Hoisting and Installation Construction Technology for Main Cable Saddle of Nizhou Waterway Bridge of Second Humen Bridge

The Nizhou Waterway Bridge of the Second Humen Bridge is an asymmetrical double-tower steel box girder suspension bridge with the main span of 1 688 m. The bridge consists of four main cable saddles, and the main cable saddles have a structure of cast welding that consists of two semi-saddles locked by high-strength bolts. The semi-saddles with the weight of 125 t are installed in the main saddle chamber at the top of a 256.4 m-high tower. The main cable saddles are hoisted by means of transfer platform on the top of bridge pylon cap + support by portal frame on pylon top + vertical hoist by a hydraulic jack with continuous lifting + longitudinal translation by transporter. During the construction, the grid reaction frame is hoisted by a hoisting system on the tower top, and concrete grout is poured into the grid reaction frame after being precisely positioned; then the upper and lower supporting plates are hoisted by the hoisting system on the tower top; finally, two semi-saddles are hoisted to the top of the tower by the hoisting system on the tower top and joined together by the high-strength bolts. During the installation of the superstructure of the main bridge, according to the pre-deflection monitoring instructions, the main saddles are gradually pushed in place by two 1 000 t jacks, thus final positioning and installation of the main saddles are completed. © 2018, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.