钢桥面板焊缝多疲劳裂纹耦合扩展试验  

Experimental Study on Coupled Propagation of Multiple Fatigue Cracks in Weld Seam of Steel Bridge Decks

作　　者：鲁乃唯 戴歆文 王鸿浩 罗媛 LU Nai-wei;DAI Xin-wen;WANG Hong-hao;LUO Yuan(School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,Hunan,China;School of Civil Engineering,Hunan University of Technology,Zhuzhou 412000,Hunan,China)

机构地区：[1]长沙理工大学土木工程学院,湖南长沙410114 [2]湖南工业大学土木工程学院,湖南株洲412000

出　　处：《中国公路学报》2024年第5期267-277,共11页China Journal of Highway and Transport

基　　金：国家重点研发计划项目(2021YFB2600900);国家自然科学基金项目(51908068,52178108);湖南省自然科学基金项目(2021JJ30720,2023JJ50180,2024JJ5033);湖南省教育厅项目(23B0575);湖南省科技创新计划项目(2022RC1181);湖南省研究生科研创新项目(QL20230203);长沙理工大学研究生科研创新项目(CXCLY2022048)。

摘　　要：随着在役钢桥面板老龄化进程,顶板焊缝处疲劳裂纹大量萌生并持续扩展,诱发多裂纹间的耦合扩展与融合现象,形成的长裂纹是在役桥梁的重大安全隐患。为研究钢桥面板焊缝处近源多裂纹耦合扩展特性,制作了含初始缺陷的钢桥面板足尺模型,开展了多裂纹耦合扩展试验研究,监测了裂尖的静态与动态热点应力,对比了裂纹近端点与远端点的扩展速率,捕捉了多裂纹间的耦合扩展行为。采用FRANC3D-ABAQUS交互技术模拟分析了多裂纹间的应力强度因子放大效应,对比分析了裂纹尺寸与深度对多裂纹耦合扩展速率的影响规律。试验与数值分析结果表明:多裂纹耦合效应主要作用于相邻裂纹尖端区域,耦合效应随着裂尖间距的缩小而持续增加;试验模型裂纹萌生初期的测点应力幅下降约15%,裂纹耦合阶段的近端点与远端点应力幅降幅分别为68.4%和21.6%,焊缝应力幅的衰减与裂纹扩展速率呈正相关,当裂纹贯穿顶板时焊趾处应力幅趋近于零;多裂纹之间的耦合效应随着裂纹深度的增加而趋于明显,形态比为a/c=1.5的裂纹耦合效应最明显,其交互因子达到1.169。With the aging of in-service steel bridge decks,numerous fatigue cracks are formed at the rib-to-deck welds,and these cracks continue to propagate.The adjacent multi-cracks affect each other and may merge into a long crack,which is a major hazard for the safety of the bridge in service.To understand the coupled propagation characteristics of adjacent multi-cracks,a fullscale specimen of a steel bridge deck with initial defects was prepared,and an experimental study on the propagation of multi-cracks was conducted.Both static and dynamic hot-spot stresses at the crack tips were monitored,and the crack propagation rates of the near-end and far-end points were compared.The coupled propagation behavior of the multiple cracks was captured.Based on the FRANC3D-ABAQUS interactive technique,numerical simulations were conducted to investigate the amplification effect of the stress intensity factor between multiple cracks.The simulations were aimed at analyzing the influence of crack size and depth on the coupled propagation rate.The experimental and numerical analysis results show that the multiple crack coupling effect mainly exists on the adjacent crack tip.The coupling effect increases with the decrease in the spacing between two cracks.A decrease of about 15%in the stress amplitude at the measurement point is a stress indicator of crack initiation.In the stage corresponding to multi-crack coupled propagation,the stress amplitude on the near-end and far-end points of the crack is 68.4%and 21.6%,respectively.The attenuation of the fatigue stress amplitude has a positive relationship with the propagation ratio.The near-zero stress amplitude at the weld toe is a reflection of the fatigue crack stress through the top plate.The increase in crack depth enhances the coupling amplification effect between multiple cracks.Two identical cracks with a/c=1.5 constitute the most unfavorable case for the coupling effect of multiple cracks,and its interaction factor can reach a maximum of 1.169.

关 键 词：桥梁工程 正交异性钢桥面板 模型试验 多裂纹耦合扩展 热点应力 

分 类 号：U441.4[建筑科学—桥梁与隧道工程]