Punching shear behaviour of steel fibre reinforced flat slabs with punching shear reinforcement

The guideline "Steel Fibre Reinforced Concrete" published by the German Committee for Reinforced Concrete (DAfStb) contains the current normative regulations for the punching shear design of steel fibre reinforced flat slabs. Due to a lack of sufficient experience and knowledge, a consideration of the combined action of steel fibres and shear reinforcement was explicitly excluded. While numerous punching shear tests on steel fibre reinforced flat slabs without shear reinforcement are available in literature, only eight tests in combination with shear reinforcement are known to the authors. These few tests used types of shear reinforcement which are not common for engineering practice in Germany, or showed bending failure, which limits the reliability of statements about the behaviour of such a combination. In this context and the expected favourable behaviour, seven tests were carried out to systematically investigate the punching shear behaviour of steel fibre reinforced flat slabs with stirrups and shear studs as shear reinforcement. The test program included one fibre reinforced test without punching shear reinforcement, two fibre-free and four fibre reinforced tests with punching shear reinforcement. This paper describes the experimental investigations carried out and discusses the results obtained.