Fatigue Life Estimation of Corroded Bridge Wires Based on Theory of Critical Distances

Based on the theory of critical distances, critical distance to influence fatigue damage zone determining was solved in light of the notch stress gradient of corroded wires so as to estimate the fatigue performance of bridge wires in service. FEM (finite element method) was used to propose a fatigue assessment to predict the life of corroded wires. The fatigue lives were obtained by fatigue tests for corroded galvanized steel wires on three corrosion levels as well as wire specimens with an artificial pit, including to round pit, triangle pit or triangle pit with a notch, and compared with the predicted lives. The research results show that the axial stress distribution has a significant effect on the fatigue strength of corroded bridge wires. The critical distance decreases when stress concentration raises. Stress concentration factor (SCF) is recommended to be an estimation indicator of residual life of wires, and the corroded wires with an SCF of above 3 should be replaced.