摘要
正交异性钢桥面板纵肋构造细节疲劳危害严重,修复困难,传统单面焊构造疲劳抗力不足是导致该部位疲劳开裂频发的主要原因。采用双面焊构造可望显著提高该构造细节的疲劳抗力,而初始焊接缺陷是该类构造细节疲劳抗力的关键影响因素。以双面焊构造为研究对象,基于线弹性断裂力学理论,建立多裂纹扩展模拟方法,通过多裂纹扩展试验验证该方法的可行性;在此基础上,对焊根处存在单一和多个初始缺陷条件下构造细节疲劳裂纹扩展特性进行研究。结果表明:外侧焊根单裂纹、内侧焊根单裂纹与焊根多裂纹扩展模式均为Ⅰ型开裂主导的Ⅰ-Ⅱ-Ⅲ型复合裂纹扩展模式;多裂纹扩展特性并不显著,多裂纹在扩展初期由于临近裂纹等效应力强度因子幅值的迅速降低而转变为单一裂纹,此后其扩展规律与外侧焊根单裂纹扩展规律基本一致;3种裂纹在扩展初期裂纹形状比变化规律存在差异,但随着扩展深度的增加,等效应力强度因子幅值下降段变化规律基本一致,裂纹扩展达到一定深度后均呈扁平状且随扩展深度增加扁平状趋势更加显著;外侧焊根处的单一缺陷是控制钢桥面板纵肋双面焊构造疲劳抗力的主要缺陷,制造时应采取有效措施避免这类缺陷。
The welded joints between orthotropic steel bridge decks and longitudinal ribs are often heavily damaged by fatigue and difficult to repair.Fatigue resistance deficiency of the traditional one-sided welded joints is the main reason for frequent cracking in these components,and the double-sided welded joints are expected to significantly improve fatigue resistances of these joints.The initial welding defects are the key factors that affect the fatigue resistances of the double-sided welding joints.This study investigated the double-sided welded joints based on linear elastic fracture mechanics theory.The fatigue crack propagation characteristics were studied on single and multiple initial defects at the welding roots.Test result for multiple crack propagation in traditional one-sided welded joints verifies that the established multiple crack propagation simulation method is feasible.The propagation mode of the single crack of a welding root at the inner or outer side of the longitudinal rib and propagation mode of the multiple cracks of the roots are all of the mixed-mode crack propagations of ModesⅠ,Ⅱ,andⅢ,led by ModeⅠ.The multiple crack propagation characteristic is not significant,and these cracks transform into a single crack at the initial stage of propagation owing to the rapid decrease in the amplitude of the equivalent stress intensity factor of the adjacent crack.Subsequently,the propagation mode of multiple cracks is the same as that of a single crack in the welding root at the outer side of the longitudinal rib.The variations in the shape ratios of three kinds of cracks are different at the initial stages of propagation,but with the increase in propagation depth,the variations in the amplitudes of the equivalent stress intensity factor at the descending stages are basically identical.The shapes of the cracks are flat when they reach a certain depth,and the tendency to be flat becomes more pronounced with the increase in propagation depth.The single defect of the welding root at the outer side of
作者
张清华
郭亚文
李俊
袁道云
卜一之
ZHANG Qing-hua;GUO Ya-wen;LI Jun;YUAN Dao-yun;BU Yi-zhi(Department of Bridge Engineering,Southwest Jiaotong University,Chengdu 610031,Sichuan,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2019年第7期49-56,110,共9页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51878561,51778533,51578455)
桥梁结构健康与安全国家重点实验室开放课题重点项目(BHSKL18-01-KF)
“十二五”国家科技支撑计划项目(2011BAG07B03)
中央高校基本科研业务费专项基金项目(2682014CX078)
关键词
桥梁工程
正交异性钢桥面板
双面焊构造
疲劳性能
断裂力学
裂纹扩展特性
bridge engineering
orthotropic steel bridge deck
double-sided welded joints
fatigue performance
fracture mechanics
crack propagation characteristics
