Punching Shear Resistance of SFRC Flat Slabs with and Without Punching Shear Reinforcement

The punching shear capacity of steel fibre reinforced concrete (SFRC) flat slabs without shear reinforcement has been the subject of extensive investigations over the past 40 years. Past investigations have shown an increase in the failure load of around 30 to 60 % and a change to a very ductile failure mode. However, most of these tests were carried out on slabs with a thickness of less than 150 mm, and are thus of only limited practical relevance. In addition, only twelve tests are available with a combination of SFRC and conventional shear reinforcement. To partly make up for this lack of experimental data, a total of ten punching tests were carried out at the Technical University of Munich over the last three years. The experimental program included three reference tests without steel fibres and seven SFRC tests. All specimens were manufactured with conventional flexural reinforcement, a slab thickness of 250 mm and four specimens had stirrups or shear studs as punching shear reinforcement. The parameters varied were the fibre type and content as well as the flexural reinforcement ratio. All of the SFRC specimens showed a significant increase in the bearing and deformation capacity compared to reference specimens.