**1. Introduction**

The construction of large-span cable-stayed bridges around the world is at its peak, and a large number of cable-stayed bridges are already in the operational maintenance phase. The cable-stayed structure is one of the main load-bearing structures of cablestayed bridges, and its durability directly affects the safety of bridge operation. As the cable system is subjected to long-term alternating loads and exposed to the natural environment, it is highly susceptible to environmental erosion. In particular, the acid rain area in China has accounted for one-third of the national territory, becoming the third largest heavy acid rain deposition area in the world after Europe and North America. In such areas with serious atmospheric pollution and water pollution or marine environment, the steel wire inside the cable-stayed bridge is highly susceptible to erosion by corrosive media, such as SO4 <sup>2</sup> and Cl in the environment. When the wire inside the cable breaks due to severe corrosion, it can lead to the failure of the cable system, affecting the safety and service life of the bridge, and the dangerous

situation can cause serious economic losses and safety accidents. Therefore, cable corrosion and wire breakage have become the problems faced by most cable-stayed bridges.

In this chapter, the investigation and statistical analysis of the working performance and corrosion fatigue damage of cable under service environment are carried out for cable-stayed bridges, suspension bridges, arch bridges, and other bridge cable structures, and indoor artificially accelerated corrosion fatigue test research under the coupling effect of load and environment is conducted to reveal the corrosion fatigue damage mechanism of galvanized parallel wire cable under the coupling effect of salt spray environment and static stress and alternating stress. The physical and mechanical properties of the damaged cables were studied. The technical condition assessment method based on the image grayscale analysis is established and further combined with the cable damage evolution model, the service life prediction method and assessment technology based on the breakage safety of cable are established to provide a theoretical basis for the scientific evaluation of the technical condition of cable-stayed bridges, prolonging the service life of the cable and improving the anticorrosion design of the cable.
