简支及悬臂箱梁在角隅轴向荷载作用下的翼板纵向应力

基于能量变分原理，拟定轴向荷载作用下箱梁的纵向位移函数，得到关于翼板剪切变形引起的位移差函数的基本微分方程，继而推导出箱梁翼板纵向应力表达式，并首次得出角隅轴向荷载作用下翼板出现应力不均匀分布的荷载及边界条件。通过对一模型箱梁进行计算，并与通用有限元软件ANSYS壳单元计算结果进行比较，验证了该方法和所推导公式的正确性。研究结果表明，当作用于简支箱梁截面角隅处的轴向荷载（合力无偏心）为集中或分布荷载时，翼板不产生纵向应力不均匀现象；当作用于悬臂箱梁截面角隅处的轴向荷载（合力无偏心）为集中荷载时，翼板不产生纵向应力不均匀现象，而当荷载轴向分布时，翼板将产生纵向应力不均匀现象。实际工程中，横力弯曲使悬臂箱梁产生剪力滞效应，这种效应会与轴向分布荷载产生的效应叠加，设计时对此应予以充分考虑。

Longitudinal stresses in flange plate of simple-supported and cantilever box girder with axial load acting on the section corners

Based on the theory of variational energy principles and assumed longitudinal displacement functions of a box girder under axial loads,the basic differential equation of the displacement difference function caused by the shear deformation of its flange plate is derived.Then the longitudinal stress expression of the flange plate can be deduced.For the first time,the load formulas and boundary conditions resulting in the non-uniform stress distribution of the box girder flange plate under axial loads are obtained.Stresses calculated on a box girder model are in good agreement with those obtained by the numerical results from ANSYS,which validates the presented method and formulas.There are not uneven longitudinal stresses in the flange plate when a concentrated or distributed axial load(combined force without eccentricity)acting on the corner of the simple-supported box girder.There also exist no uneven longitudinal stresses when a concentrated axial load(combined force without eccentricity)acting on the cross section corner of cantilever box girder.However,non-uniform longitudinal stresses still non-uniform phenomenon will exist in the flange plate when the load is axially distributed.In practical engineering,shear lag effect exists in a cantilever box girder with vertical loading,and it will be combined with the effect of axially distributed loads,which should be given full consideration in design of the box girders.