Mechanical performance prediction of corroded concrete beam considering bond deterioration under fire

Fire and corrosion change the bond behavior and bearing capacity of marine concrete structures, and the multi-hazard coupling mechanism is unclear. Therefore, this paper aims to establish the relationship between the flexural capacity and bond performance of corroded beams by flexural and sustained load pullout tests. Furthermore, this study verifies the accuracy of corroded beams moment calculation equation considering the bond behavior. The sustained load pullout and flexural tests are performed under varying corrosion degrees. The test results indicate that the reinforcement slip and mid-span deflection of beams increase with increasing high temperature. Heating to 800 ℃ results in a slip of 2.2 mm, and the damage degree rises with increased temperature and corrosion degree. The damaged bond strength of corroded specimens with different temperatures, embedded lengths, and rebar diameters is subsequently calculated. The influence coefficient of corrosion and temperature on bond strength is determined using the damage principle, and the influence coefficient of bond performance on the moment-bearing capacity is also calculated. The bond strength calculation formula is obtained based on the nonlinear superposition principle, and a moment-bearing formula considering bond performance under fire is formulated. Finally, using the finite element method, five concrete beams under fire is simulated, and establish a nonlinear spring to reflect the bond-slip relationship, achieving a simulated deflection check for corroded beams under coupling action between fire and fatigue load. The finite element verification results of corroded beams under fire, using the unified bond-slip model, are in close agreement with the experimental results. •The interfacial damage regular of marine concrete structures was studied under multi-hazard conditions.•The moment bearing capacity considering the bond action is calculated under the multi-coupling action.•A finite element analysis method for susceptible damage beam is established.