Researches On Reasonable Tensile Force And Design Parameters Of Single-Pylon Cable-Stayed Bridge

Cable-stayed bridge is a high-order indeterminate structure. This kind of bridge structure distinguishes itself from any others by that its internal force and line shape can be set by adjusting its cable tensile forces. In the first part of this thesis, many methods used to set the reasonable cable tensile force are introduced and summarized, especially the synthetical method, which is a combination of the minimum bending-energy method and the stress-balance method. By introducing the theory of influence matrix and optimization, a linear programming model for setting the reasonable cable tensile force is established. Based on the methods and model mentioned above, the reasonable cable tensile force in finished state of the Second Banfu Bridge is assigned, and its reliability is verified.In order to study on the static characteristic of the single tower cable-stayed bridge, using the FEM program MIDAS CIVIL, the second part of this thesis gives the static parametric analysis. In this part, the influence of parameters changes on the internal force and displacement is discussed in detail, which includes the slope angle of tower, the stiffness ratio of girder to tower and the length in the non-cables region closed to the abutment of the main span.The last part of this thesis is about the dynamic characteristic analysis of cable-stayed bridge. Theories of dynamic characteristic and numerical methods are introduced; simulations of the cable, the tower and the girder in FEM programming are summed up and compared, and the accuracy of the simulations of the structure's mass and stiffness is discussed; great FEM program MIDAS CIVIL is used for model building and calculating; influences of the cross-beam between the tower poles and the assistant piers on the dynamic characteristic of the whole bridge structure are also analyzed.