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Effect of Confinement on StrengthConcrete Columns
of Reinforced
Chai Jaturapitakkull Kraiwood Kiattikomo12
Somchai Chucheepsaku13 and Anek Siripanichgorn4
King Mongkut’s Institute of Technology Thonburi
Abstract
The objective of this study is to investigate the effect of confinement on the
strength of concrete columns subjected to eccentric load when using different spacing
of tied reinforcement. A total number of 48 reinforced concrete columns was tested.
Each column has a cross sectional area of 20x30 cm with a height of 120 cm and is
reinforced with 6 main bars with a diameter of 12 mm. The samples of columns were
divided into 4 groups and each group had 12 columns. The first group was the columns
without any confinement, the rests were the columns with confinement provided by
tied bars having a diameter of 6 mm. The second, third, and fourth groups were the
columns with a spacing of tied bars of 5 cm, 10 cm, and 20 cm, respectively. Each
group was tested in 4 cases, having load eccentricity of 0, 3, 6, and 9 cm, respectively,
from the centroid of the column. Three columns were tested for each case.
The results showed that the columns with tied bar resisted higher load than
the one without any tied bar. It was found that the columns with heavy confinement
gave higher compressive loads and larger lateral deflections as compared with the
columns of less confinement. For columns without any confinement, the failure
occurred suddenly when the columns reached their ultimate loads. In contrary to the
columns with confinement, cracks were observed at the covering of the columns,
then spalling occured, after that the columns failed slowly.
’ Assistant Professor, Department of Civil Engineering
’ Associafe Professor, Department of Civil Engineering
3 Associate Professor, Department of Civil Engineering
4 Assistant Professor, Department of Civil Engineering
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Column Size (cmxcm) Height (cm)
20x30 120
20x30 120
20x30 120
20x30 120
Tie Spacing No. of Columns- - 12
[email protected] m 12
[email protected] m 12
[email protected] m 12
6-012
d060 0.05
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a : 6cm
DIAL GAUGE c
DIAL GAUGE dLLchLv&m4L+iIi
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(au*) (au*) (@% (@% fh Puvmaa~(ch)
AQ - 0 64.78 70.60 -5.82 -8.24
A3 - 3 55.30 57.40 -2.10 -3.66
10 6 1 66.48 1 47.13 ) +19.35 +41.06
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140
130
120
110
100
90
80
7 0
60
50
40
30
20
10
00 4 8 12 16 20 2 4 28
Strain of Column (x0.0001)
140
130
120
110
100
90
60
70
60
50
40
3 0
20
10
O$ 1 I I I I I I I I I 1 I I I
0 4 8 ,12 16 20 2 4 26
Strain of Column (x0.0001)
1 4 0
130
120
110
1 0 0
9 0
8 0
7 0
6 0
5 0
4 0
3 0
2 0
10
0
A6 Column
D6 Column
I I 1 I I 1 I 1 1 I I I I I I0 4 a 12 16 2 0 2 4 2 8
Strain of Column (x0.0001)
110 _I100 -
9 0 -
8 0 -
7 0 -
60 -
5 0 -
4 0 -
3 0
2 0
10
q A9 Column
+ B9 Column
0 C9 C o l u m n
A D9 Column
Strain of Column (x0.0001)
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90
8 0
7 0
6 0
7.0 505
Bs
4 0
3 0
A DO Column
0 CO Column
+ BO Column
q A0 Column
I I I I
2 4 6
Lateral Deflection (mm)
90
8 0
7 0
6 0
5 0
4 0
3 0
2 0
10
0
A 03 Column
0 C3 Column
+ 83 Column
q A3 Column
0 2 4 6
Lateral Deflection (mm)
8 0
6 0
0 2 4 6
Lateral ,Deflection (mm)
3151151 885. an” 2 0 U?Jn” 1 i@llUU 2 5 4 0 _
7 0
6 0
5 0
4 0
3 0
2 0
10
0
A D9 Column
0 C9 Column
+ B9 Column
0 A9 Column
16
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1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
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of Concrete
Strength of
Standards,
18
