基于预应力扩散的变截面箱梁剪应力计算方法

Shear Stress Calculation Method of Box Girder with Variable Section Based on Prestress Diffusion

文中在变截面箱梁剪应力计算传统方法的基础上,考虑轴力变化产生的附加剪应力,并提出预应力扩散的概念,引入预应力扩散函数,运用楔形弹性体理论求解,建立了基于预应力的扩散的变截面箱梁剪应力计算方法.以某特大桥中跨悬浇段为例,对比使用传统计算方法和本文计算方法的计算结果发现:在根部附近轴力变化对剪应力影响很大,在悬臂自由端附近影响较小;在施工阶段中传统计算方法会大大低估截面中的剪应力和主拉应力,因此不能忽略轴力变化对剪应力的影响.

Based on the traditional calculation method of shear stress of box girder with variable cross section,the concept of prestress diffusion was put forward by considering the additional shear stress caused by the change of axial force.By introducing the prestress diffusion function and solving it by using the wedge elastic body theory,the calculation method of shear stress of variable cross-section box girder based on prestress diffusion was established.Taking the mid-span cantilever casting section of a super-large bridge as an example,the comparison between the traditional calculation method and the calculation method in this paper shows that the change of axial force has great influence on the shear stress near the root,but little influence near the free end of the cantilever.In the construction stage,the traditional calculation method will greatly underestimate the shear stress and principal tensile stress in the section,so the influence of axial force change on shear stress cannot be ignored.