Civil Engineering Reference
In-Depth Information
The testing method is based on the picture frame test (Fig.
3.3
) and prescribes that:
In a square frame, of which each corner can be freely rotated, a specimen with the pre-
scribed tension introduced in the directions of warp and
fill is mounted with the frame
aligned in the direction of the woven thread. Under this condition, the square frame is
deformed in the diagonal direction, and in-plane shear stiffness is determined from the
relationship between the load obtained and displacement (MSAJ/M-01:
1993
).
16 cm or bigger and should be designed in order to
allow the correct mounting and deformation of the prestressed sample. In addition,
the standard describes the correct sampling and preparation of the specimens (three
or more) which should be taken from an area of the fabric which is 1/10 of the
overall width from each selvage, avoiding the portion within 100 cm from the end.
The sample should be pre-tensioned, from 1.0 to 3.0 kN/m according to the
material, and aligned with the frame.
During the test the sample is repeatedly deformed with a constant rate extension
(10 mm/min) three times in the diagonal direction up to the predetermined dis-
placement (shear deformation angle of the testing plane equal to 1
The tester should be 16 cm
×
°
) in positive and
negative directions.
The calculation of the in-plane shear stiffness is by means of the following
equations on the basis of the load-displacement curves obtained by removing the
first cycle and averaging the second and the third.
N
XY1
þ
N
XY2
c
1
þ c
2
¼
F
2
p
L
c
1
þ c
2
F
1
þ
G
t
¼
ð
3
:
24
Þ
ð
Þ
q
L
2
8
<
9
=
L
2
p
2
d
1
þ
p
4
tan
1
c
1
¼
2
a
1
¼
2
d
1
þ
L
2
p
ð
3
:
25
Þ
:
;
q
L
2
8
<
9
=
L
2
p
2
d
2
þ
p
4
tan
1
L
2
p
c
2
¼
2
a
2
¼
2
ð
3
:
26
Þ
:
;
d
2
þ
where:
N
XY1
value of in-plane shear stress per unit width corresponding to F
1
N
XY2
value of in-plane shear stress per unit width corresponding to F
2
G
t
in-plane shear stiffness per unit width
L
length of one side of the plane of in-plane shear deformation tester
F
load applied in diagonal direction of in-plane shear deformation tester
ʳ
1
ʱ
1
(=2
ʱ
1
)
shear deformation angle (rad) corresponding to
ʳ
2
ʱ
2
(=2
ʱ
2
)
shear deformation angle (rad) corresponding to
ʴ
1
absolute value of displacement corresponding to
ʱ
1
in diagonal direction
of shear deformation tester
ʴ
2
absolute value of displacement corresponding to
ʱ
2
in diagonal direction
of shear deformation tester
N
XY1,
N
XY2,
ʳ
1
and
ʳ
2
are absolute values
