IPE 450 vs W 18X50
IPE 450 is an IPE section from the European (Continental) range; W 18X50 is the closest equivalent in the American AISC Shapes Database. IPE 450 carries more bending: 1700 cm³ of plastic modulus against 1655.1 cm³, 2.7% more. W 18X50 is the lighter of the two at 74.4 kg/m against 77.6 kg/m, a saving of 4.3% on steel weight. Both are about 454 mm deep, so either fits the same construction zone.
| Property | IPE 450 IPE | W 18X50 W | Difference |
|---|---|---|---|
| Mass | 77.6 kg/m | 74.4 kg/m | +4.3% |
| Depth | 450 mm | 457.2 mm | -1.6% |
| Width | 190 mm | 190.5 mm | -0.3% |
| Web thickness | 9.4 mm | 9 mm | +4.4% |
| Flange thickness | 14.6 mm | 14.5 mm | +0.7% |
| Area | 98.8 cm² | 94.8 cm² | +4.2% |
| Second moment, major (Iy) | 33,700 cm⁴ | 33,299 cm⁴ | +1.2% |
| Plastic modulus, major (Wpl,y) | 1,700 cm³ | 1,655.1 cm³ | +2.7% |
| Elastic modulus, major (Wel,y) | 1,500 cm³ | 1,456.8 cm³ | +3.0% |
| Second moment, minor (Iz) | 1,680 cm⁴ | 1,669 cm⁴ | +0.7% |
| Plastic modulus, minor (Wpl,z) | 276 cm³ | 272.03 cm³ | +1.5% |
| Radius of gyration, minor (iz) | 4.12 cm | 4.19 cm | -1.7% |
| Torsion constant (It) | 66.7 cm⁴ | 51.61 cm⁴ | +29.2% |
IPE 450 to EN 10365 · Continental Steel; W 18X50 to AISC Shapes Database v16.0. Difference is expressed relative to W 18X50.
How to choose between them
On stiffness, IPE 450 has the larger second moment of area: 33,700 cm⁴ against 33,299 cm⁴, a difference of 1.2%. 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 (21.9 against 22.2 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.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. IPE sections are specified to EN 10365 · Continental Steel and W to AISC Shapes Database v16.0; 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 4.3% weight.
In short, IPE 450 is the stronger section and W 18X50 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.