State of research and prospects

Optimizing the shear design of slabs

A significant amount of the used concrete volume is applied to slab structures where shear design is often determinative of the dimensioning. Since applying shear reinforcement to slabs is elaborate, structural engineers intend to omit shear reinforcement in in-situ concrete slabs in construction practice. The current shear design approach for components without shear reinforcement according to EC2 is semi-empirical and was calibrated using a database of shear tests on simply supported single-span beams under concentrated loads. Therefore, capacity increasing influences due to more realistic

multi-span structural systems with distributed instead of concentrated loads are currently not considered in shear design. Tests with different loading show considerable potential for increases in shear capacity in the area of internal supports of continuous slab systems (Fig., [1, 2]) which could be taken into account in future generations of standards.

Additional tests will be carried out to check whether an arching effect occurring in continuous RC slab systems can be captured for structural analysis. This effect results from load-dependent Compressive Membrane Action and was already investigated in the past with regard to flexural and punching behavior of reinforced-concrete slabs, see e.g. [3, 4]. Considering this additional capacity-increasing influence in shear design of slabs could have a favorable effect due to a more accurate reflection of the slab’s load-bearing behavior, particularly when assessing existing structures.

Related articles:

Issue 2017-02 Effective width for shear

Shear capacity of RC slabs under concentrated loads

The present design rules for the shear capacity of reinforced concrete (RC) members without shear reinforcement in Eurocode 2 were calibrated based on a database containing the experimental results of...

more
Issue 2014-02 Punching shear tests on precast concrete slabs lead to European Technical Approval (ETA)

With projecting loops to peak load –

Flat slabs made as precast reinforced-concrete slabs with lattice girders and an effective in-situ concrete topping prove to be cost-efficient. Nevertheless, such flat slabs – in contrast to line...

more
Issue 2017-02 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 2021-02

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...

more
Issue 2019-02 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