Bond performance deterioration of rebar in concrete under the temperature synergistic effect: Experimental study

Existing bond-slip constitutive models suffer from discontinuities and inaccuracies due to the regression of experimental data. These deficiencies compromise the safety and convergence of structures that require consideration of the bond-slip relationship, such as those exposed to extreme temperatures (high and low temperatures). This paper concluded the bond performance formula calculated under different factors including rebar diameter, concrete cover, concrete strength, corrosion levels, and high/low temperatures by 84 prismatic pullout test specimens. Laboratory results indicate that the corrosion damage decreases the interfacial circumferential stress and bond stress, and the temperature damage the ultimate bond stress, bonded stiffness, and energy dissipation. The bond strength decreases by 43.9 % at a low temperature of -80 degrees C and 72.0 % at a high temperature of 800 degrees C. Interfacial pressures before and after cracking are analyzed based on thin-walled cylinder theory and temperature damage, and the restraining effects of the bonding interface are also functionalized. The crack width equation at the bonding interface is proposed considering the tensile softening behavior and bonding degradation at environmental conditions. Finally, the calculated bond strengths are compared with experimental data, and the proposed bond-slip constitutive model accuracy is verified by comparing IAE and finite element simulation. The proposed model predicts the bond properties of corroded RC structures at high and low temperatures, which is beneficial to the safety performance evaluation of service structures in extreme environments.