Quantitative Evaluation Method for the Circumferential Multi-Point Corrosion States of Stay Cables Based on Self-Magnetic Flux Leakage Detection

Stay cables are critical load-bearing components in cable-stayed structures, making corrosion distribution vital for damage diagnosis and maintenance. To address the insufficient characterization of circumferential multi-point corrosion distribution in stay cables, a theoretical model of circumferential multi-point defect magnetic charge for the stay cables was established, and a self-magnetic flux leakage experiment was conducted on 37-wire steel specimens with circumferential corrosion. The effects of corroded wire number (N), corrosion time (T), and circumferential angle number (K) on the axial Bx component of the magnetic flux leakage signal were analyzed. The relationship between the θ-Bx-max peak distribution and corrosion patterns was clarified. Quantitative models for corrosion number (c), center (θc), and the cross-sectional corrosion rate (α) were established. The results indicate that c improves the determination of the number of concentrated corrosion sites in the ‘peak platform’ corrosion distribution type. Based on the Lorentz fitting, the maximum prediction error of θc is 15.1%, and the prediction accuracy of the cross-sectional corrosion rate α exceeds 90%. The study provides a reference for the quantifiable characterization and evaluation methods of the circumferential multi-point defect distribution in stay cables.