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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 3
P. P. NASCIMENTO | R. B. GOMES
|
L. L. J. BORGES
|
D. L. DAVID
to concrete crushing. Of all strengthened columns, only P8, with
three pairs of connectors, showed crushing strain.
All strengthened columns had their failure loads increased when
compared to original reference column P1. The number and posi-
tion of connectors influenced loads and the failure mode of the
models assayed. Columns with a single pair of connectors pre-
sented higher failure loads than those columns whose pair of con-
nectors was placed further from the centre. Column P3, whose
connectors were closer to the centre (105 mm), failed at 390 kN,
whereas P4, whose connectors were placed 300 mm from the cen-
tre, failed at 470 kN. Column P5 had its pair of connectors placed
550 mm from the centre, and its failure load occurred at 500 kN.
Columns P6A (P
u
= 430 kN) and P7 (P
u
= 480 kN), strengthened with
two pairs of connectors, had their outer pair of connectors placed 550
mm from the centre. The inner pair was located 300 mm from the
centre in column P6A and 205 mm in column P7. These columns
showed that, unlike columns strengthened with only one pair, there is
an increase in failure load as the inner pair of connectors approaches
the centre of the column (P7). The failure mode of these models also
occurred abruptly due to uncoating of the strengthening concrete.
Column P8, whose three pairs of connectors were placed 105 mm,
300 mm and 550 mm away from the centre, revealed the greatest
failure load of all the columns tested. The failure load of column P8
was 1.15 times higher than that of column P2.
The results showed that the use of this type of connectors can
be a viable option, providing a significant increase in failure load,
in strains and in horizontal displacements. Spacing between con-
nectors, positions and numbers of inappropriate connectors may,
despite the possibility of increase in failure load, lead to sudden
failures with displacement of the compressed section.
5. Acknowledgements
The authors gratefully acknowledge to CNPq and Procad/Capes
for their financial support. They also thanks to Carlos Campos
Consultoria Limitada, Impercia and Realmix for providing materi-
als and for performing material characterization tests.
6. References
[01] MELLO, E. L. Reinforced concrete: Limited resistance
to flexure under combined bending and axial
compression loads. University of Brasilia Ed.,
FINATEC, Brasília, 2003. 224 p.
[02] ADORNO, A. L. C. Theoretical and experimental
analysis of concrete columns and reinforced concrete
columns under eccentric load. D.Sc. thesis,
Department of Civil and Environmental Engineering,
University of Brasilia, Brasilia, DF, Brazil, 399p, 2004.
(In Portuguese).
[03] ARAÚJO, L. M. B. Theoretical and experimental
analysis of reinforced concrete columns subjected
to axial load and flexure. M.Sc. thesis, Federal
University of Goias, Goiânia, Brazil. 196p, 2004.
(In Portuguese).
[04] NASCIMENTO, P. P. Reinforced concrete columns
strengthened with carbon fibers and self-compacting
concrete (CAA). 2006. 97f. UEG, Anápolis,
Goiás, 2006.
[05] OMAR, M. Y. M. Experimental analysis of reinforced
concrete columns strengthened with self-compacting
concrete (CAA). M.Sc. thesis, Federal University
of Goias, Goiânia, Brazil. 266p, 2006. (In Portuguese).
[06] SAHB, K. F. P. Experimental analysis of reinforced
concrete columns under eccentric load strengthened
with self-compacting concrete (CAA) and anchor bolts.
M.Sc. thesis, Federal University of Goias, Goiânia,
Brazil. 224p, 2008. (In Portuguese).
[07] EUROPEAN FEDERATION FOR SPECIALIST
CONSTRUCTION CHEMICALS AND CONCRETE
SYSTEMS (EFNARC). Specification and guidelines
for self-compacting concrete. In: EFNARC.
February, 2002.
[08] GOMES, P. C. C. Optimization and Characterization
of High-Strength Self-Compacting Concrete. 2002.
139f. D.Sc. Thesis, Universitat Politècnica de
Catalunya, Barcelona, 2002.
[09] BRAZILIAN ASSOCIATION STANDARDS.
NBR 6118:2003 – “Design of concrete structures”.
Rio de Janeiro, 2004, (in Portuguese).
[10] ACI COMMITTEE 318. Buiding Code Requirements
for Reinforced Concrete and Commentary – ACI
318/02. Detroit, American Concrete Institute, 2001.