An investigation of punching shear in flat slabs with spherical voids using the finite element method

Flat slabs with voids allow for the reduction of the structure's self-weight by removing concrete from regions of the cross-section subjected to low stresses. However, the presence of voids impacts the behavior of these structures, especially under punching loads, and few studies have assessed the impact of different parameters on voided slabs. Thus, this study validated numerical modeling developed in the ANSYS software, using the finite element method, based on 17 experimental slabs from the literature. The numerical simulation indicated a good approximation of the deformation behavior of the structure, as well as a similar mode of failure. Once validated, the model evaluated different parameters in spherical voided slabs. The results showed significant impacts on the rupture load, ductility, or stiffness when varying the void's presence, position, diameter, concrete properties, slab thickness, flexural reinforcement ratio, and shear reinforcement. In voided slabs, the critical situation occurred when inserting the spheres in a region very close to the column, which reduced the rupture load by about half, when compared to a solid slab.