Civil Engineering Reference
In-Depth Information
Effective flange area.
k
σ
,
f
=
0.43
EC3-1-5T4.2
λ
p
,
f
=
(
400
/
2
−
10
/
2
−
8
)/
10
28.4
×
0.814
×
√
0.43
=
1.23
>
0.748
EC3-1-5 4.4(2)
ρ
f
=
(
1.23
−
0.188
)/
1.23
2
=
0.687
EC3-1-5 4.4(2)
A
eff
,
f
=
0.687
×
4
×
(
400
/
2
−
10
/
2
−
8
)
×
10
+
(
10
+
2
×
8
)
×
10
×
2
EC3-1-5 4.4(1)
=
5658 mm
2
Effective web area.
k
σ
,
w
=
4.0
EC3-1-5T4.1
λ
p
,
w
=
(
420
−
2
×
10
−
2
×
8
)/
10
28.4
×
0.814
×
√
=
0.831
>
0.673
EC3-1-5 4.4(2)
4.0
ρ
w
={
0.831
−
0.055
×
(
3
+
1
)
}
/
0.831
2
=
0.885
EC3-1-5 4.4(2)
A
eff
,
w
=
0.885
×
(
420
−
2
×
10
−
2
×
8
)
×
(
10
+
8
×
10
×
2
)
=
3558 mm
2
EC3-1-5 4.4(1)
Compression resistance.
A
eff
=
5658
+
3558
=
9216 mm
2
N
c
,
Rd
=
9216
×
355
/
1.0 N
=
3272 kN.
4.9.2 Example 2 - section moment resistance of a
Class 3 I-beam
Problem.
Determinethesectionmomentresistanceandexaminethesuitabilityfor
plastic design of the 356
×
171 UB 45 of S355 steel shown in Figure 4.31b.
Classifying the section-plate elements.
t
f
=
9.7 mm,
t
w
=
7.0 mm,
f
y
=
355 N
/
mm
2
EN10025-2
ε
=
√
(
235
/
355
)
=
0.814
T5.2
c
f
/(
t
f
ε)
=
(
171.1
/
2
−
7.0
/
2
−
10.2
)/(
9.7
×
0.814
)
T5.2
=
9.1
>
9 but
<
10, and so the flange is Class 2.
T5.2
c
w
/(
t
w
ε)
=
(
351.4
−
2
×
9.7
−
2
×
10.2
)/(
7.0
×
0.814
)
T5.2
=
54.7
<
72 and so the web is Class 1.
T5.2
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