Bond performance of freeze-thaw damaged concrete and reinforcing bars subjected to high-cycle fatigue loading

Concrete bridges are susceptible to the detrimental effects of freeze -thaw cycles (FTCs) and dynamic vehicle loading in cold regions, compromising the bond between reinforcing bars and concrete. After high -cycle fatigue loading using eccentric pull-out tests, an experiment on the bond performance of freeze -thaw damage specimens was carried out. The investigation focused on the impact of FTCs, fatigue load cycles (FLCs), and concrete strengths on the bond behaviour. The test results showed that eccentric pull-out specimens of reinforced concrete with freeze -thaw damage under high -cycle fatigue loading were more susceptible to experiencing splitting failure. As the number of FTCs increased, the peak and the residual bond strength decreased continuously. Fatigue loading had a slight improvement effect on the peak bond strength, but it significantly reduced the residual bond strength when the specimens suffered from higher fatigue damage. The peak slip initially increased and subsequently decreased with FTCs, showing minimal sensitivity to the number of FLCs. Considering the stiffness degradation of the ascending section, a bond -slip model for freeze -thaw damaged concrete and reinforcing bars under high -cycle fatigue loading was established, and verified through experimental results.