One-way shear strength of circular voided reinforced concrete floor slabs

Generally, voided reinforced concrete floor slabs in building structures have a lower shear strength compared with solid slabs owing to the reduction in their cross-sectional area. This study shows that the void shape and material of the void-shaper also influence the shear strength of voided slabs. To verify these assumptions, one-way shear tests were conducted for four test specimens. The first was a conventional solid slab and the others were voided slabs. The voids had toroidal or ‘doughnut' shapes as well as non-doughnut shapes. The void-shaper was made of polypropylene plastic and glass-fibre-reinforced plastic. The test results showed that the shear strength of doughnut-type voided slabs was 73–78% of a solid slab and was superior to that of existing voided slabs. The shear crack angle changed with the void shape. A finite-element analysis was conducted to evaluate the influence of these parameters on the shear behaviour of the doughnut-type voided slab.