Civil Engineering Reference
In-Depth Information
000634933
p
528515455
10
22
+5
425707933
10
20
M
cr
¼
0
:
5
:
:
M
cr
¼
150,021,280Nmm
¼
150,021
:
2kNm
We can now check the safety against lateral torsional buckling following
the rules specified in EC3 [1.27, 2.11] as follows:
M
Ed
M
b
,
Rd
1
:
0
Given:
M
Ed
¼
20, 285.7kNm,
W
y
¼
96, 417.7 cm
3
f
y
g
M1
M
b
,
Rd
¼w
LT
W
y
s
W
y
f
y
M
cr
r
26,514
:
9
l
LT
¼
¼
¼
0
:
42
150,021
:
2
h
i
+
l
2
l
LT
0
Þ
+0
:
42
2
F
LT
¼
0
:
51+
a
LT
:
¼
0
:
51+0
:
76 0
:
42
0
:
2
ð
2
LT
¼
0
:
672
1
w
LT
¼
q
F
LT
l
LT
but
w
LT
1
:
0
F
LT
+
1
w
LT
¼
672 +
p
but
w
LT
1
:
0
672
2
42
2
0
:
0
:
0
:
w
LT
¼
0
:
836
0
:
836
26,514
:
9
M
b
,
Rd
¼
¼
22,166
:
5kNm
>
20,285
:
7kNm
1
:
0
4.5.7 Design of Web Stiffeners
There are two types of stiffeners used to strengthen the thin web plate of the
main 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 stability
stiffeners (intermediate transverse stiffeners). The design of the stiffeners
can be performed as follows:
4.5.7.1 Load Bearing Stiffeners
To design the load bearing stiffener at supports (see
Figure 4.148
)
, 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
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