Residual Stress and Fatigue Strength Analysis of Stiffener Welds of Steel-Plate Composite Girder Bridge Considering Welding Sequence

Welding residual stress will aggravate the fatigue cracking damage of the structure and have an essential impact on the structure's load-bearing capacity. The welding sequence will directly affect the size and distribution of welding residual stress. To this end, this paper establishes a thermal-mechanical sequential indirect-coupling finite-element analysis model, researches the residual stress of steel-plate composite girder bridges considering the welding sequence, and verifies the analysis results through field tests. Then, a three-span steel-plate composite continuous girder bridge was taken as the research object, and the residual stress of the stiffener welds in seven welding sequences was analyzed. On this basis, the equivalent peak-stress method is used to evaluate and predict the fatigue strength of the weld. The research results show that welding residual stresses change the multiaxial stress state of fatigue details. Although under the same external load cyclic stress, the difference in welding sequence directly leads to a significant difference in the equivalent peak stress of the stiffeners, and this difference results in different fatigue properties of the stiffeners. The research results can provide a basis for the welding process and fatigue analysis of stiffener welds in steel-plate composite girder bridges.