C 12X30 vs PFC 300×90
C 12X30 is an C section from the American AISC Shapes Database; PFC 300×90 is the closest equivalent in the European (Continental) range. PFC 300×90 carries more bending: 568 cm³ of plastic modulus against 553.88 cm³, 2.5% more. PFC 300×90 is the lighter of the two at 41.4 kg/m against 44.6 kg/m, a saving of 7.7% on steel weight. Both are about 302 mm deep, so either fits the same construction zone.
| Property | C 12X30 C | PFC 300×90 PFC | Difference |
|---|---|---|---|
| Mass | 44.6 kg/m | 41.4 kg/m | +7.7% |
| Depth | 304.8 mm | 300 mm | +1.6% |
| Width | 80.5 mm | 90 mm | -10.6% |
| Web thickness | 13 mm | 9 mm | +44.4% |
| Flange thickness | 12.7 mm | 15.5 mm | -18.1% |
| Area | 56.8 cm² | 52.7 cm² | +7.8% |
| Second moment, major (Iy) | 6,743 cm⁴ | 7,218 cm⁴ | -6.6% |
| Plastic modulus, major (Wpl,y) | 553.88 cm³ | 568 cm³ | -2.5% |
| Elastic modulus, major (Wel,y) | 442.45 cm³ | 481 cm³ | -8.0% |
| Second moment, minor (Iz) | 213.1 cm⁴ | 404 cm⁴ | -47.3% |
| Plastic modulus, minor (Wpl,z) | 70.792 cm³ | 114 cm³ | -37.9% |
| Radius of gyration, minor (iz) | 1.94 cm | 2.77 cm | -30.0% |
| Torsion constant (It) | 35.84 cm⁴ | 28.8 cm⁴ | +24.4% |
C 12X30 to AISC Shapes Database v16.0; PFC 300×90 to Continental Steel. Difference is expressed relative to PFC 300×90.
How to choose between them
On stiffness, PFC 300×90 has the larger second moment of area: 7,218 cm⁴ against 6,743 cm⁴, a difference of 6.6%. 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 300×90 is the more efficient section: 13.7 against 12.4 cm³ per kg/m, 9.5% 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 300×90 has 114 cm³ of minor-axis plastic modulus against 70.792 cm³, 37.9% 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 7.7% weight.
In short, PFC 300×90 is the stronger section and PFC 300×90 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.