平板结构中翼缘的负剪力滞效应

NEGATIVE SHEAR LAG IN FLANGE OF PLATED STRUCTURE

箱型截面在对称荷载作用下产生弯曲应力,如果板肋交界处的应力大于横截面上翼板中部的应力,称作“正剪力滞”效应,反之称为“负剪力滞”。翼板中应力不均匀现象主要是由于翼板中剪切变形的影响所致。在设计预应力混凝土箱型截面中。如果剪力滞系数λ值过大,则应采取必要措施防止这种应力集中现象,否则会产生局部开裂或失稳现象。但是如果在结构的横截面上,翼缘中部应力反而大于板肋交界处的弯曲法向应力,这种现象破坏了翼缘板的有效分布宽度的基本概念,这种“负剪力滞”效应更应该值得工程界的普遍关注。在大量的平板结构(如高层建筑的筒中筒结构,桥梁的连续、悬臂体系)中,都不可避免地有负剪力滞效应发生,本文旨在对负剪力滞现象做一些探索和必要的解释。

The negative shear lag phenomenon is not a particularly exceptionalphenomenon but an effect which may occur at a wide variety of structuralarrangement of plated structures. with a considerable degree of significance.A description and explanation of shear lag effect is the main object ofthis paper. There exists three interpretations concerning the negative shearlag: One is due to shear flow magnitude and form, the second is due tothe sign of additional moment caused by shear deformation of top andbottom slab and third reason is due to compatability of deformation.