Study On The Feasibility Of Using Curved Approach Bridge As The Fastening And Anchorage Balance System For Steel Tubular Arch Hoisting

In the construction of rib-assembling of deck type concrete-filled steel tubular (CFST) arch bridge, the installation tower is usually replaced with juncture pier, and the unbalanced axial load caused by cables could be transferred to the river banks by approach bridge. This construction method can not only avoid using installation tower but also substantially make use of structure and topographical condition. It has been successfully applied in some projects.In sophisticated relief of mountain areas, the approach bridge is usually designed as curved. But the behavior of curved approach bridge under unbalanced axial load is much more complicated, such as curved approach bridge's bending deformation, wet-joint's crack, stress and displacement of juncture pier out of limit, which would influence the accuracy of rib-assembling.The feasibility of using curved approach bridge as the fastening and anchorage balance system for steel tubular arch hoisting is mainly discussed in this paper, which is a technology item referring to design and construction controlling technology about CFST arch bridge of Hubei communications department. Firstly, a FEM analysis model was built by Midas/Civil, the stress and deformation of bridge decks and bridge piers under different bridge supports were compared, and the feasibility of using curved approach bridge as the fastening and anchorage balance system for steel tubular arch hoisting was verified. Then, considering field engineers' easy calculation, according to principle of minimum potential energy, a simplified curved approach bridge model was built under unbalanced axial load caused by cables, and a method of calculation based on energy principle was suggested. As a result, a calculation formula about vertical and lateral displacement of curved approach bridge was derived, and a MATLAB program was worked out. Finally, combined with the construction practice of Jingyanghe Bridge, a comparison between construction monitoring data and calculating results of energy method and FEM method was carried out; it showed that the calculating results of energy method could meet the engineering accuracy.According to the research it can be seen that: the method of replacing installation tower with juncture pier under conditions of curved approach bridge and using curved approach bridge as the fastening and anchorage balance system for steel tubular arch hoisting is available, which is used in the construction of Jingyanghe Bridge. The method based on energy principle under unbalanced axial load caused by cables is simple and effective, and the results of this method have satisfactory accuracy. All of this can provide reference for similar projects.