剪切变形对箱形梁畸变效应的影响

摘要

为揭示剪切变形对箱形梁畸变效应的影响规律,在合理假设畸变翘曲位移函数和切向位移函数的基础上,应用最小势能原理建立了考虑剪切变形的箱形梁畸变控制微分方程和相应边界条件,并通过数值算例分析了剪切变形及几何参数变化对箱形梁畸变效应的影响.结果表明:考虑剪切变形时的畸变翘曲应力与ANSYS壳单元的计算结果更为接近;与忽略剪切变形时的结果相比,畸变翘曲正应力的降低幅度不超过5%,畸变翘曲剪应力的降低幅度不超过10%;剪切变形对畸变位移的影响很小;随着跨高比的增加,畸变翘曲正应力沿梁跨度的分布曲线由单峰向双峰转变,畸变翘曲剪应力发生正负号改变的截面位置向梁端移动;随着箱壁厚度的减小,畸变翘曲应力显著增大.%In order to reveal the influence of shear deformation on the distortional effect of box girders,based on the assumptions for distortional warping and tangential displacement functions,the distortional governing dif-ferential equations and corresponding boundary conditions of box girders with shear deformation were derived by applying the minimum potential energy principle.A numerical example was used to analyze the influences of shear deformation and geometric parameters on distortional effect of box girders.The research results show that the values of distortional warping stresses with shear deformation are closer to those obtained by using the shell element in ANSYS.Compared with the results without shear deformation,the distortional warping nor-mal stresses with shear deformation decreas by no more than 5%,and the distortional warping shear stresses decrease by no more than 10%.Shear deformation imposes little influence on distortional displacement.With the increase of span to height ratio,the distribution curves of distortional warping normal stresses along the girder span vary from single-peak to twin-peak form and the cross section where the sign of distortional warping shear stresses changes moves towards the ends of the box girder.The distortional warping stresses increase sig-nificantly with the decrease of the wall thickness of the box girder.