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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
L. A. SPAGNOLO JR | E. S. SÁNCHEZ FILHO |
M. S. L. VELASCO
The angles
q
CR
,
e
q
,
CIN
q
are very similar, and the low coefficient
of variation of the ratio
.
theor
u
exp u,
V V
,
shows that the CSM and the
bond model presented form a consistent approach to study the shear
strengthening of reinforced concrete beams with CFC
U
stirrups.
Due to a limited number of available experimental results, the au-
thors’ opinion is that it is premature to corroborate the CSM as a
consistent and valid approach to the design of CFC stirrups for
reinforced concrete beams. The research methodology presented
only indicates that new theoretical approaches to this field should
be taken into account. Research in this area must continue with
more tests to obtain the accurate theoretical model and provisions
for the design of shear strengthening.
Table 3 – Test results
Beam
f
c
(kN)
CFC
layer
P
CR
(kN)
Ultimate strain (%)
Maximum
deflection
(mm)
LVDT 2
P
u,exp
(kN)
V
u,exp
(kN)
V
u,ref
V
u,exp
Failure
type
Steel
CFC
stirrup
Long.
Transv.
VR1
48.44
–
70.00
2.87
5.51
–
13.05
407.22
203.61
–
DT
VI-1
51.73
1
165.41
4.21
4.25
7.40
19.19
552.79
276.40
1.36
DTD
VI-2
51.73
2
166.97
4.58
6.71
4.75
17.91
586.65
293.33
1.44
DTD
VI-3
52.30
3
168.55
3.71
7.46
4.53
17.28
590.13
295.07
1.45
DTD
VR2
49.92
–
65.00
2.24
0.86
–
12.89
302.50
151.25
–
DT
VII-1
50.94
1
111.68
2.06
1.55
2.08
12.52
433.34
216.67
1.43
DTD
VII-2
51.73
2
135.37
2.72
1.63
5.46
12.60
466.57
233.29
1.54
DTD
VII-3
52.30
3
140.34
2.60
0.75
4.43
13.31
416.30
208.15
1.38
DTD
Average
1.43
Standard deviation
0.06
Coefficient of variation (%)
4.41
DT= diagonal tension; DTD= diagonal tension with CFC debonding
(in this order).
Table 4 – Test beams data
Beam
(°)
CR
(°)
e
(°)
CIN
V
u,exp
(kN)
V
u,theor
(kN)
CIN
CR
CIN
e
V
u,theor
V
u,exp
VI-1
39
33.63
43.06
276.40
250.07
0.91
0.78
1.11
VI-2
41
40.04
45.00
293.33
259.83
0.91
0.89
1.13
VI-3
42
41.38
46.16
295.07
266.85
0.91
0.90
1.11
VII-1
38
44.97
38.30
216.67
201.00
0.99
1.17
1.08
VII-2
40
41.93
40.82
233.29
215.43
0.98
1.11
1.08
VII-3
39
43.75
42.36
208.15
224.49
0.92
1.03
0.93
Average
0.94
0.98
1.07
Standard deviation
0.04
0.15
0.07
Coefficient of variation (%)
4.21
15.14
6.79
VR1*
40
30.37
35.94
203.61
207.64
1.11
0.85
0.98
VR2*
34
**
26.96
151.25
141.98
1.26
–
1.07
(*) Not considered in statistical analysis. (**) This value failed to be recorded.