Punching shear behavior of steel fiber reinforced flat slabs in combination with punching shear reinforcement

The guideline “Steel Fibre Reinforced Concrete” published by the German Committee for Reinforced Concrete (DAfStb) in 2012 regulates the punching shear design of steel fiber reinforced flat slabs with and without punching shear reinforcement in Germany. The punching shear design of flat slabs without shear reinforcement is herein comprised as an additive design approach, consisting of the concrete contribution of a flat slab without shear reinforcement and the steel fiber contribution dependent on the post-cracking tensile strength of the steel fiber reinforced concrete. Regarding the punching shear design of flat slabs with shear reinforcement, the combination of the two contributions, steel fibers and punching shear reinforcement, is explicitly excluded due to a lack of experience and investigations. The national and international literature shows only eight steel fiber reinforced tests with punching shear reinforcement. These were either carried out with for Germany untypical punching shear reinforcement or failed due to bending in the test. Based on these experiments, no conclusions regarding the effectiveness and load-bearing behavior of steel fiber reinforced flat slabs in combination with punching shear reinforcement can be drawn.

For the systematic investigation of the punching shear capacity of steel fiber reinforced flat slabs with closed stirrups and shear studs as punching shear reinforcement, two series with three tests each were carried out. The results obtained show the potential for improving the punching shear capacity and permit the description
of the load-bearing behavior. Simplified, a theoretical load is calculated as the sum of the concrete and steel fibre contribution according to the DAfStb guideline “Steel fibre reinforced concrete” and the steel contribution according to DIN EN 1992-1-1+NA(D). Comparing this theoretical load with the experimental load allows to evaluate the validity of this simplified approach.

x

Related articles:

Issue 02/2017 Flat slabs and foundations

New punching shear reinforcement systems

The structural design of flat slab systems is usually governed by the punching shear resistance of the slab. To achieve a sufficient punching shear resistance at reasonable slab thickness, shear...

more
Issue 06/2022

Experimental investigations on punching shear of flat slabs made of carbon-reinforced concrete

So far, European standards do not stipulate generally applicable verification rules for the punching shear of slabs made of carbon-reinforced concrete. In addition, regulations on the structural...

more
Issue 02/2019 New experimental results on punching shear behavior of flat slabs with varying amount of punching shear reinforcement

Reduction of punching shear reinforcement

With introduction of Eurocode 2 in Germany, the punching shear design provisions for flat slabs were revised. In consequence of limited anchorage conditions of punching shear reinforcement elements in...

more
Issue 10/2018 FILIGRAN TRÄGERSYSTEME

Filigran punching shear reinforcement newly assessed

The FDB Filigran punching shear reinforcement consists of spatial welded reinforcement elements with optimized geometry. The punching shear resistance of flat slabs is more than doubled by using FDB,...

more
Issue 11/2021 Monday, 15th November → Innovation workshop (6)

New European Assesment for punching shear reinforcement

Flat slabs made of reinforced concrete are supported directly on columns. The total height of the slab construction is reduced and the formwork effort is simplified because beams are done away with....

more