Experimental Study on Punching Shear Performance of Two-Layer Normal and Steel Fiber Reinforced Concrete Slabs

Hawkar Azeez Ahmed; Esra Mete Guneyisi

doi:10.55524/ijirem.2026.13.3.18

Abstract

This study experimentally investigates the punching shear response of two-layer slabs having normal concrete (NC) with steel fiber reinforced concrete (SFRC). The concept of the two-layer system is simple: fibers are only cast in the areas where the critical cracks are likely to occur, thus minimizing the amount of the more costly fibered concrete. A total of 15 flat-slab specimens were cast and divided into five parametric groups, with a normal concrete slab as the reference slab, and the other slabs having different variables such as the fiber height ratio through the slab depth, the flexural reinforcement ratio, the lateral size of the SFRC zone around the column, the load eccentricity, and the fiber volume fraction. Each specimen was loaded to failure and the response was monitored using load-deflection curves, cracking and ultimate loads, steel and concrete strains, punching cone geometry, ductility, and secant stiffness. The measured capacities were then compared with the ACI 318 punching provisions. The results indicated that the through-depth location of the fibers is an independent design variable, that the fibered zone is effective only if it is sufficiently thick to intersect the incipient failure surface, and that the dosage of fibers increases both the cracking load and the ultimate load. However, most of the fibre benefit was negated by load eccentricity which also altered the mode of failure. However, ACI predictions were conservative for each concentric specimen, and did not consider the contribution of the fibers, the zone-size effect, or the eccentric failure mode.

Keywords

Flat Slab; Punching Shear; Slab-column Connection; Steel Fiber Reinforced Concrete; Two-layer Slab.

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Cites this article as

H. A. Ahmed, E. M. Guneyisi, "Experimental Study on Punching Shear Performance of Two-Layer Normal and Steel Fiber Reinforced Concrete Slabs", International Journal of Innovative Research in Engineering and Management (IJIREM), Vol-13, Issue-3, Page No-153-163, 2026. Available from: https://doi.org/10.55524/ijirem.2026.13.3.18