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Steel Designers' Manual - 6th Edition (2003)
1158 Notes on section dimensions and properties
f
a
Definitions of all the individual terms are given in BS 5950-1 [1] , clause B.2.9.
The monosymmetry index (ya) is only applicable for unequal angles and is
calculated as follows:
y a
g
= È
2
Z
Î
Í AJ
Definitions of all the individual terms are given in BS 5950-1 [1] , Clause B.2.9.
3.3 Hollow sections
Section properties are given for both hot-finished and cold-formed hollow sections.
The ranges of hot-finished and cold-formed sections covered are different. The
section ranges listed are in line with sections that are readily available from the
major section manufacturers. For the same overall dimensions and wall thickness,
the section properties for hot-finished and cold-formed sections are different
because the corner radii are different.
3.3.1 Common properties
For comment on second moment of area, radius of gyration and elastic modulus,
see sections 3.2.1, 3.2.2 and 3.2.3.
For hot-finished square and rectangular hollow sections, the sectional properties
have been calculated, using corner radii of 1.5t externally and 1.0t internally, as
specified by BS EN 10210-2. [9]
For cold-formed square and rectangular hollow sections, the sectional properties
have been calculated, using the external corner radii of 2t if t £ 6 mm, 2.5t if 6 mm
< t £ 10 mm and 3t if t > 10mm as specified by BS EN 10219–2. [10] The internal corner
radii used are 1.0t if t £ 6 mm, 1.5t if 6 mm < t £ 10 mm and 2t if t > 10 mm, as specified
by BS EN 10219-2. [10]
3.3.2 Torsion constant (J)
For circular hollow sections:
J = 2I
u a
˘
˚
˙
È
= Í2v0
-
ÎÍ
05 .
Ú
For square and rectangular hollow sections:
2 3 4At
h th
J = +
h 3
( )
2 2 vi ut + vi dA˘1
˙
Iu˚˙t