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CF RHS 300×200×6.3 - Section Properties

The CF RHS 300×200×6.3 is a rectangular hollow section with a mass of 47.1 kg/m, an overall depth of 300 mm and width of 200 mm and a wall thickness of 6.3 mm. It has a cross-sectional area of 60 cm², a second moment of area Iᵧ of 7620 cm⁴, a plastic modulus Wₚₗ,ᵧ of 610 cm³, tabulated by CivilAxis from BS EN 10219-2:2006 (SCI P363 Blue Book).

Mass
47.1 kg/m
Depth
300 mm
Width
200 mm
Wall thickness
6.3 mm
Area
60 cm²
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RHS Cold-formed section profile showing the dimension symbols used for CF RHS 300×200×6.3

Dimension symbols for RHS Cold-formed sections. Not to scale.

CF RHS 300×200×6.3 section properties to BS EN 10219-2:2006.

Geometry

Depth of sectionh300
Width of sectionb200
Wall thicknesst6.3

Mass and area

Mass per metremass47.1
Cross-sectional areaA60

Bending about the major axis (y-y)

Area moment of inertia about y-axisIy7620
Elastic section modulus about y-axisWel,y508
Plastic section modulus about y-axisWpl,y610
Radius of gyration about y-axisiy11.3

Bending about the minor axis (z-z)

Area moment of inertia about z-axisIz4100
Elastic section modulus about z-axisWel,z410
Plastic section modulus about z-axisWpl,z463
Radius of gyration about z-axisiz8.27

Torsion and warping

Torsion constant (St Venant)It8520
Section modulus for torsionWt680

Classification and stability

Flange local-buckling ratiocf/tf28.7
Web local-buckling ratiocw/tw44.6

Surface area

Surface area per metreSA/m0.973
Surface area per tonneSA/t20.6m²/t

Is CF RHS 300×200×6.3 strong enough?

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

✅Passes - 60% utilised, deflection governs
Bending30%
64.1 / 216.6 kNm
Shear6%
42.8 / 737.9 kN
Deflection60%
10.0 / 16.7 mm

Class 2 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 CF RHS 300×200×6.3

CF RHS 300×200×6.3 has a mass of 47.1 kg/m, tabulated to BS EN 10219-2:2006. A 12 m length therefore weighs about 565 kg, which is the figure to use for a steel take-off or when checking a lift.

CF RHS 300×200×6.3 has a depth of 300 mm, a width of 200 mm, a wall thickness of 6.3 mm, with a cross-sectional area of 60 cm². These are the nominal dimensions from BS EN 10219-2:2006; rolling tolerances apply to the delivered section.

The plastic section modulus about the major axis, Wpl,y, is 610 cm³, and the elastic modulus Wel,y is 508 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 217 kNm before any stability check.

The second moment of area about the major axis, Iy, is 7,620 cm⁴, and about the minor axis Iz is 4,100 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 = 28.7 for the flange and cw/tw = 44.6 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 11.3 cm about the major axis and iz is 8.27 cm about the minor axis. Column buckling is governed by the SMALLER value: the slenderness is lambda = L_cr / i, so with iz = 8.27 cm a 0.8 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 8,520 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 Cold-formed sizes

CF RHS 250×150×12.5CF RHS 300×100×8CF RHS 300×100×10CF RHS 300×200×6CF RHS 300×200×8CF RHS 300×200×10CF RHS 300×200×12CF RHS 300×200×12.5

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