正交异性钢桥面板U肋对接焊缝疲劳寿命评估

Fatigue Life Evaluation of U-Rib Butt Weld of the Orthotropic Steel Bridge

基于江阴长江大桥U肋对接焊缝实时动态应变监测,结合雨流计数法以及BS5400规范,对江阴长江大桥正交异性钢桥面板U肋对接焊缝疲劳寿命进行了研究。通过标准车辆荷载模型以及车流仿真模拟,获得移动车辆荷载作用下焊缝处的应力变化,进行了损伤度计算,并将数值计算与实测分析结果作了详细对比。实测结果表明:慢车道与快车道应力幅分别为70与110 MPa,均超过了该部位的疲劳极限值,随着疲劳损伤累计可能发生破坏。计算结果显示车辆经过桥面时焊缝处产生了较大的应力幅,但以损伤累计以低循环累计为主。慢车道U肋对接焊缝处疲劳寿命低于大桥设计寿命,应当及时给予关注。

The fatigue life of U-rib butt weld of orthotropic steel bridge deck of Jiangyin Yangtze River Highway Bridge was researched,which was based on real-time monitoring of dynamic strain of U-rib butt weld on the Jiangyin Yangtze River Highway Bridge,with the consideration of the rain-flow counting method and BS5400 specification. The stress variation of U-rib butt weld with the load of moving vehicle was obtained by using the fatigue-loaded vehicle model and the traffic flow simulation. The fatigue damage degree was calculated,and the calculation results were compared with the measured ones in detail. The measured results show that the maximum stress amplitude of the slow traffic lane and the fast traffic lane both exceed the fatigue limit of U-rib,which is 70 and 110 MPa respectively,which may cause failure with the accumulation of the fatigue damage. The FEM result shows that although large stress amplitude is produced when the vehicle passes through the bridge,the damage accumulation is mainly in low cycle. The fatigue life of the U-rib which locates on the slow lane is lower than that of the designed bridge life. So it is important to pay attention to the U-ribs of the slow lane.