the span-to-depth ratio on the incompatible strain are investigated in detail. The incompatible strain effects on the beam flexural strength have been clarified. A simplified formula is then proposed to calculate the ultimate compatibility coefficient. Further, an attempt has also been made to incorporate this coefficient into the flexural strength prediction for corroded RC beams. Results show that the incompatible strain depends on the loading levels and corrosion losses. Corrosion has a negligible effect on the incompatible strain until the corrosion loss exceeds a critical value. For severely corroded beams, the incompatible strain increases rapidly as the loading level increases and saturates to a constant value when the loading level is high. The critical corrosion loss and the final constant incompatible strain are significantly affected by span-to-depth ratio and loading condition, respectively.