Shear Lag Effect Analysis Of The Wide Flange Thin-walled Structure

Thin-walled structure has good overall structure of the performance, so especiallyin the civil engineering is widely used in bridge engineering; thin-walled structure isgenerally divided into the open section and closed section type, under symmetrical load,considered the shear deformation and found that thin-walled structure existed shear lagphenomenon; and ignored the shear lag effect could seriously affect the safety of thestructure. At present, domestic and foreign scholars on the study of shear lag and made apart of the results, but there are still many problems to be solved. This article obtainsfrom the angle of energy functional variation principle, study the shear lag effect ofdouble T beam, I beam and Single box single chamber box girder the influence of thestatic and dynamic characteristics of box girder, it has important practical significance,this paper mainly do the following work:①Introduce the basic concept of shear lag and shear lag effect in thin-walledstructure at home and abroad are summarized in detail the static and dynamic aspects ofthe research status quo, limitations and applicability of various theories and methods arereviewed, and further puts forward the need to be addressed and shear lag research fieldblank.②Double T beam shear lag effect of the static and dynamic characteristics analysis:Based on energy variation principle, the introduction of shear lag effect caused by thewing plate shear deformation according to mechanism of the basic definition of awarping displacement function, derived considering shear lag effect of the double Tthin-walled beam static differential equations and natural boundary conditions; workedout the shear lag effect of the natural frequency of vibration of analytic solution; andsimply supported beam and cantilever beam under different load cases of stress anddeflection calculation expression, and then through a numerical simulation of thenumerical example to verify the correctness of this algorithm; Secondly on the basis ofthe shear lag effect of static analysis, application of Hamilton’s principle is deduceddouble T thin-walled beam power differential control equations and natural boundarycondition, and considering the shear lag effect of simply supported T beam naturalfrequency of vibration analytical solutions, a detailed analysis of various parameters onthe natural frequency of vibration reduction factor and the influence of shear lag effectof the impact on the natural frequency of vibration. ③Thin-walled straight line cross section I beam shear lag analysis: This paperintroduced double warping displacement function, derived the thin-walled I-beam staticdifferential control equations and natural boundary condition, through the analysis ofthe system, obtain I beam shear lag static characteristics.④The static and dynamic analysis of thin-walled box beam shear lag effect: On thebasis of previous analysis of single box single chamber box girder using the energyvariational method, put forward considering the influence of the prestressed steel tendonand the shear deformation power, set up energy equation and conclude that differentialcontrol equation of the static and dynamic and natural natural boundary conditions, anddeduce the stress, shear lag coefficient of simply supported beam and cantilever beamand deflection calculation formula of static and dynamic differential equation solution.⑤Project instance analysis: with Lan-xin second line shu-le river extra largebridge as engineering background, firstly established the CSB software two dimensionalmodel, the construction phase of section stress has carried on the analysis of the system;Secondly established ANSYS finite element model, analyzed the following aspects ofresearch: the largest cantilever stage box girder longitudinal and transverse shear laganalysis; Full bridge phase under the working condition of three kinds of combinationbox girder longitudinal shear lag analysis of the working condition of combination oftwo and three box girder, transverse shear lag analysis provides a reference for practicalengineering.