CHS 457×8 vs CF CHS 457×8
CHS 457×8 is an CHS Hot-finished section from the UK Blue Book (SCI P363); CF CHS 457×8 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 1610 cm³ against 1610 cm³ of plastic modulus, a difference of 0.0%. They weigh essentially the same, 88.6 kg/m and 88.6 kg/m. Both are about 457 mm deep, so either fits the same construction zone.
| Property | CHS 457×8 CHS Hot-finished | CF CHS 457×8 CHS Cold-formed | Difference |
|---|---|---|---|
| Mass | 88.6 kg/m | 88.6 kg/m | same |
| Depth | 457 mm | 457 mm | same |
| Width | 457 mm | 457 mm | same |
| Web thickness | 0 mm | 0 mm | same |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 113 cm² | 113 cm² | same |
| Second moment, major (Iy) | 28,400 cm⁴ | 28,400 cm⁴ | same |
| Plastic modulus, major (Wpl,y) | 1,610 cm³ | 1,610 cm³ | same |
| Elastic modulus, major (Wel,y) | 1,250 cm³ | 1,250 cm³ | same |
| Second moment, minor (Iz) | 28,400 cm⁴ | 28,400 cm⁴ | same |
| Plastic modulus, minor (Wpl,z) | 1,610 cm³ | 1,610 cm³ | same |
| Radius of gyration, minor (iz) | 15.9 cm | 15.9 cm | same |
| Torsion constant (It) | 56,900 cm⁴ | 56,900 cm⁴ | same |
CHS 457×8 to BS EN 10210-2:2006; CF CHS 457×8 to BS EN 10219-2:2006. Difference is expressed relative to CF CHS 457×8.
How to choose between them
On stiffness, CF CHS 457×8 has the larger second moment of area: 28,400 cm⁴ against 28,400 cm⁴, a difference of 0.0%. 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, the two are equally efficient (18.2 against 18.2 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
In short, these two are genuine equivalents. Pick whichever your supplier stocks and the rest of the frame already uses.