Characterization and grading assessment of rebar corrosion in loaded RC beams via SMFL technology

Accurate measurement and assessment of rebar corrosion are critical for the safety and durability of reinforced concrete (RC) structures. The non-destructive self-magnetic flux leakage (SMFL) technology is often employed but still has some difficulties in achieving this goal, especially when the RC structure is under load. Therefore, an SMFL measurement experiment and corresponding finite element simulation of six loaded corroded RC beams were carried out in this study. Then, a dimensionless SMFL quantitative index Gi for assessing the corrosion degree of the loaded RC beam was proposed. The experimental and simulated index Gi has a similar linear correlation with the corrosion degree of the longitudinal tensile rebars of the RC beams. The corrosion-induced increasing ratio of index Gi was up to 500% while that of the load-induced does not exceed 10.6%, which indicates that load has little effect on the SMFL-based corrosion degree assessment of RC beams. Furthermore, a universal grading assessment standard of the corrosion degree of loaded RC beams was established based on the Bayesian model and a Gi data set extracted from 500 random simulation combinations of corrosion distribution and load. According to this standard, the corrosion level of the loaded RC beam can be directly determined via the value of Gi with an accuracy between 70% and 100%. This work is beneficial for the engineering assessment of the rebar corrosion of loaded RC beams and provides an innovative research idea for this research field.