RHS 300×100×10 vs CF RHS 300×100×10
RHS 300×100×10 is an RHS Hot-finished section from the UK Blue Book (SCI P363); CF RHS 300×100×10 is the closest equivalent in the UK Blue Book (SCI P363). RHS 300×100×10 carries more bending: 666 cm³ of plastic modulus against 631 cm³, 5.5% more. CF RHS 300×100×10 is the lighter of the two at 57 kg/m against 58.8 kg/m, a saving of 3.2% on steel weight. Both are about 300 mm deep, so either fits the same construction zone.
| Property | RHS 300×100×10 RHS Hot-finished | CF RHS 300×100×10 RHS Cold-formed | Difference |
|---|---|---|---|
| Mass | 58.8 kg/m | 57 kg/m | +3.2% |
| Depth | 300 mm | 300 mm | same |
| Width | 100 mm | 100 mm | same |
| Web thickness | 0 mm | 0 mm | same |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 74.9 cm² | 72.6 cm² | +3.2% |
| Second moment, major (Iy) | 7,610 cm⁴ | 7,110 cm⁴ | +7.0% |
| Plastic modulus, major (Wpl,y) | 666 cm³ | 631 cm³ | +5.5% |
| Elastic modulus, major (Wel,y) | 508 cm³ | 474 cm³ | +7.2% |
| Second moment, minor (Iz) | 1,280 cm⁴ | 1,220 cm⁴ | +4.9% |
| Plastic modulus, minor (Wpl,z) | 296 cm³ | 285 cm³ | +3.9% |
| Radius of gyration, minor (iz) | 4.13 cm | 4.11 cm | +0.5% |
| Torsion constant (It) | 3,680 cm⁴ | 3,680 cm⁴ | same |
RHS 300×100×10 to BS EN 10210-2:2006; CF RHS 300×100×10 to BS EN 10219-2:2006. Difference is expressed relative to CF RHS 300×100×10.
How to choose between them
On stiffness, RHS 300×100×10 has the larger second moment of area: 7,610 cm⁴ against 7,110 cm⁴, a difference of 7.0%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram of steel, RHS 300×100×10 is the more efficient section: 11.3 against 11.1 cm³ per kg/m, 2.3% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
In short, RHS 300×100×10 is the stronger section and CF RHS 300×100×10 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.