Shear Lag Effect Of Composite Curved Beams With Corrugated Steel Webs

The composite curved box girder with corrugated steel webs is a new type ofsteel-concrete structure，use external prestressing technology.Making full use of theadvantages of high shearing-resisting ability of corrugated steel webs and highcompressive strength of concrete，this type bridge has an evident reduction in its gravity.Firstly, based on theory of the ordinary thin-walled box girder, combing the structuralproperties of the composite curved girder with corrugated steel webs, according to thecurved beam theory, thin-walled structural theory, and the variational principal of energyfunction, presuming three shear lag warping displacement functions of the top, bottom andcantilever, respectively, together with the minimum potential principle, the total potentialfunction are established. The elastic differential controlling equations of the bridge arededuced relating bending, shearing, and twisting coupling, and the boundary conditionexpressions are given also at the same time.Secondly, assuming the curvature tends to infinity, the controlling equations and theircorresponding boundary conditions derived previously are changed to equations andboundary conditions for straight girders. This indicates that the equations and boundaryconditions for curved beams are correct and effective.Thirdly, the variational laws for the shear lag and the formula are obtained under theaccumulative load and the uniformly distributed loads respectively.By finite element analysis, the effect of the distribution law of shear lag of the boxgirders with corrugated steel webs analyzed by the geometric parameters in the case ofcurvature tends to infinity and the curved beam into a straight beam. Summed up the mainimpact geometric parameters for the shear lag and the load type, concrete thickness andthe other factors to the effect of the shear lag of the box girders are analyzed.