坝陵河大桥钢桁加劲梁主横桁架焊接整体节点疲劳试验

Fatigue Test on Welded Integral Joint of Transverse Truss of Baling River Bridge

贵州坝陵河大桥为主跨1 088 m的单跨简支钢桁加劲梁悬索桥,钢桁加劲梁的主横桁架与主桁架上弦杆之间采用焊接整体节点连接。为研究该焊接整体节点的疲劳性能,进行了足尺模型疲劳试验。根据该桥设计交通量,采用BS 5400规范中的标准疲劳车,按损伤等效原则,并考虑多车效应及缩尺比例,推算了试验疲劳荷载。试验结果表明,经过200万次的循环加载后,节点模型未出现任何疲劳裂纹,应力状态稳定,结构疲劳性能满足设计要求。该焊接整体节点形式对我国今后大跨钢桁梁桥类似节点的设计和研究有重要参考意义。

The Baling River Bridge is a single-span simply-supported suspension bridge with a main span of 1 088 m. The welded integral joint is used to connect the transverse truss and the main truss in the steel stiffening girder. The integral joint is a key structure and determines the safety of the bridge, but it is very complex in detail and has an undefined fatigue resistance. In order to investigate its fatigue reliability, a fatigue test is performed on a full scale model of the integral joint of the main transverse truss of the bridge. With an assumption of the load spectra represented by the standard fatigue vehicle in BS 5400, the test fatigue load is derived accounting for the multiple vehicle effect and the model scale. The test result shows that no cracks are detected in the model when subjected to two million stress range cycles, and the structure has an reliable fatigue resistance satisfying the design requirement. This type of integral joint is an alternative for long span truss bridges.