Experimental Study on Punching Shear Strength of Fiber Reinforced Concrete Slabs

This paper is part of an ongoing research project on punching shear strength of reinforced concrete flat slabs incorporating macro synthetic fibers. Results obtained from testing six slabs (1500 x 1500 x 150 mm) are reported and discussed in this paper. The slabs were reinforced with flexural reinforcement ratio of 0.9% and macro synthetic fibers were added at two volume fractions of 0.5% and 1.0%. Slabs were tested in simply-supported configuration system with center point load increasing monotonically in displacement control mode. Loads, slab deflection, strain in the concrete and steel were measured in the experiment and crack patterns and failure mode were observed. The results revealed noticeable enhancement in the punching shear capacity, cracking behavior, energy absorption and ductility of the reinforced concrete slab. The addition of macro synthetic fibers increased the punching shear strength by up to 17% and the energy absorption by up to 73% for the tested FRC slabs relative to the control slab. Furthermore, the slab deflection profile showed that the addition of fibers modify the shape of slab deflection which indicates that fibers help engaging the whole slab in carrying the applied load.