The Maximum Punching Capacity of Flat Slabs

Abstract:

Two ways how to determine maximum punching resistance of flat slabs with shear reinforcement are currently used. The first way is verification of the concrete strut capacity at the column periphery defined as V_Rd,max. The second limit is defined as k_max multiple of the punching shear resistance without shear reinforcement V_Rd,c. The values of k_max are proposed usually in between 1.4 and 2.0. Results of the experimental tests are presented in the paper that were focused on above mentioned limits, whether failure of the struts can precede any other form of punching failure that is limited by k_max*V_Rd,c. Two experimental slab samples reinforced with high amount of shear reinforcement that increased punching capacity above capacity of the concrete struts were tested together with two slab samples cast without shear reinforcement. Comparison has shown that punching resistance of flat slab with shear reinforcement has been 1.7 times higher than resistance without shear reinforcement. While some standards allow for use k_max value of 1.9 in this case. This indicates that limits based only on the k_max factors may overestimate actual maximum punching shear resistance.

• Periodical: Solid State Phenomena (Volume 259)
• Pages: 232-237
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.259.232
• Online since: May 2017
• Authors: Lucia Majtánová*, Jaroslav Halvonik, Ján Hanzel
• Keywords: Concrete Strut Capacity, Flat Slab, Punching, Resistance, Studs

References

[1] Zsutty, T. (1968) Beam shear strength prediction by analysis of existing data. ACI Journal V. 65(11): pp.943-951.

[2] Muttoni A., Schwartz, J. (1991) Behaviour of beams and punching in slabs without shear reinforcement, IABSE Colloquium, Vol. 62, Zurich, Switzerland, 1991, pp.703-708.

[3] Regan P.E. (2000): Shear Reinforcement of Flat Slabs, in Proceedings of International Workshop on Punching Shear Capacity of RC Slabs, TRITA/BKN, Bulletin 57, 2000, pp.97-107.

DOI: 10.14359/14937

[4] Muttoni A., Fernández Ruiz M. (2008) Shear strength of members without transverse reinforcement as function of critical shear crack width, ACI Structural Journal, V. 105, No 2, 2008, pp.163-172.

DOI: 10.14359/19731

[5] EN1992-1-1 Design of Concrete Structures, Part 1-1 General Rules and Rules for Buildings, May (2004).

[6] Fédération Internationale du Béton (fib), Model Code 2010 - Final draft, Vol. 1, Fédération internationale du béton, Bulletin 65, Lausanne, Switzerland, 2012, Vol. 2.

DOI: 10.35789/fib.bull.0104

[7] Muttoni, A., Fernández Ruiz, M., (2012) The levels-of-approximation approach in MC 2010: applications to punching shear provisions, Structural Concrete, Ernst & Sohn, Germany, Vol. 13, No. 1, 2012, pp.32-41.

DOI: 10.1002/suco.201100032

[8] Siburg C., Hausler F., Hegger,J. (2012) Flat slab punching design according to German annex of Eurocode 2, Bauinginieur, Volume 87, May 2012, pp.216-225.

[9] Hegger J., Häusler F., Ricker M. (2008) Critical review of the punching shear provisions according to Eurocode 2 (in German: Zur Durchstanzbemessung von Flachdecken nach Eurocode 2), Beton- und Stahlbetonbau, Vol. 103, No. 2, 2008, pp.93-102.

DOI: 10.1002/best.200700596

[10] Einpaul,J., Bujnak,J., Ruiz,M., and Muttoni,A. (2016) Study on influence of column size and slab slenderness on punching strength, ACI Structural Journal, V. 113, January-February 2016, pp.135-145.

DOI: 10.14359/51687945

[11] Hegger J., Siburg C., Kueres D. (2016) Proposal for punching shear design of flat slabs and column bases based on Eurocode 2, RWTH Aachen University, Germany, Presentation from CEN TC250/SC2/WG1/TG4 meeting in Copenhagen, 28. -29. January (2016).

DOI: 10.1016/j.engstruct.2016.12.064

[12] Ruiz M.F. - Muttoni,A. (2009) Application of Critical Shear Crack Theory to Punching of RC Slabs with Transverse Reinforcement, ACI Structural Journal V. 106 No. 4, July – August 2009, pp.485-494.

DOI: 10.14359/56614

[13] Feix,J. - Hausler,F. - Walkner,R. (2011): Necessary Amendments to the Rules for Punching Design According to EN 1992-1-1, in Proceedings of Workshop Design of Concrete Structures and Bridges using Eurocodes, Bratislava 2011, pp.21-27.

[14] Bujnak,J. - Gavura,S. (2012).

[15] Lips, S.; Fernández Ruiz, M.; and Muttoni, A. (2012) Experimental Investigation on Punching Strength and Deformation Capacity of Shear- Reinforced Slabs, ACI Structural Journal, V. 109, No. 6, Nov. -Dec. 2012, pp.889-900.

DOI: 10.14359/51684132

[16] Muttoni, A., Ruiz, F. (2015) Proposal for punching shear provisions based on CSCT, Presentation from CEN TC250/SC2/WG1/TG4 meeting in Florence, 12. -13. March (2015).