Punching Shear Resistance of Steel Fiber Reinforced Concrete Flat Slabs

This paper deals with behavior and capacity of steel fiber reinforced concrete (SFRC) flat slabs under punching shear force. A total of twelve small-scale flat slabs of different dimensions that consisted of nine SFRC and three control steel reinforced concrete (SRC) ones were tested. Effect of steel fibers amount on punching shear cracking behavior and resistance of the slabs was investigated. The results show a significant increase of the punching shear capacity and considerable improvement of cracking behavior as well as good integrity of column-slab connection of the slabs with fibers. The slabs without fibers failed suddenly in very brittle manner, while, the fiber reinforced ones collapsed in more ductile type. At serviceability limit state, a strong reduction of average crack width up to approximately 70.8% of the SFRC slabs in comparison with SRC ones was observed. In addition, based on experimental data obtained from the author's study and literature, the paper performed an evaluation of accuracy of existing models and formulas in previous studies that used to predict punching shear resistance of SFRC slabs. The results from the evaluation show that the existing formulas gave inaccurate results with a large scatter in comparison with the testing results, and thus, a new formula should be proposed for more accurate estimation of punching shear resistance of SFRC slabs