Three Dimensional Stress Analysis Of Main Girder With Twin-Box Cross Section Used In Cable-Stayed Bridge

The three dimensional finite element stress analyses of main girder with twin-box cross section used commonly in cable-stayed bridge have been carried out. By using the structural analysis program ANSYS,seven finite elements models based on three long-span cable-stayed bridges' box girder with different lengths and dimensions have been built up,and the triaxial stress of them are analyzed. In order to considering the affections of the adjacent zone out of the girdler section,the internal-forces of two end surface which were obtained by the horizontal shaft system analysis are exerted on each model respectively. Moreover,the weight,cable force and prestressing forces including girder longitudinal,diaphragm transverse and inclined web vertical directions are considered. Based on the above,the three dimensional stress of the box girder with different dimensions are analyzed.By analyzing the result of above seven working situation,some conclusions are given out. The main tensile stress of in diaphragm is very large. In addition,the main stress at the interface of the bottom flange and inclined web,which located at the interface with the diaphragm,is the largest. So,it should be taken more attention to them in design. Analysis could also show,to improve the stress distribution of the twin-box single cross section of cable-stayed bridge,it is the best way by thickening the bottom flange.