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RHS 250×150×7.1 - Section Properties

The RHS 250×150×7.1 is a rectangular hollow section with a mass of 42.6 kg/m, an overall depth of 250 mm and width of 150 mm and a wall thickness of 7.1 mm. It has a cross-sectional area of 54.2 cm², a second moment of area Iᵧ of 4610 cm⁴, a plastic modulus Wₚₗ,ᵧ of 449 cm³, tabulated by CivilAxis from BS EN 10210-2:2006 (SCI P363 Blue Book).

Mass
42.6 kg/m
Depth
250 mm
Width
150 mm
Wall thickness
7.1 mm
Area
54.2 cm²
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RHS Hot-finished section profile showing the dimension symbols used for RHS 250×150×7.1

Dimension symbols for RHS Hot-finished sections. Not to scale.

RHS 250×150×7.1 section properties to BS EN 10210-2:2006.

Geometry

Depth of sectionh250
Width of sectionb150
Wall thicknesst7.1

Mass and area

Mass per metremass42.6
Cross-sectional areaA54.2

Bending about the major axis (y-y)

Area moment of inertia about y-axisIy4610
Elastic section modulus about y-axisWel,y368
Plastic section modulus about y-axisWpl,y449
Radius of gyration about y-axisiy9.22

Bending about the minor axis (z-z)

Area moment of inertia about z-axisIz2080
Elastic section modulus about z-axisWel,z277
Plastic section modulus about z-axisWpl,z315
Radius of gyration about z-axisiz6.19

Torsion and warping

Torsion constant (St Venant)It4520
Section modulus for torsionWt457

Classification and stability

Flange local-buckling ratiocf/tf18.1
Web local-buckling ratiocw/tw32.2

Surface area

Surface area per metreSA/m0.782
Surface area per tonneSA/t18.4m²/t

Is RHS 250×150×7.1 strong enough?

Simply supported beam, uniform load, major-axis bending - to EN 1993-1-1.

✅Passes - 61% utilised, deflection governs
Bending29%
46.9 / 159.4 kNm
Shear5%
37.5 / 694.3 kN
Deflection61%
8.4 / 13.9 mm

Class 1 section. ULS uses γQ = 1.5 on the load you enter; deflection uses the unfactored load against L/360. Lateral-torsional buckling is not included - the compression flange is assumed restrained.

Common questions about RHS 250×150×7.1

RHS 250×150×7.1 has a mass of 42.6 kg/m, tabulated to BS EN 10210-2:2006. A 12 m length therefore weighs about 511 kg, which is the figure to use for a steel take-off or when checking a lift.

RHS 250×150×7.1 has a depth of 250 mm, a width of 150 mm, a wall thickness of 7.1 mm, with a cross-sectional area of 54.2 cm². These are the nominal dimensions from BS EN 10210-2:2006; rolling tolerances apply to the delivered section.

The plastic section modulus about the major axis, Wpl,y, is 449 cm³, and the elastic modulus Wel,y is 368 cm³. Wpl,y is what sets the moment capacity of a Class 1 or 2 section: M_pl,Rd = Wpl,y x f_y / gamma_M0, so at S355 with gamma_M0 = 1.0 this section reaches about 159 kNm before any stability check.

The second moment of area about the major axis, Iy, is 4,610 cm⁴, and about the minor axis Iz is 2,080 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.

Its local-buckling ratios are cf/tf = 18.1 for the flange and cw/tw = 32.2 for the web. EN 1993-1-1 Table 5.2 compares these against limits scaled by epsilon = sqrt(235/f_y), so the class depends on the steel grade as well as the geometry - the same section can be Class 1 in S275 and Class 3 in S355. Use the Capacity tab on this page for the classification at a specific grade.

iy is 9.22 cm about the major axis and iz is 6.19 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 6.19 cm a 0.6 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 4,520 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.

Related RHS Hot-finished sizes

RHS 250×100×14.2RHS 250×100×16RHS 250×150×5RHS 250×150×6.3RHS 250×150×8RHS 250×150×8.8RHS 250×150×10RHS 250×150×12.5

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