不同截面形式下箱梁剪力滞效应分析

Analysis of shear lag effect of box girder under different section forms

为研究不同截面形式下箱梁剪力滞效应,以剪力滞效应典型解析法为基础,推导了不同截面形式(截面高度或截面顶底板厚度不同)下箱梁剪力滞附加弯矩计算公式。对一箱梁算例,分析了截面形式变化对箱梁剪力滞效应的影响程度。结果表明,截面形式变化对箱梁剪力滞效应有一定的影响,随着截面高度(顶底板厚度)的减小,剪力滞附加弯矩沿跨中向两支座方面变化幅度逐渐增大,剪力滞附加挠度占箱梁总挠度的比例逐渐增大;集中荷载和均布荷载下,截面高度越小,剪力滞系数在面内分布越均匀(剪力滞效应越小),而截面顶底板厚度越小,剪力滞系数在面内分布越不均匀(剪力滞效应越突出)。

In order to study the shear lag effect of box girder in different section forms,the calculation formula of additional moment of shear lag of box girder in different section forms(different height of section or thickness of section top and bottom)is derived on the basis of typical analytical method of shear lag effect.For a box girder,the influence of the change of section form on the shear lag effect is analyzed.The results show that the shear lag effect of box girder is affected by the change of section form.With the decrease of section height(thickness of top and bottom plate),the shear lag additional bending moment gradually increases along the mid-span direction of the two supports,and the ratio of the shear lag additional deflection to the total deflection of the box girder gradually increases;under concentrated and uniformly distributed loads,the smaller the section height,the more uniform the shear lag coefficient is distributed in the plane(the smaller the shear lag effect),the smaller the top and bottom plate thickness of the section,the more uneven the distribution of the shear lag coefficient in the plane(the greater the shear lag effect).prominent.