中文摘要：

U肋对接焊缝处易出现疲劳裂纹,为了分析该部位裂纹体应力强度因子对各关键参数的敏感程度及其简化计算公式,以港珠澳大桥为背景,利用ANSYS有限元软件,逐步建立了该桥正交异性钢桥面板U肋对接焊缝处三维半椭圆形裂纹体的精细化仿真分析模型,采用相互作用积分与有限元相结合的方法计算半椭圆形裂纹体应力强度因子,进行系统的参数分析,探讨了应力强度因子随各关键设计参数的变化规律,并根据有限元分析结果得出了应力强度因子计算公式。结果表明：应力强度因子对裂纹前缘位置和裂纹深度较敏感,而对顶板厚度、U肋厚度及U肋顶板宽度的敏感性较弱,基于响应面法得到的拟合公式计算应力强度因子具有较高的计算精度。

英文摘要：

The butt weld joint of U rib is prone to fatigue crack. To analyze the degree of sen- sitivity of the stress intensity factors of the cracked body in the butt weld joint to the various criti- cal parameters and also to analyze the related simplified calculation formula for the stress intensity factors, the Hong Kong-Zhuhai-Macau Bridge was taken as the research object and the refined sim ulation analysis model for the 3-dimensional semi-elliptic cracked body in the butt weld joint of the orthotropic steel deck U rib of the bridge was built up gradually, using the finite element software ANSYS. The stress intensity factors of the semi-elliptic crack body were calculated by the com- bined method of the interaction integral and finite elements and the parametric analysis was sys- tematically carried out. The laws of the stress intensity factors changing with the various critical design parameters were studied and the calculation formula for the stress intensity factors was ob- tained according to the finite element analysis. The results of the study demonstrate that the stress intensity factors are more sensitive to the crack front position and crack depth, but are less sensi- tive to the thickness of the top plate, thickness of the U rib and width of the U rib top plate. The stress intensity factors calculated by the fitted calculation formula based on the response surface method has high accuracy of calculation.