English：

As the main bridge type of urban bridges, steel box girder bridges are usually constructed byfactory prefabrication and on-site hoisting and welding. During the welding process, the deformation ofsteel due to rapid heating and cooling may lead to uneven bridge deck and stress concentration in thedistortion area. In order to improve the welding quality and post-weld working performance of the buttweld of steel box girder, a steel box girder bridge in a citywas taken as the research object, and thedouble ellipsoid heat source model was used to simulate the finite element welding process. The influenceof the welding sequence of the circumferential seam for the steel box girder assembly on the stress anddeformation of the structure was analyzed, and the optimal sequence of the circumferential seam weldingwas proposed. The results show that different welding sequences have little effect on the verticaldeformation of the steel box girder roof, but have a significant effect on the welding residual stress.Optimizing the welding sequence can significantly improve the welding residual stress of the top plate andthe bottom plate, and the residual stress of the top plate is obviously smaller than that of the bottom plate.The comprehensive analysis shows that the optimal welding sequence is first bottom plate, then web, andfinally top plate. After the prioritywelding of floor to form a whole, the restraint effect of the web on theroof can be enhanced, thereby reducing the vertical displacement change caused bywelding.