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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
Automation of the evaluation of bonded and unbonded prestressed concrete beams, according to brazilian
and french code specifications
According to the criteria of the Brazilian norm, resistant mo-
ment was 829.2 kN.m and ultimate moment was 771.9 kN.m.
The comparison of these values shows that the member has
an additional safety factor equal to 1.07 relative to breaking.
When using the French norm, the resistant moment value (807
kN.m) was 1.06 times higher than the ultimate moment (764.2
kN.m), which is lower than that obtained with the Brazilian norm
due to different load increment coefficients. As in the previous
example, in both cases ultimate moment was lower than the
resistant moment, and therefore, element safety relative to rup-
ture is ensured.
5. Final considerations
The increasing use of prestressing in Brazil and around the world
justifies the automation of design procedures of bonded and un-
bonded prestressed concrete elements mainly due to its building
advantages, as well as allowing reducing crack incidence and ele-
ment dimensions by the use of more resistant materials. Based on
the implementation of evaluation subroutines in the software pro-
gram according the recommendations of the Brazilian and French
norms, it is possible to directly apply the finite element numerical
model in the design of prestressed concrete elements.
As expected, service limit state evaluations relative to cracking of
the studied bonded and unbonded prestressing beams performed
according to the Brazilian and French norms yielded very similar
results, despite using different approaches. However, the French
norm approached proved to be simpler and faster, demanding
much less computational efforts.
Relative to ultimate limit state, it was observed that the safety mar-
gin obtained using the procedures of both norms were very similar.
6. Acknowledgements
The authors express their gratitude to CAPES (Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior), CNPq (Conselho
Nacional de Desenvolvimento Científico e Tecnológico) and RS
Engenharia for their support.
7. References
[01] RUDLOFF. Technical catalog. 2006. Available:
< http://www.rudloff.com.br/>. Accessed on April 12, 2010.
[02] BARBIERI, R. A. Modelo Numérico para Análise à
Figure 39 – Tab Cracking table - French code specification (rare load combination)
Figure 40 – Transversal displacement