The Research On The Design Parameters Optimization For Cable-stayed Arch Bridge

The 4^th Xiangtan bridge is completely new type of structure,which is called flying-bird style,cable stayed tied concrete-filled steel tube arch bridge. It is the only cable-stayed arch bridge directly - the 4^th Xiangtan bridge in which the cables act on the arch ribs in the world. Therefore, research focusing on such bridge is really rare. As a background of the 4^th Xiangtan bridge, this thesis will study on its structural rationality from the following aspects:1. Calculating the arch axis equation of the 4^th Xiangtan bridge by using cubic spine interpolation function, and meanwhile, using finite element method to analyze this arch axis equation and the designed one which is formed by the design of arch axis equation to get the main arch's arch axis bending moment, then by comparing them to get a less bending moment arch axis equation as the 4^th Xiangtan bridge's rational arch axis line.2. Study the rationality of the structural characteristics of the 4^th Xiangtan bridge considering from the side span and main span's ratio,the effective height of main tower ,the rise-span ratio,the structural stiffness etc. aspects,the rationality of the structural system of the bridge is discussed. The paper emphasis on the study of the maily force component of stiffness ratio and bearing load efficiency of main arch,side arch,main tower etc., and points out the optimal approach of component stiffness.3. Comparing the differences of the charateristics of cable forces adjustment between this bridge and those general cable-stayed bridges in the process of adjusting cable of the 4^th Xiangtan bridge. The optimal forces of the cables were adjusted by the method of inter-cable influence matix combined with main arch bending moment influence line by single cable force. The effect of optimization is checked by the FE model.The paper discuss the influence on the mechanic behavior of the whole structure under the final dead load,by analysising several important design parameters of the 4^th Xiangtan bridge, such as main arch axis,side span and main span ratio,effective height of main tower,rise-span ratio,structure stiffness and the stayed cable force influence of whole structure forcing status under constant load after completed bridge, and some suggestions about the rational structure setting are put forward.