Punching Shear Strength of Reinforced Concrete Flat Slabs with Macro Synthetic Fibers

Abstract

Discrete macro fibers such as steel and synthetic have been recognized as an attractive material to improve concrete properties such as flexural toughness, shear strength, impact characteristics, deflection capacity and concrete ductility. In this paper, the effect of macro synthetic fibers on punching shear resistance and cracking behaviour of reinforced concrete slabs was investigated. A total of six reinforced concrete slabs were designed, instrumented and tested in displacement control mode, under monotonic center-point load in simply supported configuration. Synthetic fibers were added to the concrete slabs at dosage rates of 0.5% and 1% by volume. The results have shown a significant increase of the punching shear strength, energy absorption capacity and ductility of the slabs. The addition of 0.5% and 1% of macro synthetic fiber to the slab increased punching shear strength by 30% and 70% and increased energy absorbance by 40% and 80%, respectively.