Spatial Stress Analysis Of Steel Box Girder For Long-Span Cable-Stayed Bridges

There has been a rapid development of cable-stayed bridge since 1990s in China. Many world-class span cable-stayed bridges are built and the steel box girder with orthotropic plates which are suitable for this system is widely applied. But the steel box of this form is not fully mature and a series of issues about design, manufacture, installation need further study. Taking the Edong Yangtze River Highway Bridge (hereinafter referred to as Edong Bridge) as engineering background, the following three aspects are studied in detail in this thesis:(1) The equivalent treatment for the elastic support by the cable of Edong Bridge is taken and the fine finite element model of 5 standard steel box girder segments is established by using ANSYS. Two kinds of load cases are calculated and the most unfavorable position of vehicle load is confirmed by comparison. This method can save a lot of workload and the spatial stress of steel box girder can be accurate simulated.(2) Basing on the established finite element model 5 different arrangements of U rib on top plate including the original design of steel box girder of Edong Bridge are selected and calculated. By the comparative analysis for the stress on the control section the corresponding spatial stress distribution of the stiffened plates and U rib is obtained. The results show that the original design layout of U rib by 600mm spaced is the best situation among the 5 selected arrangements of U rib.(3) The study on the diaphragm spacing is carried out to analyse the influence on spatial distribution of bending stress and warping stress of steel box girder under eccentric live load.6 arrangements of diaphragm of different interval distances including the original design are selected and calculated. The results show that the bending stress caused by eccentric load will be able to meet the engineering requirements by setting a diaphragm, and the torsion and distortion effects can be controlled within a relatively small range by setting 3 diaphragms.