基于热点应力法的钢箱梁横隔板焊接节点疲劳性能研究

Research of fatigue performance of welded joints for steel box girder diaphragms based on hot spot stress method

在运营活载作用下,正交异性钢桥面板的破坏往往体现为各板件焊缝的疲劳破坏。尤其纵肋与横隔板焊接细节的焊址是疲劳裂纹最容易萌生的部位。为了研究该焊接细节的疲劳性能,以苏通大桥为工程案例,建立钢箱梁纵肋与横隔板焊接细节有限元模型。通过采用热点应力法对纵肋与横隔板焊接细节焊缝周围的热点应力进行详尽的数值模拟,在全面分析单元类型与单元尺寸对数值计算结果的影响的基础上,通过现场试验测试对数值计算结果进行对比验证。最后采用热点应力法与名义应力法分别预测该焊接细节的疲劳寿命,并与纵肋与顶板焊接细节对比,结果表明采用热点应力法FAT90计算结果更准确,且该焊接细节相对于其他焊接细节更容易发生疲劳破坏。

Under the action of operational live load,the failure of orthotropic steel bridge decks often manifests as fatigue failure of the welds of each panel,especially the welding site of longitudinal ribs and transverse diaphragms is the most prone area for fatigue crack initiation.In order to study the fatigue performance of the welding details,a finite element model of the welding details of the longitudinal ribs and transverse diaphragms of the steel box girder was established using Sutong Bridge as an engineering case.a detailed numerical simulation of the hot spot stress around the welding details of longitudinal ribs and transverse diaphragms was conducted by using the hot spot stress method.Based on a comprehensive analysis of the influence of element type and size on numerical calculation results,on-site experimental tests were conducted to compare and verify the numerical calculation results.Finally,the fatigue life of the welding detail was predicted using both the hot spot stress method and the nominal stress method,and compared with the welding details of longitudinal ribs and top plates.The results showed that the FAT90 calculation using the hot spot stress was more accurate,and this welding detail was more prone to fatigue failure compared to other welding details.