钢桥面板纵肋-顶板焊缝细节疲劳裂纹的应力强度因子分析

为研究正交异性钢桥面板纵肋-顶板焊缝位置的疲劳裂纹扩展特性,以某钢箱梁斜拉桥为工程背景,基于线弹性断裂力学与扩展有限元方法,通过ABAQUS软件建立纵肋-顶板三维裂纹扩展模型,引入半椭圆初始裂纹,对焊根与焊趾裂纹尖端的应力强度因子进行分析.分析结果表明,在车辆荷载的作用下,纵肋-顶板连接细节的疲劳裂纹是以Ⅰ型为主导的Ⅰ-Ⅱ-Ⅲ复合型裂纹;裂纹在横向位于车轮正下方,纵向位于两车轴中间时,疲劳裂纹扩展趋势最大;在车辆经过裂纹附近2 m范围内时,应力强度因子在最值间波动,对裂纹扩展产生较大影响.

Analysis on Stress Intensity Factor of Detail Fatigue Crack in Longitudinal Rib - Roof Weld of Steel Bridge Decks

In order to study the fatigue crack extension characteristics in the longitudinal rib-roof welding position of orthotropic steel bridge decks, taking a steel box beam cable-stayed bridge as an engineering background, based on the linear elasticity fracture mechanics and extended finite element method, a longitudinal rib-roof three-dimensional crack extension model is established through ABAQUS software. A semi-elliptic initial crack is introduced to analyze the stress intensity factors at the crack tip of weld root and weld toe. The results show that under the action of vehicle load, the fatigue cracks of longitudinal rib-roof connection details are the I-II-III compound cracks mainly by I-crack. When the cracks are laterally located just below the wheels and longitudinally between the axles, the fatigue crack extension trend is the greatest. When a vehicle passes within 2 m near the cracks, the stress intensity factor fluctuates between the maximum values and has the larger influence on the crack extension.