单箱双室箱梁的剪力滞效应分析

ANALYSIS OF SHEAR LAG EFFECT OF TWIN-CELL BOX GIRDERS

针对单箱双室箱梁,考虑各翼板间剪力滞翘曲的差异,并结合全截面轴力自平衡条件,定义了箱梁各翼板的剪滞翘曲位移函数.利用最小势能原理,建立了双室箱梁考虑剪力滞效应的控制微分方程.对一典型的单箱双室简支箱梁,利用空间板壳数值方法和本文解析解方法,研究了满跨均布载荷和跨中集中力作用下截面的剪力滞分布规律.结果表明,本文提出的剪力滞翘曲位移模式能够反映双室箱梁各翼板间剪力滞翘曲的差异,本文解析解与有限元数值解吻合良好.双室箱梁中腹板部位顶、底板处的剪力滞效应与边腹板部位有一定差异,对算例结构,中腹板部位的顶、底板应力小于边腹板部位的应力.

For a twin-cell box girder, from the difference of the shear lag warping between different cantilever plates, and combined with the axial force equilibrium condition of the whole section, a new shear-lag warping displacement function is defined for each cantilever plate of the box girder. The governing differential equations of equilibrium for the shear lag for the twin-cell box girder are established on the basis of the variational principle. For a typical simply supported beam with a twin-cell box girder, using three dimensional numerical methods of the plate-shell element and the analytical solution method proposed in this paper, respectively, the shear lag distributions under the uniform load and the concentrated force are obtained. It is shown that the new displacement pattern of the shear lag warping can reflect the difference of the shear lag warping between different cantilever plates and the new analytical solutions are in good agreement with the finite Element results. The shear lag effect on the top and bottom plates near the middle webs is different from that near the side webs on the twin-cell box girders. For an example girder, the stresses near the middle webs are larger than those near the side webs