C 10X20 vs PFC 260×75
C 10X20 is an C section from the American AISC Shapes Database; PFC 260×75 is the closest equivalent in the European (Continental) range. PFC 260×75 carries more bending: 328 cm³ of plastic modulus against 317.91 cm³, 3.1% more. PFC 260×75 is the lighter of the two at 27.6 kg/m against 29.8 kg/m, a saving of 8.0% on steel weight. PFC 260×75 is deeper, 260 mm against 254 mm, which matters where the floor zone is tight.
| Property | C 10X20 C | PFC 260×75 PFC | Difference |
|---|---|---|---|
| Mass | 29.8 kg/m | 27.6 kg/m | +8.0% |
| Depth | 254 mm | 260 mm | -2.3% |
| Width | 69.6 mm | 75 mm | -7.2% |
| Web thickness | 9.6 mm | 7 mm | +37.1% |
| Flange thickness | 11.1 mm | 12 mm | -7.5% |
| Area | 37.9 cm² | 35.1 cm² | +8.0% |
| Second moment, major (Iy) | 3,284 cm⁴ | 3,619 cm⁴ | -9.3% |
| Plastic modulus, major (Wpl,y) | 317.91 cm³ | 328 cm³ | -3.1% |
| Elastic modulus, major (Wel,y) | 258.92 cm³ | 278 cm³ | -6.9% |
| Second moment, minor (Iz) | 116.5 cm⁴ | 185 cm⁴ | -37.0% |
| Plastic modulus, minor (Wpl,z) | 44.245 cm³ | 62 cm³ | -28.6% |
| Radius of gyration, minor (iz) | 1.75 cm | 2.3 cm | -23.9% |
| Torsion constant (It) | 15.32 cm⁴ | 11.7 cm⁴ | +30.9% |
C 10X20 to AISC Shapes Database v16.0; PFC 260×75 to Continental Steel. Difference is expressed relative to PFC 260×75.
How to choose between them
On stiffness, PFC 260×75 has the larger second moment of area: 3,619 cm⁴ against 3,284 cm⁴, a difference of 9.3%. 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, PFC 260×75 is the more efficient section: 11.9 against 10.7 cm³ per kg/m, 10.2% 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.
The two diverge much more about the minor axis: PFC 260×75 has 62 cm³ of minor-axis plastic modulus against 44.245 cm³, 28.6% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. C sections are specified to AISC Shapes Database v16.0 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 8.0% weight.
In short, PFC 260×75 is the stronger section and PFC 260×75 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.