多室箱梁剪滞效应的变分法分析

Analysis of shear Lag Effect on Multicell Box Girder by Means of Variational Calculus

本文用变分法导出了具有竖向对称轴的由腹板及翼板组成的任意形状薄壁结构(包括多室箱梁)的剪滞效应计算通式,并分别通过单室箱梁,槽型宽梁、多室箱梁等算例进行验证。结果表明,本文解与有限条法,试验分析,三杆法等结果符合良好,且计算简便。最后对现行规范的翼缘有效宽计算公式进行了分析,指出了其局限性,并提出了适应范围广,精度高且计算简便的有效宽比计算公式。

In this paper,the formulas for calculating shear lag effect on arbitrylyshaped thin-walled girder(including multicell box girder)which consistsof web and flange and possesses a vertical symmetry axis in its cross section,are derived by means of variational calculus,and checked by examples ofcalculating shear lag effect on box girder,wide channel beam and multicellbox girder respectively.The calculated results are in good agreement bothwith model test results and with that calculated by either the finite strip method or the three-bar method.Finally,the formulas,used in currentbridge code,for calculating the flange's valid width are analysed and the-ir limitation is indicated by the author.Meanwhile,the more convenientand accurate formulas for calculating the flange's valid width ratio aresuggested.