W 33X263 vs HE 900 x 391
W 33X263 is an W section from the American AISC Shapes Database; HE 900 x 391 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 17042.5 cm³ against 17000 cm³ of plastic modulus, a difference of 0.3%. They weigh essentially the same, 391.4 kg/m and 391 kg/m. HE 900 x 391 is deeper, 922 mm against 876.3 mm, which matters where the floor zone is tight.
| Property | W 33X263 W | HE 900 x 391 HE | Difference |
|---|---|---|---|
| Mass | 391.4 kg/m | 391 kg/m | +0.1% |
| Depth | 876.3 mm | 922 mm | -5.0% |
| Width | 401.3 mm | 307 mm | +30.7% |
| Web thickness | 22.1 mm | 25 mm | -11.6% |
| Flange thickness | 39.9 mm | 46 mm | -13.3% |
| Area | 499.4 cm² | 498 cm² | +0.3% |
| Second moment, major (Iy) | 661,808 cm⁴ | 674,000 cm⁴ | -1.8% |
| Plastic modulus, major (Wpl,y) | 17,042.5 cm³ | 17,000 cm³ | +0.3% |
| Elastic modulus, major (Wel,y) | 15,059.7 cm³ | 14,600 cm³ | +3.1% |
| Second moment, minor (Iz) | 43,288 cm⁴ | 22,300 cm⁴ | +94.1% |
| Plastic modulus, minor (Wpl,z) | 3,310.2 cm³ | 2,310 cm³ | +43.3% |
| Radius of gyration, minor (iz) | 9.3 cm | 6.7 cm | +38.8% |
| Torsion constant (It) | 2,027 cm⁴ | 2,600 cm⁴ | -22.0% |
W 33X263 to AISC Shapes Database v16.0; HE 900 x 391 to EN 10365 · Continental Steel. Difference is expressed relative to HE 900 x 391.
How to choose between them
On stiffness, HE 900 x 391 has the larger second moment of area: 674,000 cm⁴ against 661,808 cm⁴, a difference of 1.8%. 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 (43.5 against 43.5 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.
The two diverge much more about the minor axis: W 33X263 has 3310.2 cm³ of minor-axis plastic modulus against 2310 cm³, 43.3% 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. W sections are specified to AISC Shapes Database v16.0 and HE to EN 10365 · 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.