Shear transfer between ribbed slab and internal column

The results are presented of tests on 20 micro-concrete wide beam ribbed slabs at internal column locations. It was found that shear failure of a wide beam ribbed slab can occur at an internal column either by punching shear or wide beam shear. Although a punching shear failure of a wide beam ribbed slab is very similar to that of a solid slab, the shear capacity is reduced relatively, because some of the potential shear failure surface is lost when it enters the ribbed section. Plastic theories for punching shear and wide beam shear were developed, which gave good agreement with the test failure loads.