Time-Varying Reliability Analysis of Corroded Bridge Cables Based on Fuzzy Failure Criteria

AbstractThe increasingly prominent durability problem of bridge cables not only leads to costly replacement but also causes safety concerns. This paper studies the time-varying reliability of corroded bridge cables by considering fuzzy failure criteria. First, the resistance degradation model of the corroded cable is established based on the corrosion rate of the steel wire and the corrosion propagation law of the cable section. Then, a time-varying reliability model of cable corrosion considering fuzzy failure criteria is proposed based on safety factor and the fuzziness of cable failure in an operation period. A case study was carried out to compare the proposed model and the one with clear failure criteria considering the time-varying reliability of service cable under different corrosion environment. The results show that the proposed model can reflect the variation of cable reliability in different corrosion environments and service times. Compared with the clear failure criteria, the gradual change rule of the time-varying reliability index under the fuzzy failure criteria is better and is more consistent with the engineering practice. It avoids the difficulty in selecting the safety factor under the clear failure criteria at a certain degree. The time-varying reliability index of corroded cables has obvious time division, and it gradually decreases with the corrosion degree of steel wires. The service life of the cable with local sheath damage is only 8–10 years. Due to the irreversibility of steel wire corrosion, avoiding sheath damage and strengthening early flaw detection capability are the key to ensure the cable durability.