Stiffness Parameters Analysis And Security Research Of Multi-pylon Cable-stayed Bridge

In recent years, with a large number of cable-stayed bridges in our country, Multi-pylon cable-stayed bridge also gradually become a trend. Due to the requirement of the bridge span, the form of the multi-pylon cable-stayed bridge becomes more and more popular. The insufficient stiffness is the biggest problem of multi-pylon cable-stayed bridge. Without enough constraint, the stiffness of main girder and middle towers can not be controlled effectively. As a result, the cables’fatigue stress, the towers’ internal force and the girder’s deflection are larger than conventional cable-stayed bridges. Through innovative thinking, bridge designers put forward a new method that the stiffness of the multi-pylon cable-stayed bridge can be enforced effectively by setting up double row bearings between the girder and towers. According to above analysis, based on the design scheme of multi-pylon cable-stayed bridge, the project of the double row bearings has been calculated and analysed in detail.The main work has been down as follows:①On the basis of the thorough research on documentation, deep analysis of the rigidity of the multi-pylon cable-stayed bridge can be made. On the one hand, compared to the theoretical method of three towers cable-stayed bridge stiffness, the theoretical derivation of four towers and more than four towers cable-stayed bridge stiffness can be made, and the essential differences between them can be discovered.On the other hand, the related regularity can be gotten by summarizing the existing finite element numerical simulation of multi-pylon cable-stayed bridge②Considering the geometry nonlinear effect of the long span cable-stayed bridges, the finite element model has been built in this paper. The influence of the stiffness and security by the double row bearings can be analysed by the influence line of girders displacement and tower’s bottom internal force, the way of force transmission and stability analysis.③By changing the distance between bearings in the multi-pylon cable-stayed bridge mode, the regularity of influence on three parts of multi-pylon cable-stayed bridge (girder, towers, cables) can be analysed. Finally, the reasonable scope of interval distance can be summarized.④By analysing the regularity of influence on the structure of bracket that support the bearings, the reasonable scope of interval distance can be summarized. Then the most reasonable scope of interval distance between bearings can be considered in the general.⑤Although cable-stayed bridges with different towers have different laws on the double row bearings, there are both similarities and differences among the regularity. The multi-pylon cable-stayed bridge structure can be classified numerically. Then the differences on the stiffness of multi-pylon cable-stayed bridge with different towers can be analysed.