W 33X221 vs HE 900 M
W 33X221 is an W section from the American AISC Shapes Database; HE 900 M is the closest equivalent in the European (Continental) range. HE 900 M carries more bending: 14400 cm³ of plastic modulus against 14043.7 cm³, 2.5% more. They weigh essentially the same, 328.9 kg/m and 333 kg/m. HE 900 M is deeper, 910 mm against 861.1 mm, which matters where the floor zone is tight.
| Property | W 33X221 W | HE 900 M HE | Difference |
|---|---|---|---|
| Mass | 328.9 kg/m | 333 kg/m | -1.2% |
| Depth | 861.1 mm | 910 mm | -5.4% |
| Width | 401.3 mm | 302 mm | +32.9% |
| Web thickness | 19.7 mm | 21 mm | -6.2% |
| Flange thickness | 32.5 mm | 40 mm | -18.8% |
| Area | 421.3 cm² | 424 cm² | -0.6% |
| Second moment, major (Iy) | 536,939 cm⁴ | 570,000 cm⁴ | -5.8% |
| Plastic modulus, major (Wpl,y) | 14,043.7 cm³ | 14,400 cm³ | -2.5% |
| Elastic modulus, major (Wel,y) | 12,437.8 cm³ | 12,500 cm³ | -0.5% |
| Second moment, minor (Iz) | 34,963 cm⁴ | 18,400 cm⁴ | +90.0% |
| Plastic modulus, minor (Wpl,z) | 2,687.5 cm³ | 1,930 cm³ | +39.2% |
| Radius of gyration, minor (iz) | 9.12 cm | 6.6 cm | +38.2% |
| Torsion constant (It) | 1,157 cm⁴ | 1,680 cm⁴ | -31.1% |
W 33X221 to AISC Shapes Database v16.0; HE 900 M to EN 10365 · Continental Steel. Difference is expressed relative to HE 900 M.
How to choose between them
On stiffness, HE 900 M has the larger second moment of area: 570,000 cm⁴ against 536,939 cm⁴, a difference of 5.8%. 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 (42.7 against 43.2 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 33X221 has 2687.5 cm³ of minor-axis plastic modulus against 1930 cm³, 39.2% 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, HE 900 M is the stronger section and W 33X221 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.