Shear design for carbon concrete in accordance with the new Eurocode 2

© RWTH Aachen Univeristy

The aim of the research project C³-V-I.14 was the development and validation of a consistent shear design model for carbon concrete components with shear reinforcement for the new edition of Eurocode 2.
In contrast to member design for bending, no validated models are yet available for shear design of carbon concrete. In order to close this research gap, new component tests were carried out in project V-I.14 by IMB of RWTH Aachen University on slab segments for a member depth relevant for textile reinforced concrete and carbon concrete with and without shear reinforcement. 60 single-span beams and 23 single-span beams with cantilever to reproduce a continuous slab effect were investigated. Both planar and C-shaped shear reinforcement was able to increase shear resistance of slab segments compared to reference tests. For thicker slabs (h = 14.5 cm) the shear reinforcement is more effective than for thinner slabs (h = 10 cm). These new experiments complement two databases that were built within the project. An evaluation of the databases with the model approaches discussed for new Eurocode 2 showed that the shear capacity of carbon concrete slabs without shear reinforcement with shear slenderness of 2.5 to 5.5 can expected to be determined with the same approach as for steel reinforced concrete. However, further investigations are necessary for a reliable prediction of the load-bearing capacity with shear reinforcement.

The approach planned in EC2 Draft 3 for components with shear reinforcement is not suitable for thin or thicker plates with non-metallic shear reinforcement without further adaptation. The high ultimate strength of the reinforcement cannot be fully activated due to the incomplete anchorage of the shear force reinforcement in bending compression and bending tension zone and the model discussed in draft 3 of the new Eurocode 2 systematically overestimates the ultimate limit state. A model with an additive reinforcement bearing capacity with a upper strain limit for the vertical shear force reinforcement seems more promising.

In particular, the effect of insufficient anchorage of shear force reinforcement and the strain limitation of the vertical reinforcement in thin slabs cannot be determined reliably based on the currently available data. The databases and the results of the new experimental investigations will be used in the successor project L9 to lay the foundation for a guideline for design of carbon concrete.

 

The results of the project are freely accessible in the final report (DOI: XXX)

Bielak, J.; Hegger, J.; Will, N.: Zwanzig20 ‒ Carbon Concrete Composite C³ ‒ C3-V-I.14 Querkraftbemessung für Carbonbeton nach dem neuen Eurocode 2 ‒ Schlussbericht 427/2020, Lehrstuhl und Institut für Massivbau. RWTH Aachen University, Aachen, (2020) ‒ DOI XXX.

 

Publications

  1. Bielak, Jan; Hegger, Josef; Schmidt, Maximilian: Shear Capacity of Carbon Fibre Textile Reinforced Concrete Slabs with Planar and C-Shaped Shear Reinforcement. In: Proceedings of Fiber Reinforced Polymer Reinforced Concrete Structures FRPRCS 14, 04.-07.06.2019, Belfast, United Kingdom.
  2. Bielak, Jan; Bergmann, Sarah; Hegger, Josef: Querkrafttragfähigkeit von Carbonbeton-Plattenbrücken mit C-förmiger Querkraftbewehrung. In: Beton- und Stahlbetonbau (2019), Iss. 7, pp. 465-475, DOI: 10.1002/best.201900001
  3. Bielak, Jan; Adam, Viviane; Hegger, Josef; Classen, Martin: Shear Capacity of Textile-Reinforced Concrete Slabs without Shear Reinforcement. In: Applied Sciences 9 (2019), 1382, DOI:10.3390/app9071382
  4. Bielak, Jan: Tragfähigkeit von Carbonbeton-Bauteilen mit Querkraftbewehrung. In: Tudalit e.V. und C³ – Carbon Concrete Composite e.V. (eds.): Tagungsband der 10. Carbon- und Textilbetontage, pp. 134-135.
  5. Bielak, J.: Praxisbeispiele zum Thema Querkrafttragfähigkeit. In: Tudalit e.V. und C³ – Carbon Concrete Composite e.V. (eds.): Tagungsband der 11. Carbon- und Textilbetontage, pp. 16-17.
  6. Bielak, J.; Will, N.; Hegger, J.: Zwei Praxisbeispiele zur Querkrafttragfähigkeit von Brückenplatten aus Textilbeton. Bautechnik 97 (2020), Iss. 7. (submitted)

RWTH Aachen University, Institut für Massivbau

Vorhabenleiter
Univ.-Prof. Dr.-Ing. Josef Hegger

Ansprechpartner
Jan Bielak, M. Sc.
+49 241 80-26830
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Laufzeit: 01.01.2018 bis 30.09.2019