Analysis Of Vertical Rotation Construction And Suspenders’Tension Sequence For Large Span Single-rib Arch Bridge

Gangou Bridge is the longest through type single-rib arch bridge within China with a main span of250m. Steel arch-ribs with large tonnage should be assembled and united with vertical-rotation lifting method. Large-scale gantry framework which is higher than50m assembled by universal members is used in this construction. Security and stability of the rotation system and gantry framework is particularly important and must be calculated and analyzed in order to ensure the construction process smoothly. A reasonable sequence and tension of the stretching suspenders is a key factor to safety of arch bridge.Finite element model of the Gangou Bridge and Gantry Framework are implemented in this paper to ensure the whole vertical rotation construction process safe and unstressed state method is successfully applied to the hanger tension construction process of this bridge. The details are specified as followed:Firstly, the outline of the arch construction procedures is introduced. The whole rotation and arch closure process is simulated by the FEA model. A reasonable scheme for pre-turaing construction is advanced. The function expression of the dragline force on rotation angle is deduced in order to get the most unfavorable processing condition for the overall calculation. The removal sequence of the temporary tie bar is also discussed in this paper. There is no doubt that the stability of the arch rib during the construction process is dependable with the analysis of the FEA.Secondly, a reasonable optimized assembling scheme for gantry framework is suggested in this paper. To establish the space finite element model of the gantry, the paper analyzes the static and stability of it and gives influence of guy-cable on the gantry. It says that gantry framework has to be reinforced because the axial force of upright column is very close to admissible value though buckling safety factor of gantry framework is between6and7. Tension of a single steel pre-stressed anchorage cable is suggested to be40kN and the angle of wind cable would be reasonable to be40to45degree.Finally, the finite element method is applied to the whole bridge to analyze rational cable force, sequence and tension of suspenders. The rational cable force and a reasonable stretching plan are introduced in this paper respectively with the minimum bending energy method and unstressed state method.