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RHS 300×250×16 - Section Properties

The RHS 300×250×16 is a rectangular hollow section with a mass of 128 kg/m, an overall depth of 300 mm and width of 250 mm and a wall thickness of 16 mm. It has a cross-sectional area of 163 cm², a second moment of area Iᵧ of 20600 cm⁴, a plastic modulus Wₚₗ,ᵧ of 1670 cm³, tabulated by CivilAxis from BS EN 10210-2:2006 (SCI P363 Blue Book).

Mass
128 kg/m
Depth
300 mm
Width
250 mm
Wall thickness
16 mm
Area
163 cm²
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RHS Hot-finished section profile showing the dimension symbols used for RHS 300×250×16

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

RHS 300×250×16 section properties to BS EN 10210-2:2006.

Geometry

Depth of sectionh300
Width of sectionb250
Wall thicknesst16

Mass and area

Mass per metremass128
Cross-sectional areaA163

Bending about the major axis (y-y)

Area moment of inertia about y-axisIy20600
Elastic section modulus about y-axisWel,y1380
Plastic section modulus about y-axisWpl,y1670
Radius of gyration about y-axisiy11.2

Bending about the minor axis (z-z)

Area moment of inertia about z-axisIz15500
Elastic section modulus about z-axisWel,z1240
Plastic section modulus about z-axisWpl,z1470
Radius of gyration about z-axisiz9.74

Torsion and warping

Torsion constant (St Venant)It28100
Section modulus for torsionWt1900

Classification and stability

Flange local-buckling ratiocf/tf12.6
Web local-buckling ratiocw/tw15.8

Surface area

Surface area per metreSA/m1.06
Surface area per tonneSA/t8.28m²/t

Is RHS 300×250×16 strong enough?

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

✅Passes - 61% utilised, deflection governs
Bending30%
175.5 / 592.9 kNm
Shear6%
117.0 / 1822.3 kN
Deflection61%
10.1 / 16.7 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 300×250×16

RHS 300×250×16 has a mass of 128 kg/m, tabulated to BS EN 10210-2:2006. A 12 m length therefore weighs about 1536 kg, which is the figure to use for a steel take-off or when checking a lift.

RHS 300×250×16 has a depth of 300 mm, a width of 250 mm, a wall thickness of 16 mm, with a cross-sectional area of 163 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 1,670 cm³, and the elastic modulus Wel,y is 1,380 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 593 kNm before any stability check.

The second moment of area about the major axis, Iy, is 20,600 cm⁴, and about the minor axis Iz is 15,500 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 = 12.6 for the flange and cw/tw = 15.8 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 11.2 cm about the major axis and iz is 9.74 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 9.74 cm a 1.0 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 28,100 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 300×250×8.8RHS 300×250×10RHS 300×250×12.5RHS 300×250×14.2RHS 340×100×10RHS 350×150×5RHS 350×150×6.3RHS 350×150×7.1

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