STRESS MONITORING OF THE TENSILE REINFORCEMENT IN A BRIDGE BASED ON SELF-MAGNETIC-FLUX LEAKAGE

Jun Chen, Kui Tan, Senhua Zhang, and Siyu Zhao

Keywords

Reinforced concrete beam bridge, self-magnetic-flux-leakage, stressstate, monitoring

Abstract

The stress of the reinforcements of a bridge affects its safety. In this research, the stress state of internal reinforcements was studied based on the Jiles–Atherton (J–A) force magnetic coupling model and the dislocation theory. The self-magnetic-flux leakage (SMFL) monitoring method was employed to monitor the stress. After analysing the relationship between the stress and the SMFL signals, an SMFL monitoring experiment was carried out for the reinforced concrete beam. The experimental results agreed with the theory, which showed the boundary characteristics and variation characteristics of the SMFL signal curve. The SMFL signals were sensitive to the stress of the reinforcements. When the stress reached one-third of the ultimate load, a significant signal on the SMFL curve was observed. When the stress reached one-half of the ultimate load, a “smaller stress-larger stress limit of the SMFL signals was observed. After unloading, the SMFL curve showed the characteristic signals that corresponded to the residual deformation. Thus, the stress state of the internal reinforcements could be determined according to the change in the SMFL signals. The proposed method provided a reliable basis for the subsequent evaluation of the stress state of the reinforcement, damage state, and safe operation state of the bridge.

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