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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
P. V. P. SACRAMENTO | M. P. FERREIRA | D. R. C. OLIVEIRA | G. S. S. A. MELO
It is noteworthy that in this paper it was used CSCT in its most accu-
rate version and if it had been used the version adopted in the new fib
code, results would be practically as conservative as those from ACI
(see Ferreira [1]).
The Brazilian code presented average results near to the expe-
rimental ones (average 1.01). By not limiting parameters such
as flexural reinforcement ratio and size effect, how does Eu-
rocode, NBR 6118 presented a coefficient of variation of 0.11,
lower than other codes. However, for 47% of slabs the punching
strength estimated according to these equations were unsafe.
This indicates that it is extremely necessary to review its re-
commendations in order to avoid this inadequate trend. It was
showed also that a simple change in the equation of this code
could change this trend of unsafe results, raising the average
to 1.14, equal to of the CSCT, but reducing the percentage of
unsafe results to only 9.5%.
8. Acknowledgements
The authors would like to acknowledge CNPq and CAPES for fi-
nancial support in all steps of this research.
Figure 1� � Trend of results according to the different theoretical methods presented
ACI 318
NBR 6118
Eurocode 2
TFCC
A
C
B
D
9. References
[01] FERREIRA, M. P. (2010). Punção em Lajes Lisas de
Concreto Armado com Armaduras de Cisalhamento
e Momentos Desbalanceados. Tese de Doutorado
em Estruturas e Construção Civil, Publicação
E.TD – 007 A/10 Departamento de Engenharia Civil
e Ambiental, Universidade de Brasília, Brasília, DF,
275p.
[02] ELSTNER, R. C., e HOGNESTAD, E., Shearing
Strength of Reinforced Concrete Slabs. Journal of the
American Concrete Institute, Proceedings, V. 53,
No. 1, Jul. 1956, pp. 29-58.
[03] MUTTONI, A., Punching Shear Strength of
Reinforced Concrete Slabs without Transverse
Reinforcement, ACI Structural Journal, V. 105, No. 4,
July-Aug. 2008, pp. 440-450.
[04] fib Bulletin 55, Model Code 2010 – First complete
draft, Volume 1,318p., 2010.
[05] fib Bulletin 56, Model Code 2010 – First complete
draft, Volume 2, 312p., 2010.