基于临界域法的桥梁钢丝腐蚀疲劳寿命

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

为评估桥梁钢丝服役期间的腐蚀疲劳性能,采用临界域法,根据钢丝腐蚀坑局部应力梯度求解临界距离.采用精细有限元法,建立了钢丝腐蚀疲劳寿命预测模型;通过圆形、三角形和含切口的三角形3种形状腐蚀坑钢丝的疲劳试验,获得了它们的疲劳寿命,并与疲劳寿命的预测结果进行比较.研究结果表明:轴向应力分布决定钢丝的疲劳强度;临界距离随应力集中效应增强而减小;腐蚀钢丝的剩余寿命可根据应力集中系数评估,应力集中系数大于3的腐蚀钢丝应考虑更换.

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.