Study On Shear Lag Effect In Ⅱ Shape Girder Of Double Cable Plane Cable-stayed Bridge With Single Tower

The improvement and development of cable-stayed bridge design theory make the more and more ceble-stayed bridge has been built,and the span more and more large.The main girder of cable-stayed bridge is more and more slender and towards in the thinner and wider development.For the thin and wide beam cross section,shear lag effect is obvious,if in the process of design and construction control ignore the effect of shear lag may cause accidents,therefore,the research of shear lag effect brought to the attention of the countries.The separated beam-and-slab decks are used widely in the large span prestresed concrete cable-stayed bridge.In this paper,the overseas and domestic research status and research methods of the study of the shear lag effect are reviewed.On this basis,considering the research about shear lag effect on Ⅱ-type cross section girder,especially the Ⅱ-type cross section girder used in single tower cablestayed bridge is rarely,combining with the project of Jiang You Fu Jiang cable-stayed bridge,this thesis using finite element method studies shear lag effect of the cablestayed bridge with Ⅱ-type cross section and offers suggestion to the other project.The main contents are the following several aspects:(1)Combining previous research results,comparing the existing analyzing methods of shear lag can be used for double ribbed main beam,such as energy variational method,finite segment method,analytical method and transfer matrix method,and has carried on the analysis and comparison,it is concluded that finite element method is the best analyzing method,because of its advantages of the high precision and visual results.(2)Combination of Jiang You Fu Jiang cable-stayed bridge(its main girder is wide and thin with double ribbed main beam),obtained the double rib girder of single tower cable-stayed bridge is within the scope of the whole bridge shear lag effect distribution rule through the finite element method;The thesis researches the shear lag effects about the Ⅱ-type cross section girders of cabled—stayed bridges under the loads of selfweight,stayed cable,pretensioned force and cradle loads,and gets their the distribution features.(3)The structures of girders which influence the shear lag effects of the single tower cable-stayed bridge with double ribbed main beam are studied.Through to the main girder section set cross slope,longitudinal ribs,different section parameter is analyzed,such as thickness of top plate got under different influence factors and distribution of shear lag effect,provide reference for the design of similar Bridges.