Abstract: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.