Optimized wind-induced stability assessment for steel box girder bridges during incremental launching: a wind-friction coupling approach

Abstract During the jacking construction process of long-span steel box girder bridges, the structural system does not form a whole, and the risks of slip and overturning under wind loading significantly increase. The establishment of scientific and reasonable stability assessment and control methods is urgently needed. In this study, with the Baisha interconnection bridge as the background, on the basis of 3D finite element analysis and static wind three-component force theory, force response and wind-induced stability analyses of the structure under different typical work conditions during the jacking process were systematically carried out. Through overall modeling and segmental loading of the guide beam, main beam and temporary support, the stress concentration area and displacement extreme points of the structure in the cantilever state were identified. Studies have shown that the cantilever stage of the guide beam at 60 m is the most unfavorable working condition for the structure, with a maximum deflection of 434 mm and an equivalent stress of the main girder of up to 155 MPa, which is close to the design limit. A wind load–friction coupling model was established, and the critical wind speeds for the start-up of the structure and instability were determined to be 36.4 m s −1 and 51.5 m s −1 , respectively. The longitudinal overturning analysis revealed that the structure had sufficient moment resistance, and the safety factor reached 2.41. A staged response mechanism of the construction wind speed and a lateral limiting strategy are proposed, and a closed-loop control system of wind-induced stability is constructed on the basis of the reaction force, wind speed and deflection. The research results can provide a theoretical basis and engineering guidance for wind stability assessment and safety decision-making during the jacking construction period of long-span steel box girder bridges.