Effect of Shape, Number, and Location of Openings on Punching Shear Capacity of Flat Slabs

Abstract

Experimental evidence have proved that punching shear capacity of flat slabs deteriorate with the presence of openings located within the critical perimeter around columns. It is understood that this deterioration varies inversely with the distance of openings from column’s face. However, effect of the shape of openings on punching shear capacity is not well known. This study presents experimental results of 14 flat specimens to investigate the effects of the number (2 and 4), shape (circular, square, and rectangular), and location (1 and 4 times of slab’s thickness from column’s face) of openings on punching shear strength. It was found that circular openings had least influence on punching capacity followed by square and rectangular openings, respectively. Further, placing openings at a distance of four times the slab’s thickness from column’s face had minimal impact on punching capacity. Further, increasing the number of openings from 2 to 4 substantially reduced the punching capacity. An effort was made to predict the punching capacities of all specimens using the descriptive equations of ACI 318-19 and Eurocode 2. Mean of the ratio of experimental to analytical results and standard deviation of ACI equations were found to be more accurate than those of Eurocode 2 predictions.

Studying the Effects of Opening Size and Location on Punching Shear Resistance of Flat Slabs Using ANSYS V.19

“…Varying sizes and locations lowered shear capacity (11.43%-29.25%) and stiffness (0.31%-83.00%) compared to solid slabs. Yooprasertchai et al [5] studied the effects of numbers, shapes (circle, square, rectangular), and locations of openings on the punching shear capacity of flat slabs. The findings showed that square and rectangular openings had the least impact on capacity reduction compared to circle openings.…”

Punching Shear Strength Prediction for Reinforced Concrete Flat Slabs without Shear Reinforcement

“…Similarly, the flexural reinforcement can also increase the punching shear capacity of the slab-column connection for flat slabs with or without shear reinforcement [19]. Other factors that may affect the punching shear strength may include the presence of openings and their shape, size, and location [20]. The punching shear capacity deteriorates if the opening is located within the critical perimeter around the column.…”

Two-Way Shear Resistance of FRP Reinforced-Concrete Slabs: Data and a Comparative Study

“…However, the mechanism of the two-way shear of the slabs is complicated; thus, it is still open for investigation [3][4][5][6]. The two-way shear resistance of concrete slabs that are without shear reinforcements is composed of several resistance mechanisms, as follows: (1) flexure reinforcements resist shear through using dowel shear; (2) aggregates resist shear across the sides of the diagonal concrete crack through using aggregate interlock and friction; (3) uncracked concrete resists shear through using direct shear [7][8][9].…”