Experimental and numerical study of the fatigue properties of stress-corroded steel wires for bridge cables

In this paper, the fatigue tests of stress-corroded steel wires were carried out to investigate the effects of corrosion age, stress level, stress range on the failure mode, fatigue life and S-N curve of steel wires. Then, the fatigue fracture and crack growth rate of steel wires with different corrosion degrees were analyzed by SEM scanning, revealing the crack initiation and propagation mechanism of corroded steel wires. Finally, a numerical analyzing method for the fatigue life of steel wires considering the corrosion surface was proposed, and the relationship between the surface stress distribution and fatigue life was studied. The results shows that the fatigue life of steel wires decreased gradually with the increase of corrosion degree. When the corrosion degree was 5.0%, 10% and 20%, the fatigue life of steel wires decreased by 32.67%, 48% and 67.84%, respectively. The influence of corrosion degree on the fatigue life of steel wire was first sensitive and then insensitive. Meanwhile, compared with the unstressed corrosion state, the fatigue life of stress-corroded steel wires decreased by a maximum of 56.45%. In addition, stress corrosion affected the crack initiation location and shortened the crack propagation depth. The higher corrosion depth and the sharp surface were more likely to be the fatigue crack source. With the increase of corrosion degree, the striation spacing and crack growth rate of fatigue fracture increased, and the proportion of crack initiation and propagation zone decreased from 45% of the diameter to 28% of the diameter of the cable. Finally, the proposed numerical analysis method considering the real corroded surface can effectively reveal the fatigue failure mechanism and evaluate the residual fatigue life of corroded steel wires.