薄壁箱梁剪力滞效应的有限梁段分析

Analysis of Finite Beam Segment Concerning Shear Lag Effect of Thin-walled Box Girder

采用基于翼板剪切变形规律而定义的翘曲位移函数,通过有限梁段法来研究薄壁箱梁的剪力滞效应。取薄壁箱梁剪滞基本微分方程的齐次解作为梁段单元的有限元位移模式,在能量变分法的基础上,导出相应梁段单元的刚度矩阵和荷载矩阵。通过分析简支梁和悬臂梁2种不同边界形式的箱梁,计算其在均布荷载和集中荷载作用下的挠度和纵向应力,并与相应的变分法的计算结果对比,结果吻合良好,验证了本文方法的准确性和可靠性。计算结果表明,剪力滞效应对薄壁箱梁纵向应力的影响是显著的。

The shear lag effect of thin-walled box girder was studied by the finite beam segment method based on thewarping displacement function defined by the flange plate shear deformation law.The homogeneous solution of the basicdifferential equation of thin-walled box girder was taken as the finite element displacement mode of the beam element.Based on the energy variational method,the stiffness matrix and the load matrix of the corresponding beam element werederived.By analyzing the box girder with two different boundary forms of simply supported beam and cantilever beam,the deflection and longitudinal stress under the uniform load and concentrated load were compared with thecorresponding variational calculation results.The results are in good agreement,which verifies the accuracy andreliability of this method.The calculation results show that the influence of shear lag effect on the longitudinal stress ofthin-walled box girder is significant.