Analysis on temporary connection mode of the large-span steel truss girder suspension bridge

During the construction of large-span steel truss girder suspension bridge, the temporary connection between steel truss girder segments has great influences on its construction. Different connection ways may directly affect the real-time and the bridge-completion internal force distributions of truss structure. With the Yangsigang Yangtze river highway bridge project taken as an example, three connection ways, including the gradually hinged method, gradually rigid-connecting method and timely hinged method, were compared and analyzed. The parameters or variables for comparison were the forces, cable force, etc. in steel truss girder member and temporary connection. The research conclusions indicate that, the gradually rigid-connecting method is infeasible because it can't ensure the structural safety, while the gradually hinged method and the timely hinged method can guarantee the structural safety. For the timely hinged method, the work difficulty may be increased as the simulation calculations and the field monitoring analysis are often combined for determining the hinging moment of steel truss girder, and the whole rigidity and stability of structure with the temporary connection measures of the lower chord are better compared to the gradually hinged method. In addition, counterweight was increased appropriately in the girder erection process for making the main cable and girder close to the curve shape of bridge-completion and reducing the forces of the temporary connection. Based on the research of timely hinged method, the timely hinged method without counterweight, the timely hinged method with equal counterweight and the timely hinged method with partial counterweight were compared for analyzing the effects of counterweight on steel truss girder. The research conclusions show that when the timely hinged method with partial counterweight is used, the indicators of truss girder and suspension cable are appropriate. Compared to the timely hinged method without counterweight, the timely hinged method with partial counterweight can close the lower chord into the hinged state in advance, enhancing the stiffness and stability of main girder structure. Compared to the timely hinged method with equal counterweight, the cable force of the timely hinged method with partial counterweight meet the requirements on safety factor, implying that it is an optimal way of temporary connection. © 2020, Editorial Office of China Civil Engineering Journal. All right reserved.