**6. Conclusions**

In this chapter, through the corrosion fatigue experiment on the steel wire of bridge cable under the action of coupled environment and load explore the fine morphology of the steel wire under different corrosion time and different stress loading, analyze the law of evolution of mechanical property and the different fracture morphology of the steel wire, and analyze and generalize the service life and damage assessment technology of the cable based on the breakage safety theory, the main conclusions are as follows.

As the steel wire of the cable undergoes electrochemical reaction during corrosion, the surface of the steel wire produces white corrosion products. As the corrosion deepens, the galvanized layer on the surface of the steel wire is depleted, the white corrosion products disappear and are replaced by a larger area of red corrosion, and the surface of the entire steel wire appears uneven as visible to the naked eye.

The corrosion characteristics of the steel wire are basically in line with the normal distribution, in the salt spray environment, the steel wire did not appear obvious corrosion pits under stress-free conditions, the corrosion rate is about 32.58%; the corrosion rate of alternating stress conditions under alternating stress conditions is about 55.49%; Under the static stress, the corrosion rate of steel wire is somewhere in between, about 40.12%. Under stress-free condition, steel wire corrosion is more uniform, and the frequency of steel wire corrosion and corrosion rate is greater than the rest of the conditions, the degree of corrosion performance: Stress-free < static stress < alternating stress under stress-free condition.

Corrosion in the early stage, stress corrosion, and corrosion fatigue have little influence on tensile strength. In the middle and late stages of corrosion, the tensile strength began to decline sharply, the tensile strength of the steel wire appears briefly increased phenomenon under alternating stress and static stress conditions, and the ductility of steel wire decreased. In the late stages of corrosion, the alternating stress causes fatigue damage to the steel wire during the corrosion process, the toughness of the steel wire is significantly reduced, elongation after fracture of the steel wire is significantly lower than the other two loading states, at this time, the possibility of brittle fracture of the steel wire is high.

The stress of the steel wire bundle of the cable is in a dynamic redistribution process with the development of corrosion, and the cable will fracture rapidly when *Corrosion Fatigue Behavior and Damage Mechanism of the Bridge Cable Structures DOI: http://dx.doi.org/10.5772/intechopen.109105*

the tensile force reaches the maximum bearing capacity. In order to ensure the safety of the cable in service, it is necessary to predict the crack expansion and the remaining service life of the cable in service based on the linear-elastic fracture mechanics, and to evaluate the safety performance of the existing damaged cable using different methods according to the actual project.
