Zeng Yong, Kang Hongtao, Li Xueqin, Li Zhijie, Xiao Yunchuan, Zhou Jianting
State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
Mountain Bridge and Materials Engineering Research Center of Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China.
Materials (Basel). 2023 Jul 25;16(15):5217. doi: 10.3390/ma16155217.
Changes in loading position have a significant impact on the stress field of each vulnerable area of an orthotropic steel deck (OSD). The arc opening area of the diaphragm and the connecting area between the U-rib and the diaphragm under the moving load are prone to fatigue cracking. By comparing the stress responses under different methods, the hot spot stress (HSS) method is used as the main stress extraction method in fatigue performance evaluation. The control stress of fatigue cracking was analyzed by comparing the direction of the principal stress field with the crack direction in this experiment. According to the stress amplitude deviation under the biaxial stress state, a set of methods for evaluating the effects of in-plane biaxial fatigue was developed. An improved luffing fatigue assessment S-N curve was applied to analyze the fatigue life of the diaphragm's arc opening area. The results show that when the moving load is exactly above the connection of the deck and the web of the U-rib on one side, it is in the most unfavorable position in the transverse direction, and the diaphragm is mainly under the in-plane stress state. The longitudinal range of the stress influence line of the arc opening is approximately twice the diaphragm spacing. Two to three stress cycles are caused by one fatigue load. Fatigue crack control stress is the principal stress tangential to the arc opening's edge in this area. The normal direction of the principal stress in the model test is roughly consistent with the crack initiation direction. The variation in the stress amplitude deviation in this area is caused by changes in the action position of the moving load. When the moving load is at a certain distance from the involved diaphragm, it is reduced to zero, implying that the in-plane fatigue effect is the greatest in this area.
加载位置的变化对正交异性钢桥面板（OSD）各易损区域的应力场有显著影响。在移动荷载作用下，横隔板的弧形开口区域以及U肋与横隔板的连接区域容易出现疲劳开裂。通过比较不同方法下的应力响应，热点应力（HSS）方法被用作疲劳性能评估中的主要应力提取方法。在本试验中，通过比较主应力场方向与裂纹方向来分析疲劳开裂的控制应力。根据双轴应力状态下的应力幅值偏差，开发了一套评估面内双轴疲劳效应的方法。应用改进的变幅疲劳评估S-N曲线来分析横隔板弧形开口区域的疲劳寿命。结果表明，当移动荷载恰好位于一侧桥面板与U肋腹板的连接处正上方时，在横向处于最不利位置，横隔板主要处于面内应力状态。弧形开口应力影响线的纵向范围约为横隔板间距的两倍。一次疲劳荷载会引起两到三个应力循环。该区域疲劳裂纹控制应力为与弧形开口边缘相切的主应力。模型试验中主应力法线方向与裂纹起裂方向大致一致。该区域应力幅值偏差的变化是由移动荷载作用位置的改变引起的。当移动荷载距所涉横隔板有一定距离时，其减小为零，这意味着该区域面内疲劳效应最大。
