Construction Scheme for Cable System Installation of Liujiaxia Bridge
The total length of ZD2 contract section of the project is 1.473181km, and the main works include Liujiaxia Yellow River Bridge and bridge approach. Liujiaxia Bridge is a 1-536m single span double hinged simply supported steel truss stiffened girder suspension bridge. The whole bridge is equipped with 4 main cable saddles and 4 splay saddles. The main cable saddles and splay saddle grooves are cast steel. The splay saddle body is an assembly weldment. The whole bridge is equipped with two main cables, each composed of 44 127 wire Ф 5.2mm galvanized high-strength steel wire strands, with the main cable spacing of 15.6m, rise span ratio of 1:11, and mid span sag of 48.7m after completion of the bridge. There are three categories of cable clamps for the whole bridge: ① sling clamp connecting the main cable and the sling, ② hoop clamp for shaping the main cable, and ③ closed clamp for protecting and sealing the main cable saddle and outlet. Due to different sling tension and main cable inclination angle, the required clamping force of sling clamp is different, and the length of sling clamp and the number of screws are different. The sling adopts 73 - φ 5.0mm galvanized high-strength parallel steel wire bundle and hot extruded color PE sheath. The whole bridge is equipped with 65 pairs of parallel vertical slings, with a standard spacing of 8m. The end slings are 12m away from the center line between the bridge towers, and there are no slings on the side span. The upper end of the sling is provided with a pin type lifting lug to connect with the cable clamp, and the lower end is provided with an anchor head to connect with the anchor box on the top of the stiffening beam. An adjustment of ± 100mm is set at the lower end of the anchor head. In order to meet the needs of lateral deformation of slings, 17 pairs of shorter slings in the middle of the bridge span are equipped with a spherical rotation device at the upper end of the suspender. In order to limit the longitudinal horizontal displacement of the main cable and stiffening beam, two groups of flexible central buckles are set in the middle of the span. The central buckles are of the same specification as the slings, and 200KN pretension is applied during installation.
