PFC 180×90×26 vs PFC 180×90
PFC 180×90×26 is a PFC section from the UK Blue Book (SCI P363); PFC 180×90 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 232 cm³ against 232 cm³ of plastic modulus, a difference of 0.0%. They weigh essentially the same, 26.1 kg/m and 26.1 kg/m. Both are about 180 mm deep, so either fits the same construction zone.
| Property | PFC 180×90×26 PFC | PFC 180×90 PFC | Difference |
|---|---|---|---|
| Mass | 26.1 kg/m | 26.1 kg/m | same |
| Depth | 180 mm | 180 mm | same |
| Width | 90 mm | 90 mm | same |
| Web thickness | 6.5 mm | 6.5 mm | same |
| Flange thickness | 12.5 mm | 12.5 mm | same |
| Area | 33.2 cm² | 33.2 cm² | same |
| Second moment, major (Iy) | 1,820 cm⁴ | 1,817 cm⁴ | +0.2% |
| Plastic modulus, major (Wpl,y) | 232 cm³ | 232 cm³ | same |
| Elastic modulus, major (Wel,y) | 202 cm³ | 202 cm³ | same |
| Second moment, minor (Iz) | 277 cm⁴ | 277 cm⁴ | same |
| Plastic modulus, minor (Wpl,z) | 83.5 cm³ | 83.5 cm³ | same |
| Radius of gyration, minor (iz) | 2.89 cm | 2.89 cm | same |
| Torsion constant (It) | 13.3 cm⁴ | 13.3 cm⁴ | same |
PFC 180×90×26 to BS EN 1993-1-1:2005 / BS 4-1:2005; PFC 180×90 to Continental Steel. Difference is expressed relative to PFC 180×90.
How to choose between them
On stiffness, PFC 180×90×26 has the larger second moment of area: 1,820 cm⁴ against 1,817 cm⁴, a difference of 0.2%. 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 (8.9 against 8.9 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.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. PFC sections are specified to BS EN 1993-1-1:2005 / BS 4-1:2005 and PFC to Continental Steel; the steel grades, tolerances and available lengths differ, connection details and bolt gauges are set out differently, and the two are rarely both stocked in the same market. Check availability before changing a section on a drawing to save a marginal amount of weight.
In short, these two are genuine equivalents. Pick whichever your supplier stocks and the rest of the frame already uses.