The UA 30×20×4 is a unequal angle with a mass of 1.46 kg/m, an overall depth of 30 mm and width of 20 mm. It has a cross-sectional area of 1.86 cm², a second moment of area Iᵧ of 1.59 cm⁴, an elastic modulus Wₑₗ,ᵧ of 0.807 cm³, tabulated by CivilAxis from BS EN 1993-1-1:2005 / BS EN 10056-1:1999 (SCI P363 Blue Book).
Mass
1.46 kg/m
Depth
30 mm
Width
20 mm
Area
1.86 cm²
Ask about capacity, buckling or detailing for UA 30×20×4.
UA 30×20×4 section properties to BS EN 1993-1-1:2005 / BS EN 10056-1:1999.
Geometry
Depth of section
h
30
Width of section
b
20
Web thickness
tw
4
Flange thickness
tf
4
Root fillet radius
r
4
Toe radius
r2
2
Mass and area
Mass per metre
mass
1.46
Cross-sectional area
A
1.86
Bending about the major axis (y-y)
Area moment of inertia about y-axis
Iy
1.59
Elastic section modulus about y-axis
Wel,y
0.807
Radius of gyration about y-axis
iy
0.925
Bending about the minor axis (z-z)
Area moment of inertia about z-axis
Iz
0.553
Elastic section modulus about z-axis
Wel,z
0.379
Radius of gyration about z-axis
iz
0.546
Principal axes
Area moment of inertia about u-u (major principal) axis
Iu
1.81
Area moment of inertia about v-v (minor principal) axis
Iv
0.33
Radius of gyration about u-u axis
iu
0.988
Radius of gyration about v-v axis
iv
0.421
Elastic section modulus about u-u axis
Wel,u
0.807
Elastic section modulus about v-v axis
Wel,v
0.379
Torsion and warping
Torsion constant (St Venant)
It
0.1096
Detailing dimensions
Centroid distance from back of leg (y)
cy
1.03
Centroid distance from back of leg (z)
cz
0.541
Common questions about UA 30×20×4
UA 30×20×4 has a mass of 1.46 kg/m, tabulated to BS EN 1993-1-1:2005 / BS EN 10056-1:1999. A 12 m length therefore weighs about 18 kg, which is the figure to use for a steel take-off or when checking a lift.
UA 30×20×4 has a depth of 30 mm, a width of 20 mm, a web thickness of 4 mm, a flange thickness of 4 mm, with a cross-sectional area of 1.86 cm². These are the nominal dimensions from BS EN 1993-1-1:2005 / BS EN 10056-1:1999; rolling tolerances apply to the delivered section.
The elastic section modulus about the major axis, Wel,y, is 0.807 cm³. Angles are tabulated about their principal (u-u and v-v) axes rather than a plastic major-axis modulus, so the elastic value is the one to design from unless you are working from the principal-axis properties directly.
The second moment of area about the major axis, Iy, is 1.59 cm⁴, and about the minor axis Iz is 0.553 cm⁴. Iy is the value deflection depends on - for a simply supported beam under a uniform load, the midspan deflection is 5wL⁴/384EIy - so on spans where a deflection limit governs rather than strength, this is the number that decides the section.
iy is 0.925 cm about the major axis and iz is 0.546 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 0.546 cm a 0.1 m effective length already gives lambda = 100. Minor-axis buckling almost always controls unless the weak axis is restrained.
The St Venant torsion constant It is 0.11 cm⁴. Closed sections carry torsion in a shear flow around the perimeter, which makes them far stiffer in torsion than an open section of the same weight and is usually why one is specified.
