2777
Technical Committee 212 /
Comité technique 212
respectively. One of the failure modes of a tested specimen is
also shown in Figure 4.
Table 1. Dimension of the FRP tube specimen
Classification
Number of
specimen
Thickness
(mm)
Width
(mm)
3
2.8
3
4.2
Split disk
test
3
5.6
30
3
2.8
3
4.2
Filament
winding
FRP Compressive
test
3
5.6
L= 600
D
=
300
Tensile test
of inner arc
3
3.9
25.3
Tensile test
of outer arc
3
3.7
28.5
Pultruded
FRP
Tensile test
of rib
3
3.1
24.7
Table 2. Test results
Classification
Thick
ness
(mm)
Failure
load
(kN)
Ultimate
Strength
(MPa)
Modulus of
elasticity
(MPa)
2.8
62.3
294.6
22.2
4.2
112.7
326.9
23.3
Split disk
test
5.6
157.7
318.8
22.6
2.8
254.9
194.1
N/A
4.2
507.4
258.2
N/A
Filament
winding
FRP Compressive
test
5.6
647.1
247.5
N/A
Tensile test
of inner arc
3.9
25.6
260.1
22.4
Tensile test
of outer arc
3.7
22.8
214.2
27.9
Pultruded
FRP
Tensile test
of rib
3.1
29.8
387.4
31.4
Figure 4 Failure mode.
The mechanical properties were determined from the
experiments conducted by changing the thickness. In the test,
three sets of tests with different thickness and each set consists
of three specimens are prepared. Specimens were taken from the
FRP tube and the properties were, then, calculated by averaging
the results obtained from the split-disk test, compression test,
and tensile test. From the tests result, it can be observed that the
mechanical properties for the FRP tube specimens were almost
similar. In the specimen preparation three different compressive
strengths of concrete, i. e., 19.2MPa, 34.5MPa, and 44.0MPa,
are used and the strength of concrete at the age of 28 days was
measured by tests.
2.2
Uniaxial Compression Tests of HCFFP
For estimating the compressive strength of HCFFP, uniaxial
compression tests on HCFFP members are conducted. It was
observed that the HCFFP specimens are finally failed after the
rupture of filament winding FRP. From the experiment, load
versus displacement at the upper part of a loading plate and the
load versus strain measured at the middle of the specimen are
obtained. The axial stress versus axial strain of confined
concrete specimen is shown in Figure 5.
It can be observed that the uniaxial compressive strength of
HCFFP is increased if the concrete strength and the thickness of
exterior filament winding FRP tube is increased. This tendency
is also similar to that of existing CFFP member used currently
in practice.
(a) 2.8mm FFRP
(b) 4.2mm FFRP
(c) 5.6mm FFRP
Figure 5 Axial stress-strain relationship of HCFFP specimen.
2.3
Flexural Test of HCFFP
For estimating the flexural strength of HCFFP, flexural tests on
HCFFP members are conducted. A total of 9 specimens, 3 sets
of test with 3 specimens for each set, were tested under four-
point bending loads as shown in Figure 6. In the test, specimens
with 3 different filament winding thicknesses, i.e., 2.8mm,
4.2mm, and 5.6mm, are used. It was observed that the HCFFP
specimens are finally failed after the rupture of filament
winding FRP. From the experiment, load versus displacement
measured at the middle and quarter points of span length of the
specimen is obtained.
It was observed that the moment estimated at failure of the
HCFFP specimens is almost similar regardless of the
