Study of Failure Mode of Reinforced Concrete Flat Slabs with Openings and Studs

This work presents an experimental investigation on the behavior of nine reinforced concrete flat slabs with dimensions of 1800 x 1800 x 130 mm. The slabs were divided according to the number of openings adjacent to the column (reference slab, slab with two or four openings), as well as the presence or absence of stud shear reinforcement. The parameters evaluated in the research refer to the failure modes observed, vertical deflections, and concrete strains and flexural and shear reinforcement strains. It studied the influence of the openings in the maximum displacements, and deformations of steel and concrete of the flat slab with and without shear reinforcement. The influence of the openings near the column was analyzed and the contribution of the use of shear reinforcement to overcome the loss of resistance was analyzed. The experimental results were compared with ACI 318 and NBR 6118. The test results showed that the equations' punching shear resistance prediction for ACI 318 overestimated up to 131% in slabs with openings.