翼板横向位移对箱梁剪力滞效应的影响

Influence of lateral displacement of flanges on shear lag effect of box girder

为了揭示翼板横向位移对箱梁剪力滞效应的影响,在箱梁全截面上引入能充分反映剪力滞翘曲特性的中性轴修正系数,选取剪力滞效应引起的附加挠度为广义位移,从翼板剪切变形与附加挠度的几何关系入手,定义了箱梁的翼板横向位移模式,运用能量变分法建立了考虑翼板横向位移影响的箱梁剪力滞效应解析理论.简支和连续箱梁算例分析表明:考虑翼板横向位移的计算结果与有限元数值解吻合更好,进而验证了所提方法的正确性;翼板横向位移对箱梁剪力滞效应有一定的削弱作用,其对附加挠度的影响远大于剪力滞系数;与不考虑翼板横向位移的计算结果相比,考虑后简支和连续箱梁跨中截面顶板肋处的剪力滞系数减小了7.88%和6.81%,跨中截面附加挠度减小了61.81%和71.08%.

To reveal the influence of lateral displacement of flanges on the shear lag effect of box girder, the neutral axis correction coefficient which can fully reflect the shear lag and warpage characteristics was introduced into the full section of box girder, the additional deflection induced by shear lag effect was chosen as generalized displacement. Based on the geometric relationship between flange shear deformation and additional deflection, the lateral displacement mode of flanges of box girder was defined. The analytical theory of the shear lag effect of box girder considering the influence of lateral displacement of flanges was established by the energy variational method. Examples of simply supported and continuous box girders show that the calculation results considering the lateral displacement of the flanges are in better agreement with the finite element numerical solution, which verifies the correctness of the proposed method. The lateral displacement of flanges weakens the shear lag effect of box girder, and its influence on the additional deflection is much greater than that of the shear lag coefficient. Compared with the results without considering the lateral displacement, the shear lag coefficient of the intersection of the top plate and web is reduced by 7.88% and 6.81% at the mid-span cross section of simply supported and continuous box girder, and the additional deflection is reduced by 61.81% and 71.08%.