钢桥腐蚀-疲劳耦合计算模型及影响因素分析

为了研究钢桥在交通荷载和腐蚀环境共同作用下的疲劳性能，考虑钢桥腐蚀-疲劳耦合效应，建立有2个阶段的腐蚀-疲劳耦合计算模型. 在点蚀坑萌生阶段，考虑循环交通荷载对腐蚀过程的加速作用；在裂纹扩展阶段，引入裂纹扩展腐蚀加速因子，考虑腐蚀环境对裂纹扩展的影响. 对钢桥顶板和纵肋焊接节点的腐蚀疲劳寿命算例分析表明：考虑腐蚀-疲劳耦合作用的疲劳强度相对于疲劳试验、规范AASHTO、规范BS5400和不考虑腐蚀-疲劳耦合作用的情况，分别降低41.25%、28.80%、44.60%和10.90%. 对所建模型开展加载频率、腐蚀环境、腐蚀坑形貌特征等影响因素的比较研究，结果表明：随着加载频率的增加，焊接节点的腐蚀疲劳强度递增，当加载频率大于0.6 Hz时，焊接节点的腐蚀疲劳强度相近；随着腐蚀环境变强，腐蚀电流和腐蚀速率逐渐增大；腐蚀疲劳强度随着腐蚀坑形貌特征的增大而增大.

Corrosion-fatigue coupling calculation model of steel bridge and its influencing factor analysis

A two-stage corrosion-fatigue coupling calculation model was established considering the corrosion fatigue coupling effect of steel bridges, in order to study the fatigue performance of steel bridges under the combined action of traffic load and corrosive environment. In the stage of pitting, the acceleration effect of cyclic traffic load on the corrosion process was considered. In the stage of crack propagation, the corrosion acceleration factor of crack growth was introduced, and the influence of corrosion environment on crack growth was considered. The corrosion fatigue life calculation example of welded joints of top plate and longitudinal rib of steel bridge shows that the fatigue strength considering corrosion fatigue coupling decreases by 41.25%, 28.80%, 44.60% and 10.90% respectively compared with fatigue test, code AASHTO, code BS5400 and no corrosion fatigue coupling. In addition, a comparative study was carried out on the influence factors of the established model, such as loading frequency, corrosion environment, and corrosion pit morphology. Results show that the corrosion fatigue strength of welded joints increases with the increase of loading frequency, and the corrosion fatigue strength is close when the loading frequency is greater than 0.6 Hz. With the corrosion environment becoming stronger, the corrosion current and corrosion rate gradually increase. The corrosion fatigue strength increases with the increase of corrosion pit morphology.