钢桥面板对接焊缝表面多缺陷疲劳效应研究  

Research on Fatigue Effect of Multiple Defects on Butt Weld Surface of Steel Bridge Deck

作　　者：赵秋[1] 唐琨 李英豪 林铮哲 陈鹏 ZHAO Qiu;TANG Kun;LI Yinghao;LIN Zhengzhe;CHEN Peng(School of Civil Engineering,Fuzhou University,Fuzhou 350116,China)

机构地区：[1]福州大学土木工程学院,福州350116

出　　处：《铁道标准设计》2024年第3期133-140,162,共9页Railway Standard Design

基　　金：国家自然科学基金项目(51478120)。

摘　　要：为探明钢桥面板对接焊缝焊趾区域共面及异面表面多缺陷在裂纹扩展过程中的形态变化及相互作用机制,以钢桥面板U肋下翼缘对接焊缝简化后的基本焊接构造为研究对象,探明对接焊缝焊接区域的应力强度因子KI分布,并在验证ABAQUS与FRANC3D数值模拟方法可靠性的基础上,对焊趾区域植入的共面或异面多裂纹进行多裂纹扩展分析。研究结果表明:含余高对接焊缝在轴拉荷载作用下,焊趾线附近存在应力强度因子KI的峰值点;相邻共面裂纹在扩展至临界深度的过程中存在裂纹融合前、裂纹融合时及裂纹融合后3个典型的扩展阶段,不同阶段裂纹前沿形态及扩展速率da/dN变化可通过等效应力强度因子幅值ΔK_(eff)的分布来体现;共面裂纹融合前,单裂纹靠近另一裂纹长轴端点的裂纹相互作用比例因子随净间距s1与裂纹深度a比值呈幂次负相关性;对接焊缝异面裂纹中焊趾处裂纹对热影响区裂纹存在抑制作用,并随着裂纹尺寸差异的累计增加,焊趾处裂纹对热影响区的抑制作用呈线性扩大,最终使得热影响区裂纹ΔK_(eff)低于门槛值ΔKth而失去活性停止扩展,上述抑制作用随异面净间距s2的增加而减弱。To investigate the morphological changes and interaction mechanism of multi-defects on coplanar and dissimilar surfaces in the crack expansion process in the weld toe area of steel bridge panel butt welds,the basic weld configuration of the simplified butt weld under the flange of the U-rib of the steel bridge panel is used as the research object to explore the stress intensity factor KI distribution in the weld area of the butt weld,and based on verifying the reliability of ABAQUS and FRANC3D numerical simulation methods.Multi-crack expansion analysis of the weld toe area implanted coplanar or heterogeneous multi-crack shows that:for the residual height butt weld in the axial tensile load,there is a stress intensity factor factor KI peak point near the weld toe line;for adjacent coplanar cracks in the process of expansion to critical depth,there are three typical stages of expansion before crack fusion,during crack fusion and after crack fusion;different stages of crack front morphology and expansion rate da/dN changes can be reflected by the distribution of the equivalent force strength factor magnitudeΔK_(eff) in the crack front;before the fusion of coplanar cracks,the crack interaction ratio factor of a single crack near the end point of the long axis of another crack is negatively correlated with the net spacing s1 to the crack depth a ratio in a power;the crack at the toe in the butt weld heterogeneous crack has an inhibitory effect on the heat affected zone crack with different crack size.With the cumulative increase of crack size difference,the inhibitory effect of crack at toe on heat-affected zone expands linearly,and finally makes the heat-affected zone crackΔK_(eff) lower than the threshold valueΔKth and inactivates and stops expanding;and the above inhibitory effect decreases with the increase of net spacing s2 on the opposite side.

关 键 词：钢桥 桥面板 对接焊缝 多缺陷 断裂力学 等效应力强度因子 

分 类 号：U448.36[建筑科学—桥梁与隧道工程] U443.31[交通运输工程—道路与铁道工程]