Evaluation of punching shear strength of voided transfer slabs

Abstract

To satisfy the various space demands of occupants in high-rise buildings, such buildings are often constructed with different structural systems along the height of the building, which causes vertical irregularity in the structural system. In buildings with a vertically irregular structural system, transfer slabs are often used to transfer loads from the upper part to the lower part of the building. The transfer slab can perform more efficiently by placing voids in slab regions that do not resist a high level of slab loads. This study evaluated the punching shear strength of voided transfer slabs by conducting experimental tests on five transfer slab specimens. Based on the test results, methods were developed for accurately calculating the punching shear strength of voided transfer slabs.

Reduced Volume Approach to Evaluate Biaxial Bubbled Slabs’ Resistance to Punching Shear

“…Zones subjected to concentrated loads, particularly the slabcolumn connection area, are the most vulnerable and crucial areas of the biaxial hollow slab. In comparison to solid slabs, experimental research on biaxial hollow slabs has shown that the punching shear region's perimeter drastically decreased during failure [15,21,[24][25][26][27].…”

“…Numerous factors can impact a biaxial voided slab's punching shear capacity, including the void's size, pattern, shape, and distance from the column face [1][2][3]5,6,[9][10][11]15,21,[23][24][25][26][27][31][32][33][34]. Calculations for the critical shear perimeter and, in turn, the punching shear resistance of a solid cross-sectional slab cannot be used directly for voided reinforced concrete slabs.…”

“…Numerous factors can impact a biaxial voided slab's punching shear capacity, including the void's size, pattern, shape, and distance from the column face [1][2][3]5,6,[9][10][11]15,21,[23][24][25][26][27][31][32][33][34].…”

“…It has been shown that approaches that just take into account the voiding formers crossing the control shear perimeter might not provide reliable estimations. Such approaches were shown to be particularly erroneous, especially for the punching strength of biaxial voided slabs, as the voiding formers were positioned beyond the control shear perimeter [25]. Based on the arguments mentioned above, it is advised to include a section situated at a distance of (4𝑑) from the column's perimeter in the zone of impact that voiding formers are thought to have on the shear resistance of biaxial voided slabs.…”

Punching Shear Strength of Voided Slab: Literature Review and Evaluation of Design Codes

“…Voided slabs are considered an attractive solution for long-span floors. They overpass solid flat slabs due to their economic advantages and the associated reduction in materials [1][2][3][4][5][6][7]. A voided slab consists of hollow plastic voids placed within the slab soffit between the tension and compression steel reinforcements, as shown in Figure1.…”