Warping Displacement Model Study For Shear Lag Efect In Thin-walled Box Girders

Box section structure with light, bending stiffness big wrest resistant characteristics, so in bridge structure be widely adopted. In the symmetrical bending existing box shear lag phenomenon, if disregard this phenomenon will underestimate the actual stress produced box beam structure, make structure is not safe. Thin-wall box girder shear lag effect as a classic subject, in the bridge structure design and analysis should not be ignored. Reisser hypothesis wing warping displacement along the lateral longitudinal function for second-degree parabola distribution, with the principle of minimum potential energy biaxial analysis symmetric rectangular section box girders of shear lag effect. This paper put forward the original literature in the shear lag warping displacement function, and on the basis of cantilever for thin-walled box girder, and to meet the axial force on the basis of a balance, in warping displacement function expression of and complements to fix.This paper mainly from the following aspects research:1. Based on the comprehensive consideration of the traditional shear lag warping displacement mode and included in the warp stress of the conditions of the balance on the basis of the model of correction is derived, and the cantilever box girder box girders respectively in concentrated loading, uniformly distributed load stress formula and deflection formula. Through numerical example, calculates the box girders and cantilever box girders of stress, and analysis of the shear lag effect of improving the degree of box girder deflection;2. Clearly define the box beam shear lag effect analysis and shear lag generalized displacement ζ corresponding generalized force, namely cut moment.when M ζ, and derived by using generalized force (internal force) calculation formula of the stress.3. Detailed in the concrete is concentrated load and uniformly distributed load, simply supported and cantilever beam stress formula, and comparison;4. To shear lag warping displacement function take a quadratic function, three times of function, four function and cosine functions, all kinds of stress and that that the stress and ansys modeling results are compared, and draw some conclusions;5. Considering the shear lag effect of supporting, in the section take different size supporting, draw all kinds of stress contrast diagram and the shear lag coefficient contrast figure.