Civil Engineering Reference
In-Depth Information
the design stresses predicted by analysis. In addition, the standard includes an
appendix including the procedure for determining the modulus of elasticity.
The method is based on the theory of elasticity applied to fabrics. Due to the
assumed orthotropic plane stress properties of architectural fabrics and the assumed
negligible effect of shear stress in a fabric, the general relationship between stress
and strain is
r
i
¼
C
ij
e
j
ð
:
Þ
3
9
where:
σ
stress
Ɛ
strain
C stiffness matrix
here simplified as:
¼
r
w
r
f
e
w
e
f
C
11
C
12
C
12
C
22
ð
3
:
10
Þ
where:
E
w
C
11
¼
ð
:
Þ
3
11
1
m
wf
m
fw
E
f
C
22
¼
ð
3
:
12
Þ
1
m
wf
m
fw
m
fw
E
w
C
22
¼
ð
3
:
13
Þ
1
m
wf
m
fw
C
12
¼
C
21
ð
3
:
14
Þ
E
w
m
wf
¼
E
f
m
fw
ð
3
:
15
Þ
σ
w
stress in warp direction
σ
f
stress in
fill direction
strain in warp direction
Ɛ
w
strain in
fill direction
Ɛ
f
E
w
modulus of elasticity in warp direction
E
f
modulus of elasticity in
fill direction
ʽ
wf
is the
fill direction strain caused by unit strain in the warp direction
ʽ
fw
is the warp direction strain caused by unit strain in the
fill direction
