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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 3
Experimental analysis of reinforced concrete columns strengthened with self-compacting concrete
and connectors
1. Introduction
This study consists of an experimental program included in a re-
search area developed at the School of Civil Engineering of Uni-
versidade Federal de Goiás (Federal University of Goiás). Aiming
at experimentally comparing the formulation suggested by Mello
(2003), Adorno (2004) assayed 12 columns of simple concrete and
reinforced concrete subjected to combined bending and axial com-
pression under an initial eccentricity of up to 30 mm. Araújo (2004)
complemented this work assaying nine columns with different
rates of reinforcement and initial eccentricities of 30 mm to 60 mm.
The experimental and theoretical results with greater concordance
occurred in the cases of smaller eccentricities. Omar (2006) stud-
ied the behavior of columns strengthened by self-compacting con-
crete (SCC) on the compressed face and by tension reinforcement
on the tensioned face. Nascimento (2006) investigated columns
strengthened with SCC on the compressed face and with carbon
fiber on the tensioned face. In their works, Omar (2006) and Nasci-
mento (2006) observed load capacity increase on columns under
combined bending and axial compression and strengthened with
SCC on the compressed face, however, uncoating of the strength-
ening concrete was also confirmed.
To reduce the effects of premature uncoating of the strengthening
concrete and consequently of abrupt column strain, Sahb (2008)
suggested improving the link between substrate and strengthen-
ing concrete by adding anchor bolts in various amounts and posi-
tions. Sahb obtained considerable increase mainly in failure load.
Choosing to use anchor bolts and SCC can be considerably posi-
tive, nevertheless a greater number of connectors has been shown
necessary to obtain a more ductile failure mode.
Based on the findings of previous studies, this work investigates
columns submitted to combined bending and axial compression
and strengthened with SCC on the compressed face. In addition,
the interfacial zone between differently aged concrete is strength-
ened with open stirrups acting as connectors.
This study’s main goal is to check the possibility of strengthening
reinforced concrete columns aiming at an increase of ductile failure
load to avoid uncoating and enabling a failure by concrete crushing
and steel yield. The use of connectors produced with steel bars fixed
on the columns’ stirrups is a substitute to anchor bolts used by Sahb
(2008) and is, to some extent, often used in civil construction.
All strengthened columns had their loads increased when com-
pared to the original reference column P1. The number and posi-
tion of connectors influenced loads and failure modes of the mod-
els assayed. Both the distance from the center and the spacing
Figure 1 – Dimensions of original columns (mm)
Figure 2 – Cross-section of tested specimens (e = Initial eccentricity; P= Load; mm)
initial