Degradation of the Mechanical Properties of Prestressed Anchor Cable in an Alternating Wet–Dry Condition

As an active reinforcement technology, prestressed anchor cables are susceptible to environmental corrosion during long-term service. Corrosion occurs and progresses more rapidly, especially in an alternating wet–dry environment, which can degrade the mechanical properties of prestressed anchor cables and may ultimately lead to failure. Current methods typically evaluate the mechanical properties of anchor cables based on cross-sectional loss calculated from the average weight loss ratio. However, this uniform-corrosion assumption may underestimate the effect of corrosion on mechanical performance. In this study, a testing apparatus for corroding prestressed anchor cables under alternating wet–dry conditions was developed. The apparatus enabled accurate loading and nondestructive sampling. Using this apparatus, alternating wet–dry corrosion tests and mechanical tensile tests were conducted on anchor cables under different stress levels. The relationship between weight loss ratio and mechanical properties was then analyzed. Based on this relationship, an equation was derived to calculate the breaking strength of corroded anchor cables in alternating wet–dry environments. The service life estimated using this equation was closer to that observed in actual anchor cable failure cases. This indicates that the proposed equation provides more accurate predictions than methods based on the uniform-corrosion assumption.