Civil Engineering Reference
In-Depth Information
b
/
t
of every element of the cross-section satisfies
b
t
≤
λ
3
ε
(4.50)
where
λ
3
ε
is the appropriate Class 3 slenderness limit of Table 5.2 of EC3 and
ε
is a constant given by
ε
=
235
/
f
y
(4.51)
in which
f
y
is in N/mm
2
units. Some values of
λ
3
ε
are given in Figures 4.27
and 4.28.
Class4cross-sectionsarethosecontainingatleastoneslenderelementforwhich
equation 4.50 is not satisfied. For these, the effective area is reduced to
A
eff
=
A
c
,
eff
(4.52)
in which
A
c
,
eff
is the effective area of a flat compression element comprising the
cross-section, which is obtained from its gross area
A
c
by
A
c
,
eff
=
ρ
A
c
(4.53)
where
ρ
is a reduction factor given by
ρ
=
(
λ
p
−
0.22
)/λ
p
≤
1.0
(4.54)
Section description UB, UC CHS Box RHS
d
0
b
1
b
1
b
2
b
1
Section and
element widths
b
2
d
1
d
1
d
1
-
-
Flange outstand
b
1
14
14
-
-
Flange
b
2
supported
along both edges
Web
d
1
supported
42
42
-
42
42
42
along both edges
-
-
-
Diameter
d
0
90
2
Figure 4.27
Yield limits for some compression elements.
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