Civil Engineering Reference
In-Depth Information
The axial compressive force in the diagonal bracing member
(
N
Ed
¼
332.6 kN):
N
Ed
N
b
,
Rd
1
:
0
wAf
y
g
M1
where
N
b
,
Rd
¼
4cm
2
A¼
2
19
:
2
¼
38
:
1
F
+
w¼
p
but
w
1
:
0
l
2
F
2
h
i
+
l
2
51+
a l
0
F¼
0
:
:
2
¼
1
478
2
F¼
0
:
51+0
:
34 1
ð
:
478
0
:
2
Þ
+1
:
:
81
1
81 +
p
w¼
¼
0
:
35 but
w
1
:
0
81
2
478
2
1
:
1
:
1
:
:
35
38
:
4
100
275
1
:
1
0
Then,
N
b
,
Rd
¼
¼
336,000
N
b
,
Rd
¼
336 kN
>
N
Ed
¼
332
:
6 kN Then O
ð
:
K
:
Þ
4.4.4 Design of Web Stiffeners
There are two types of stiffeners used to strengthen the thin web plate of the
main composite plate girder against buckling due to shear stresses, bending
stresses, or both. The stiffeners at the supports are commonly known as load
bearing stiffeners, while intermediate stiffeners are commonly known as sta-
bility stiffeners (intermediate transverse stiffeners). The design of the stiff-
eners can be performed as follows:
4.4.4.1 Load Bearing Stiffeners
To design the load bearing stiffener at supports (see
Figure 4.120
)
, we can
also follow the design rules specified in EC3 [1.27, 2.11] for concentrically
loaded compression members. The axial force in the stiffener is the maxi-
mum reaction at
supports
(
N
Ed
¼R
D+L+
F
), which is
equal
to
2193.36 kN. The design procedures can be performed as follows:
N
Ed
N
b
,
Rd
1
:
0
wAf
y
g
M1
where
N
b
,
Rd
¼
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