钢桥面顶板焊缝处共线双裂纹耦合扩展特性分析

为了研究钢桥面顶板与U肋焊缝处多疲劳裂纹间的耦合扩展效应，结合线弹性断裂力学理论与ABAQUS-FRANC3D交互技术，建立了钢桥面顶板-U肋焊缝处共线双疲劳裂纹的数值分析模型，对比分析了单裂纹和共线双裂纹的裂尖应力强度因子，揭示了裂纹间距、干扰裂纹尺寸对基础裂纹扩展特性的影响规律，并通过足尺节段试验对理论模拟进行了验证. 分析结果表明：共线裂纹相较于单裂纹的应力强化效应不可忽略，而相同尺寸双裂纹代表了多裂纹扩展的最不利情况，且当共线长裂纹的间距与裂纹长度比值s/c小于0.5时，裂纹交互影响因子及其扩展速率受耦合效应影响显著.

Analysis on Coupled Propagation Characteristics of Two Collinear Cracks on Steel Bridge Deck to-U Rib Welding Seam

Due to the aging of the in-service steel bridge deck, the size and density of widely distributed fatigue cracks at the weld gradually increase, leading to the interaction between the near-source multiple cracks. The coupling propagation and combination of multiple fatigue cracks are also promoted. In order to study the coupling propagation effect between multiple fatigue cracks, a numerical analysis model of two collinear fatigue cracks on steel bridge deck plate cover-U rib welding seam is established. Based on the theory of linear elastic fracture mechanics, ABAQUS-FRANC3D technology is used to calculate the stress intensity factor of single crack and two collinear cracks. The influence of crack spacing and size of interference crack on the propagation characteristics of the foundation crack is revealed, and the simulation conclusion is verified by a full-scale segmental test. The analysis results showed that the stress strengthening effect of collinear cracks cannot be ignored, compared with single crack. When all cracks have the same size, it is the most unfavorable case for multi-crack propagation. If the ratio of crack spacing to crack length s/c is less than 0.5, the stress intensity factor and crack growth rate are significantly affected by the coupling effect.