W 36X256 vs HE 900 x 391
W 36X256 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%. W 36X256 is the lighter of the two at 381 kg/m against 391 kg/m, a saving of 2.6% on steel weight. W 36X256 is deeper, 950 mm against 922 mm, which matters where the floor zone is tight.
| Property | W 36X256 W | HE 900 x 391 HE | Difference |
|---|---|---|---|
| Mass | 381 kg/m | 391 kg/m | -2.6% |
| Depth | 950 mm | 922 mm | +3.0% |
| Width | 309.9 mm | 307 mm | +0.9% |
| Web thickness | 24.4 mm | 25 mm | -2.4% |
| Flange thickness | 43.9 mm | 46 mm | -4.6% |
| Area | 485.8 cm² | 498 cm² | -2.4% |
| Second moment, major (Iy) | 699,269 cm⁴ | 674,000 cm⁴ | +3.7% |
| Plastic modulus, major (Wpl,y) | 17,042.5 cm³ | 17,000 cm³ | +0.3% |
| Elastic modulus, major (Wel,y) | 14,666.4 cm³ | 14,600 cm³ | +0.5% |
| Second moment, minor (Iz) | 21,977 cm⁴ | 22,300 cm⁴ | -1.4% |
| Plastic modulus, minor (Wpl,z) | 2,245 cm³ | 2,310 cm³ | -2.8% |
| Radius of gyration, minor (iz) | 6.73 cm | 6.7 cm | +0.4% |
| Torsion constant (It) | 2,202 cm⁴ | 2,600 cm⁴ | -15.3% |
W 36X256 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, W 36X256 has the larger second moment of area: 699,269 cm⁴ against 674,000 cm⁴, a difference of 3.7%. 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, W 36X256 is the more efficient section: 44.7 against 43.5 cm³ per kg/m, 2.9% 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.
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 2.6% weight.
In short, W 36X256 is the stronger section and W 36X256 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.