Analysis Of The Shear Lag Effect On â…¡ Shape Girder Of Cable-Stayed Bridge

This paper is based on the theoretical analysis of shear lag effect and combined with the energy variational method of Reissner. The longitudinal displacement of the wing is assumed four parabolic form. Then the theoretical research on the shear lag effect of the∏shaped beam is done, and the calculation formula of the shear lag effect under different boundary conditions are derived. From the results of the study, boundary conditions, load form, girder section, and the width of girder etc have some impact on the shear lag effect of II shaped girder.To explore the shear lag effect on∏shape girder of the cable-stayed bridge in the construction stage and the finished stage, and provide some effective advice to the construction and monitoring of the cable-stayed bridge with∏shape girder, this article is based on the basic theory of finite element method, and uses MIDAS to establish the finite element model of Zhenyuling Bridge which is this paper’s background project, then its distribution law is analyzed. From the results of the analysis, as one or other piece of main girder construction is completed, except NO.0block, the block of main girder construction and their near blocks, the shear lag effect of the middle block changes smoothly, the shear lag coefficient of the finished stage is smaller than which of the construction stage, but the distribution law of shear lag is little changed, the phenomenon of negative shear lag takes place in both the construction stage and the finished stage.At last, this paper is based on the result of theoretical analysis about the shear lag effect of∏shaped girder in this text, and in order to offer a basis for the optimization design of the∏shaped girder of cable-stayed bridge. Finite element method is used to study the influencing factor of shear lag effect on∏shaped girder of cable-stayed bridge which is length of the cantilever plate of wing and thickness of wing. According to the analysis results, with increasing length of cantilever plate of wing, there is a little effects on the vertical distribution of the shear lag effect, and except the end of the main girder and its near blocks, the shear lag coefficients of other blocks are decreased along the cross section of landscape, with increasing thickness of wing, the shear lag effect of vertical distribution and lateral distribution is obvious.