Geometric Nonlinear Analysis Of Long Span Single Plane Cable Stayed Bridge

In recent decades, with the development of bridge technology, appearance of new material and great progress in design and construction, cable-stayed bridges, by their beautiful shapes and unique structural qualities, have entered into their summit of construction in the world. Single plane cable stayed bridges have been more and more accepted by the bridge engineers. The non-linearity of the structure will bring qualitative change with the span development of the quantitative change, and be more and more important in the process of the design and the construction. As there is only one central plane in the single plane cable stayed bridge, and the stress of the cable is bigger than the double-cable, so the behaviour of the non-linearity should be paid more attention to the single plane cable stayed bridge.The basic theory of the non-linearity of the cable-stayed bridge is firstly introduced in this thesis, then three principal factors that affect the geometric nonlinearity of cable-stayed bridges are described, which are cable sag effect, large displacement effect and the coupled beam-column effect of bending moment and axial force. After that the finite element analysis method for the non-linearity of the cable-stayed bridges was introduced, which namely the equivalent modulus of elasticity, introducing stability functions and continuously modifying geometry of structure. With the help of FEM-soft ware of MIDAS/Civil, the modeling of Zhengzhou cable-stayed bridge with single plane was made, which has 146 construction phrases, and then the linearity and the non-linearity were investigatied, the key points and positions were selected for the main research, there are four construction phases which are selected for the emphasis analysis, the four phases are separately pre-closing of side-span, closing of side span, pre-closing of mid-span and the closing of the mid-span, as well as the finished phrase of the cable-stayed bridge which are acted by the secondary dead load and the live load. Every phrase is analysed by five loading cases, which contains linear analysis, three non-linear factors effect alone and the total effect together. The linear and non-linear analysis of all loading cases in constructing stage and finished stage are made. According to the comparison between those results, some valuable conclusions are obtained for reference in design of the same type cable stayed bridges.