钢桥面板横隔板弧形缺口位置疲劳受力分析

RESEARCH ON THE FATIGUE STRESS OF ARC-SHAPED NOTCH OF DIAPHRAGM IN STEEL BRIDGE DECK

为分析横隔板弧形缺口位置疲劳细节的应力特征,建立了正交异性钢桥面板节段有限元模型,选取3个易开裂部位：横隔板弧形缺口焊缝的U肋焊趾、横隔板焊趾和弧形缺口薄弱截面,分析了3个疲劳细节处的应力随车轮荷载纵向、横向移动时的变化情况。基于获得的最不利荷载工况组合,分析了3个疲劳易开裂点不同纵桥向加载位置时的应力与变形特征,并与实际裂纹开裂情况进行对比。分析结果表明：采用双联轴单侧双轮荷载进行加载时,3个关注点处纵桥向最不利加载位置存在较大差异,而横桥向最不利加载位置保持一致;横隔板与U肋焊缝末端的位移矢量和在不同纵桥向加载位置时均达到最大值;而该处的面内和面外变形最大值对应的加载位置存在差异;有限元计算得出裂纹起裂方向与实际情况存在一定差异,表明焊接及弧形缺口切割产生的残余应力影响显著。

To analyze the stress characteristics of arc-shaped notch of diaphragm,the section model of orthotropic steel bridge deck was developed by ABAQUS. Three fatigable details,namely the weld toe closet to the U-rib,the weld toe closet to the diaphragm and the arc-shaped notch,were focused in the study. The stress of the three fatigable details was analyzed relative to different longitudinal and transverse loading directions. Based on the most critical loading conditions,the characteristics of both stress and deformation of the aforementioned fatigable details were analyzed. In addition,the analytical results were compared with crack initiation in real structures. The results showed that with regard to double wheel loads,the most critical loading positions of the three details in longitudinal direction were different,while they were the same in transverse direction. The vector sum of the displacement at the end of the diaphragm-to-rib weld reached the maximum value corresponding to different longitudinal loading positions. However, the critical loading position corresponding to the maximum out-of-plane and in-plane deformation was different from each other. The directions of crack initiation in finite element were different from them in real structures, indicating that the residual stress produced by welding and arc notch cutting was significant.