Overall Design of 48 m/1 600 t Through Overhead Launching Gantry for Construction of a High-Speed Railway Bridge

The precast segments of the 48-m span simply-supported box girders of Jinshan Huanghe River Bridge on Datong-Xi′an Passenger Dedicated Railway were erected by the through overhead launching gantry.The gantry is mainly composed of the principal structures(the main frame and launching nose),main supports(the front,middle and rear support legs),brackets,trolley shifting mechanism,segment support cross beams,hoisting system,wet joint external formwork,girder carrier system,hydraulic system and electric system,of which the main frame of the gantry is the construction load carrying structure.The models for the gantry were set up by the ANSYS,the force conditions,deformation of the gantry and the force conditions of the pier-side brackets under the load cases of loading on a full span,the longest cantilever of the launching nose and shifting of the support legs and traveling of the gantry to next span were analyzed.The results of the analysis show that the force conditions and deflection deformation of different components of the gantry can satisfy the requirements for service.