Design and Experimental Study on the Online Monitoring System for Corrosion Environment of the Main Cable in a Trans-Strait Suspension Bridge

The main cable of a suspension bridge is the lifeline of the bridge.The corrosion or broken wires of the main cable in the suspension bridge are directly related to the operation safety and service life of the suspension bridge.In this study， a total of 20 corrosion monitoring sensors were installed in the main cable sheath of the Lingdingyang trans-strait Suspension Bridge in the Shenzhen-Zhongshan Channel using precise resistance corrosion monitoring probes，low-power data collectors，temperature compensation，and wireless networking technology.The probes utilized the bare steel wires of the main cable as the testing elements to monitor in real-time the corrosion rate and amount of corrosion of the high-strength steel wires in the sheath， establishing a distributed wireless monitoring network for main cable corrosion.Through five months of corrosion monitoring tests，it was found that the corrosion rate of the downstream main cable was significantly higher than that of the upstream section，with the most severe corrosion occurring at the lowest span of the main cable，where the average corrosion rate reached 147.91 μm/a.This indicated that， due to the failure to activate the dehumidification and desalination device during the early stages of bridge construction，the residual salt particles and moisture inside the main cable caused severe corrosion.Based on the visual online monitoring of corrosion data inside the main cable， guidance was provided for optimizing the protection scheme of the main cable， ensuring the safe operation of large suspension bridges.