W 16X50 vs IPE O 400
W 16X50 is an W section from the American AISC Shapes Database; IPE O 400 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 1507.6 cm³ against 1500 cm³ of plastic modulus, a difference of 0.5%. They weigh essentially the same, 74.4 kg/m and 75.7 kg/m. W 16X50 is deeper, 414 mm against 404 mm, which matters where the floor zone is tight.
| Property | W 16X50 W | IPE O 400 IPE | Difference |
|---|---|---|---|
| Mass | 74.4 kg/m | 75.7 kg/m | -1.7% |
| Depth | 414 mm | 404 mm | +2.5% |
| Width | 179.6 mm | 182 mm | -1.3% |
| Web thickness | 9.7 mm | 9.7 mm | same |
| Flange thickness | 16 mm | 15.5 mm | +3.2% |
| Area | 94.8 cm² | 96.4 cm² | -1.7% |
| Second moment, major (Iy) | 27,430 cm⁴ | 26,800 cm⁴ | +2.4% |
| Plastic modulus, major (Wpl,y) | 1,507.6 cm³ | 1,500 cm³ | +0.5% |
| Elastic modulus, major (Wel,y) | 1,327.4 cm³ | 1,320 cm³ | +0.6% |
| Second moment, minor (Iz) | 1,548 cm⁴ | 1,560 cm⁴ | -0.8% |
| Plastic modulus, minor (Wpl,z) | 267.11 cm³ | 269 cm³ | -0.7% |
| Radius of gyration, minor (iz) | 4.04 cm | 4.03 cm | +0.2% |
| Torsion constant (It) | 63.27 cm⁴ | 73.3 cm⁴ | -13.7% |
W 16X50 to AISC Shapes Database v16.0; IPE O 400 to EN 10365 · Continental Steel. Difference is expressed relative to IPE O 400.
How to choose between them
On stiffness, W 16X50 has the larger second moment of area: 27,430 cm⁴ against 26,800 cm⁴, a difference of 2.4%. 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 16X50 is the more efficient section: 20.3 against 19.8 cm³ per kg/m, 2.3% 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 IPE 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.