Research On Shear Lag Effect In Steel Box Girder Of Single Plane Cable-stayed Bridge

In this thesis, the achievement of theoretical and experimental study on shear lag effectof thin-walled steel box girder was introduced. Then considering the characteristics of thesingle plane cable-stayed bridge with steel box girder, the analytical method and thenumerical method were compared and discussed thoroughly. Taking Daxie Second Bridge inNingbo as an example, the result derived from finite element method model was testified byactual measurement data on site to analyze the shear lag effect in main girder of the bridge.The main conclusions are as follows: Firstly, shear lag effect in steel box girder of singleplane cable-stayed bridge is very complicated. By the comparison between energy variationmethod and bar simulation method, the author regard the second method is simpler in solutionprocedure. And through comparing the calculation result of three bar simulation method andsimulation of shell-beam composite model, it proved that the bar simulation method is alsoqualified in precision. Therefore it is a practical calculation method. Secondly, the parameteranalysis indicated that the size and shape of closed-loop stiffening ribs have effect on theshear capacity and the displacement function of flange plate to a certain extent. When thethickness and height of stiffening ribs increased or the space between the ribs decreased, theshear lag effect was reduced. Thirdly, the effective width of flange plate can be affected bystayed-cable force, for example, the effective width was reduced by22%in the main girder ofDaxie Second Bridge. Fourthly, stress test was carried out through the whole constructionstage of Daxie Second Bridge. In this article, by analyzing the test data in the largestcantilever construction stage, the installation of the pavement and ancillary facilities stage andthe load test, the result from finite element method model with same structural system andloading condition was compared. At last, the precision of FEM modeling was provedaccurate.