SHS 400×400×8 vs CF SHS 400×400×8
SHS 400×400×8 is an SHS Hot-finished section from the UK Blue Book (SCI P363); CF SHS 400×400×8 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 1830 cm³ against 1800 cm³ of plastic modulus, a difference of 1.7%. They weigh essentially the same, 97.9 kg/m and 96.7 kg/m. Both are about 400 mm deep, so either fits the same construction zone.
| Property | SHS 400×400×8 SHS Hot-finished | CF SHS 400×400×8 SHS Cold-formed | Difference |
|---|---|---|---|
| Mass | 97.9 kg/m | 96.7 kg/m | +1.2% |
| Depth | 400 mm | 400 mm | same |
| Width | 400 mm | 400 mm | same |
| Web thickness | 0 mm | 0 mm | same |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 125 cm² | 123 cm² | +1.6% |
| Second moment, major (Iy) | 31,900 cm⁴ | 31,300 cm⁴ | +1.9% |
| Plastic modulus, major (Wpl,y) | 1,830 cm³ | 1,800 cm³ | +1.7% |
| Elastic modulus, major (Wel,y) | 1,590 cm³ | 1,560 cm³ | +1.9% |
| Second moment, minor (Iz) | 31,900 cm⁴ | 31,300 cm⁴ | +1.9% |
| Plastic modulus, minor (Wpl,z) | 1,830 cm³ | 1,800 cm³ | +1.7% |
| Radius of gyration, minor (iz) | 16 cm | 15.9 cm | +0.6% |
| Torsion constant (It) | 48,700 cm⁴ | 48,900 cm⁴ | -0.4% |
SHS 400×400×8 to BS EN 10210-2:2006; CF SHS 400×400×8 to BS EN 10219-2:2006. Difference is expressed relative to CF SHS 400×400×8.
How to choose between them
On stiffness, SHS 400×400×8 has the larger second moment of area: 31,900 cm⁴ against 31,300 cm⁴, a difference of 1.9%. 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 (18.7 against 18.6 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.