The UA 125×75×8 is a unequal angle with a mass of 12.2 kg/m, an overall depth of 125 mm and width of 75 mm. It has a cross-sectional area of 15.5 cm², a second moment of area Iᵧ of 247 cm⁴, an elastic modulus Wₑₗ,ᵧ of 29.6 cm³, tabulated by CivilAxis from BS EN 1993-1-1:2005 / BS EN 10056-1:1999 (SCI P363 Blue Book).
Mass
12.2 kg/m
Depth
125 mm
Width
75 mm
Area
15.5 cm²
Ask about capacity, buckling or detailing for UA 125×75×8.
UA 125×75×8 section properties to BS EN 1993-1-1:2005 / BS EN 10056-1:1999.
Geometry
Depth of section
h
125
Width of section
b
75
Web thickness
tw
8
Flange thickness
tf
8
Root fillet radius
r
11
Toe radius
r2
5.5
Mass and area
Mass per metre
mass
12.2
Cross-sectional area
A
15.5
Bending about the major axis (y-y)
Area moment of inertia about y-axis
Iy
247
Elastic section modulus about y-axis
Wel,y
29.6
Radius of gyration about y-axis
iy
4
Bending about the minor axis (z-z)
Area moment of inertia about z-axis
Iz
67.6
Elastic section modulus about z-axis
Wel,z
11.6
Radius of gyration about z-axis
iz
2.09
Principal axes
Area moment of inertia about u-u (major principal) axis
Iu
274
Area moment of inertia about v-v (minor principal) axis
Iv
40.9
Radius of gyration about u-u axis
iu
4.21
Radius of gyration about v-v axis
iv
1.63
Elastic section modulus about u-u axis
Wel,u
29.6
Elastic section modulus about v-v axis
Wel,v
11.6
Torsion and warping
Torsion constant (St Venant)
It
3.62
Detailing dimensions
Centroid distance from back of leg (y)
cy
4.14
Centroid distance from back of leg (z)
cz
1.68
Common questions about UA 125×75×8
UA 125×75×8 has a mass of 12.2 kg/m, tabulated to BS EN 1993-1-1:2005 / BS EN 10056-1:1999. A 12 m length therefore weighs about 146 kg, which is the figure to use for a steel take-off or when checking a lift.
UA 125×75×8 has a depth of 125 mm, a width of 75 mm, a web thickness of 8 mm, a flange thickness of 8 mm, with a cross-sectional area of 15.5 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 29.6 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 247 cm⁴, and about the minor axis Iz is 67.6 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 4 cm about the major axis and iz is 2.09 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 2.09 cm a 0.2 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 3.62 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.
