箱形梁布置双层悬臂板时的畸变效应分析

Distortion Effect Analysis of Box Girders with Double-level Cantilever Slab

为了研究双层悬臂板对箱梁畸变效应的影响,在对箱形截面畸变角给出一般定义的基础上,提出一种类似于箱梁约束扭转分析的畸变效应解析法。应用基于最小势能原理的能量变分法,建立双层悬臂板箱梁的畸变控制微分方程及相应边界条件,并通过算例详细分析了下层悬臂板对畸变双力矩、翘曲应力及横截面畸变中心的影响。结果表明:用该解析法计算的畸变翘曲应力与ANSYS壳单元及梁段单元的计算结果均吻合良好;随着下层悬臂板长度的增大,双层悬臂板箱梁的畸变双力矩表现出先增大后减小的变化规律,当下层悬臂板相对长度为1.2时,畸变双力矩达到最大值;双层悬臂板箱梁的角点翘曲应力随下层悬臂板相对长度的增大而减小;当下层悬臂板的相对长度较小时,箱梁截面的畸变中心高于截面形心。

In order to investigate the influence of double-level cantilever slab on distortion effect of box girders,based on the general definition of distortion angle of box section,an analytic method for distortion effect was presented which was similar to restraint torsion analysis of box girders.The governing differential equation and the corresponding boundary condition were established by applying energy variation calculus based on the principle of minimal potential energy.Numerical example was given to analyze the influences of lower cantilever slab on distortion bi-moment,warping stress and distortion centre of the cross section in detail.The result shows that the calculated values of distortion warping stress by using the analytic method are in a good agreement with those by using the shell element in ANSYS and box girder segment element.The distortion bi-moment of the box girder with double-level cantilever slab presents a change law of increasing firstly and then decreasing with the increase of lower cantilever slab length.The distortion bi-moment is maximal when the relative length of lower cantilever slab is 1.2.The warping stress at corner of the box girder with double-level cantilever slab decreases with the increase of the relative length of lower cantilever slab.The distortion centre of cross section of the box girder is higher than the section centre when the relative length of lower cantilever slab is relatively small.