Fatigue damage analysis of prefabricated concrete composite beams based on metal magnetic memory technique

Current studies have shown that using magnetic field change around the ferromagnetic material to characterize the fatigue damage is very effective, but researches on using metal magnetic memory (MMM) technique to detect fatigue damage are mostly limited to the material level. There are few studies on the mechanism of the magnetic signal change or numerical simulations at the member level. In this paper, cyclic loading tests were carried out on 8 prefabricated concrete composite beam specimens using wet connection technology. The relationship between the variation in the magnetic field of the steel reinforcement and the interface peeling damage of the specimens were investigated. Based on the magnetic flux density, the interface deformation, and the longitudinal bar strain, the mechanism of the magnetic signal change in different stages as well as interface peeling's effect on the magnetic flux density were revealed. The feasibility of using the MMM field to characterize the fatigue damage of the composite spcimens was thus verified. Meanwhile, based on the modified J-A-S model, the model for magnetization change of prefabricated reinforced concrete components was established. By comparing the experimental and the simulation results, it is verified that the proposed model could effectively describe the magnetization change trend of the composite spcimens during the fatigue process.