Digital Twin Model for Quantifying and Predicting Pit Depth of High-Strength Coated Steel Wire

Corrosion damage occurs in cable-supported bridges when the sheath cracks due to external impacts, aging, etc. during the service life of the cable. In the long time after the sheath cracks, it is necessary to quickly obtain the internal corrosion condition of the cable and decide when to replace the cable. The steel wires used in most cable systems are hot-dip galvanized steel wire, hot-dip galvanized aluminum (HDGA) steel wire, and hot-dip zinc-aluminum-magnesium steel wire, but the lack of atmospheric corrosion test data for these steel wires makes it difficult to predict the corrosion level of the cables and the time required for the formation of pitting. In this study, based on a large amount of atmospheric corrosion test data for zinc and steel, a method is proposed to quickly predict the corrosion degree of steel wires with different coatings, strengths, and diameters in different environments. Subsequently, a digital twin model is constructed based on the corresponding corrosion kinetics model. First, the corrosion kinetics model for coated steel wires was derived based on the atmospheric corrosion parameters (A, n) of zinc and steel, and the reliability of the theory was verified through acetic acid salt fog accelerated testing. Then, material and strength parameters were derived from the salt fog accelerated testing data, confirming the impact of diameter on corrosion. Finally, a digital twin model of the steel wire (HDGA, 1,770 MPa, ϕ5/ϕ7) was constructed for a marine environment, and the corrosion process over a period of 1 to 7 years was obtained.