IPE 450 vs S 18X54.7
IPE 450 is an IPE section from the European (Continental) range; S 18X54.7 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 1700 cm³ against 1704.3 cm³ of plastic modulus, a difference of 0.3%. IPE 450 is the lighter of the two at 77.6 kg/m against 81.4 kg/m, a saving of 4.7% on steel weight. Both are about 454 mm deep, so either fits the same construction zone.
| Property | IPE 450 IPE | S 18X54.7 S | Difference |
|---|---|---|---|
| Mass | 77.6 kg/m | 81.4 kg/m | -4.7% |
| Depth | 450 mm | 457.2 mm | -1.6% |
| Width | 190 mm | 152.4 mm | +24.7% |
| Web thickness | 9.4 mm | 11.7 mm | -19.7% |
| Flange thickness | 14.6 mm | 17.6 mm | -17.0% |
| Area | 98.8 cm² | 103.2 cm² | -4.3% |
| Second moment, major (Iy) | 33,700 cm⁴ | 33,340 cm⁴ | +1.1% |
| Plastic modulus, major (Wpl,y) | 1,700 cm³ | 1,704.3 cm³ | -0.3% |
| Elastic modulus, major (Wel,y) | 1,500 cm³ | 1,458.4 cm³ | +2.9% |
| Second moment, minor (Iz) | 1,680 cm⁴ | 861.6 cm⁴ | +95.0% |
| Plastic modulus, minor (Wpl,z) | 276 cm³ | 198.28 cm³ | +39.2% |
| Radius of gyration, minor (iz) | 4.12 cm | 2.9 cm | +42.1% |
| Torsion constant (It) | 66.7 cm⁴ | 96.98 cm⁴ | -31.2% |
IPE 450 to EN 10365 · Continental Steel; S 18X54.7 to AISC Shapes Database v16.0. Difference is expressed relative to S 18X54.7.
How to choose between them
On stiffness, IPE 450 has the larger second moment of area: 33,700 cm⁴ against 33,340 cm⁴, a difference of 1.1%. 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 450 is the more efficient section: 21.9 against 20.9 cm³ per kg/m, 4.6% 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 450 has 276 cm³ of minor-axis plastic modulus against 198.28 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. IPE sections are specified to EN 10365 · Continental Steel and S 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 4.7% weight.
In short, S 18X54.7 is the stronger section and IPE 450 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.