大跨径斜拉桥钢结构疲劳监测与评估

Fatigue Monitoring and Evaluation of Steel Structure of Long-span Cable-stayed Bridge

以某大跨径斜拉桥为研究背景,基于钢箱梁的定期检测结果,研究了该斜拉桥的钢结构疲劳性能。在疲劳开裂较严重的顶板与U肋焊接细节、关键受力部位的底板与U肋焊接细节、索梁锚固区焊接细节布置传感器,测试各主要焊接细节的疲劳应力历程,基于雨流计数法获得疲劳应力谱。分析结果表明:苏通大桥目前的交通流量远大于2010年前的交通流量;钢箱梁底板与U肋焊接细节、索梁锚固区锚固板与外腹板焊接细节的疲劳寿命评估结果大于设计使用年限;若不计焊接初始缺陷与焊接残余应力,顶板与U肋焊接细节不会过早地发生疲劳破坏。

Taking a long-span cable-stayed bridge as the study background,and based on the periodic detection results of steel box girder,the fatigue performance of steel structure of this cable-stayed bridge is studied.Sensors are arranged in the welding details of roof and U-rib,the welding details of bottom plate and U-rib and the welding details of cable beam anchorage area where the fatigue cracks are serious to test the fatigue stress history of each main welding detail.The fatigue stress spectrum is obtained based on the rain flow counting method.The results show that the current traffic flow of Sutong Bridge is much larger than that before 2010.The fatigue life evaluation results of the welding details of steel box girder bottom plate and U-rib,and the welding details of anchor plate and outer web in the anchorage zone of cable girder are larger than the design service life.If the initial welding defects and welding residual stress are not considered,the welding details of top plate and U-rib will not be damaged prematurely.