General Conception And Mechanics Behavior Analysis Of PC Cable-stayed Bridge With Three Towers

With storage in the reservoir area of Three Gorges being finished progressively, the surface of Yangtse River is widen day by day and the shipping condition in this district has got a great improvement, but more harsh requisition for the scale of bridges that span Yangtse River challenges engineers in the future. Multispan cable-stayed bridges with the advantage of spanning must be a main bridge type that is studied by engineers.This text is based on multispan cable-stayed bridge scheme in Zhongxian County, because middle tower without stiffening cable will bring great deformation under asymmetric live load etc, It begins with the concept design of multispan cable-stayed bridge and takes qualitatively analyze referring mechanics action under different ratio between middle span and side span, different connection among tower, beam and pier, external stiffening methods.It regards qualitative analysis as guidelines and carries on quantitative analysis, because some parameters in FEM will be changed frequently, I get support from Ansys which is a famous macros finite element program, Matlab named matrix laboratory and APDL language to make some simple redevelopments, such as building modal, moving load, load combination and so on. After analyzing the data, I think the floating system with overlapping cables can effectively solves the rigidity problem for multispan cable-stayed bridges when assistant piers are not suitable for them.The text analyses the reasonable dead state of floating system with overlapping cables finally. It confirms the initial dead state by minimum bending energy method at first, then decides the reasonable prestress quantity and the reasonable dead moment region by the stress balancing method. At last, the reasonable finished dead state of the total structure is determined by influence matrix method and least square method, this state comprehensively considers the cable forces, moment of the main beam and towers etc. Because the finished dead moment of main beam falls into the reasonable dead moment region, it proves the rationality of floating system with overlapping cables.