W 18X46 vs IPE A 450
W 18X46 is an W section from the American AISC Shapes Database; IPE A 450 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 1486.3 cm³ against 1490 cm³ of plastic modulus, a difference of 0.2%. They weigh essentially the same, 68.5 kg/m and 67.2 kg/m. W 18X46 is deeper, 459.7 mm against 447 mm, which matters where the floor zone is tight.
| Property | W 18X46 W | IPE A 450 IPE | Difference |
|---|---|---|---|
| Mass | 68.5 kg/m | 67.2 kg/m | +1.9% |
| Depth | 459.7 mm | 447 mm | +2.8% |
| Width | 153.9 mm | 190 mm | -19.0% |
| Web thickness | 9.1 mm | 7.6 mm | +19.7% |
| Flange thickness | 15.4 mm | 13.1 mm | +17.6% |
| Area | 87.1 cm² | 85.6 cm² | +1.8% |
| Second moment, major (Iy) | 29,636 cm⁴ | 29,800 cm⁴ | -0.6% |
| Plastic modulus, major (Wpl,y) | 1,486.3 cm³ | 1,490 cm³ | -0.2% |
| Elastic modulus, major (Wel,y) | 1,291.3 cm³ | 1,330 cm³ | -2.9% |
| Second moment, minor (Iz) | 936.5 cm⁴ | 1,500 cm⁴ | -37.6% |
| Plastic modulus, minor (Wpl,z) | 191.73 cm³ | 246 cm³ | -22.1% |
| Radius of gyration, minor (iz) | 3.28 cm | 4.19 cm | -21.7% |
| Torsion constant (It) | 50.78 cm⁴ | 47.1 cm⁴ | +7.8% |
W 18X46 to AISC Shapes Database v16.0; IPE A 450 to EN 10365 · Continental Steel. Difference is expressed relative to IPE A 450.
How to choose between them
On stiffness, IPE A 450 has the larger second moment of area: 29,800 cm⁴ against 29,636 cm⁴, a difference of 0.6%. 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, IPE A 450 is the more efficient section: 22.2 against 21.7 cm³ per kg/m, 2.1% 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: IPE A 450 has 246 cm³ of minor-axis plastic modulus against 191.73 cm³, 22.1% 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 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.