正交异性钢桥面板疲劳裂纹试验和数值分析  

Experiment and Numerical Analysis of Fatigue Cracks in Orthotropic Steel Bridge Deck

作　　者：渠昱 顾安邦[1,2] 曾勇[1,2] 杜柏松[1,2] 

机构地区：[1]重庆交通大学土木工程学院,重庆400074 [2]山区桥梁结构与材料教育部工程研究中心,重庆400074

出　　处：《桥梁建设》2017年第5期65-70,共6页Bridge Construction

基　　金：国家自然科学基金项目(51478071)~~

摘　　要：横隔板开孔和U肋与横隔板连接焊缝端头部位是正交异性钢桥面板的疲劳敏感部位,容易过早、过多地出现疲劳裂纹。为了研究疲劳裂纹产生的原因,以某钢箱梁悬索桥为背景,针对其正交异性钢桥面板制作节段模型进行疲劳试验和扩展有限元分析,考虑横隔板面外变形的影响,研究横隔板开孔部位、U肋与横隔板连接焊缝端头部位疲劳裂纹的产生和扩展。结果表明:节段模型经200万次疲劳荷载作用后,横隔板开孔处出现长7.5mm的裂纹,260万次后扩展到31mm;考虑顶板和横隔板之间的相对水平位移(1.21mm)时,各测点的面内应力计算值与实测值整体吻合良好;横隔板开孔断面最小处的应力达60 MPa,热点应力达到或超过该细节的常幅疲劳极限70MPa,在此处产生裂纹;横隔板的面外变形是诱发横隔板开孔处裂纹的根本原因,热点应力和结构缺陷促使了裂纹的产生。The cutout in the diaphragm and the ends of the weld joint connecting the U rib and the diaphragm are the fatigue sensitive parts in the orthotropic steel bridge deck where the fatigue cracks are liable to occur untimely and excessively.To investigate the causes leading to the occurrence of the fatigue cracks,a steel box girder suspension bridge was cited as an example.With reference to the orthotropic steel deck of the bridge,the sectional model was prepared and the fatigue tests and extended finite element analysis were carried out.Considering the influences of the outof-plane deformation of the diaphragm,the occurrence and development of the fatigue cracks at the parts of the cutout and the ends of the weld joint were studied.The results indicate that after the sectional model experiences the 2 million times fatigue cycle load,the 7.5 mm long crack appears at the cutout in the diaphragm of the model and after the 2.6 million times cycle load,the crack extends to 31 mm.When the relative horizontal displacement（1.21 mm）between the top plate and the diaphragm is considered,the calculation values of the in-plane stresses at the various measurement points are well accordant with the measured values in general.The stress at the minimum cutout section of the diaphragm reaches 60 MPa,the hot spot stress reaches or exceeds the 70 MPa of the constant fatigue limit of the structural details there and the crack eventually occurs.The out-of-plane deformation of the diaphragm is the root cause inducing the crack at the cutout in the diaphragm while the hot spot stress and structural defects impel the crack to occur.

关 键 词：正交异性钢桥面板 节段模型 疲劳试验 扩展有限元 疲劳裂纹 横隔板 焊缝 

分 类 号：U441.4[建筑科学—桥梁与隧道工程] U443.32[交通运输工程—道路与铁道工程]