某悬索桥钢箱梁疲劳病害及处治方法研究

针对柔性铺装正交异性钢桥面板的疲劳病害难以克服、横隔板弧形切口处疲劳裂纹主要由面外变形所致等认知问题以及横隔板疲劳裂纹的合理处治方法，以某悬索桥为工程背景，通过构造尺寸、运营荷载、疲劳病害等信息的汇集，移动轮载横隔板应力及其规律分析，以及横隔板疲劳裂纹处治方案比较研究，得到以下结论：①柔性铺装正交异性桥面板采用合理的结构形式与构造细节，可确保其通常运营荷载下的疲劳寿命|②横隔板弧形切口部位轮载应力主要为面内应力，该区域疲劳开裂主要原因为面外变形的传统结论值得商榷|③弧形切口区域轮载应力幅最大加载位置为纵向距关注横隔板0.3m，横向位于横隔板关注锯齿块正上方|④轮载对弧形切口处应力幅的影响范围为：纵向两端各1.5倍横隔板间距，横向两侧各2.0倍U肋间距|⑤横隔板疲劳裂纹处治可采用“优化弧形切口”或“优化弧形切口+双面补强钢板”方法，且弧形切口和补强钢板形状可全桥统一。

Study on fatigue damages and retrofit methods of steel box girder in a suspension bridge

For orthotropic steel deck with flexible pavement, it is very difficult to overcome fatigue damages , and the fatigue cracks originating from the diaphragm around cope holes are mainly caused by out-of-plane deformation. A suspension bridge is used to investigate the information of structures size, vehicular loads and the fatigue damages. The diaphragm stresses under wheel loads and their related laws are analyzed, and the retrofit methods of diaphragm fatigue cracks are contrasted. The conclusions are as follows: (1) Reasonable structure and detail of orthotropic steel deck with flexible pavement can ensure its fatigue life cycle under normal vehicle loads. (2) Wheel load stresses in diaphragm around cope hole are mainly composed of in-plane stresses, the traditional conclusion that out-of-plane deformation basically result in fatigue cracks in this area is debatable. (3) The highest stress in the diaphragm around cope hole happens when the wheel locates at 0.3m apart from the concerned diaphragm longitudinally and right above the concerned sawtooth block horizontally. (4)The influence range of wheel load on stress around cope hole is 1.5 times that of diaphragm spacing, and is 2.0 times that of U rib spacing. (5) “Optimized cope hole” or “optimized cope hole combined with double-sided reinforcing steel plate” can be adopted as the retrofitting scheme for diaphragm fatigue cracking. Optimized notch shape and reinforcing steel plate shape can be unified for the entire bridge.