UB 457×191×89 vs IPE O 450
UB 457×191×89 is an UB section from the UK Blue Book (SCI P363); IPE O 450 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 2010 cm³ against 2050 cm³ of plastic modulus, a difference of 2.0%. UB 457×191×89 is the lighter of the two at 89.3 kg/m against 92.4 kg/m, a saving of 3.4% on steel weight. Both are about 460 mm deep, so either fits the same construction zone.
| Property | UB 457×191×89 UB | IPE O 450 IPE | Difference |
|---|---|---|---|
| Mass | 89.3 kg/m | 92.4 kg/m | -3.4% |
| Depth | 463.4 mm | 456 mm | +1.6% |
| Width | 191.9 mm | 192 mm | -0.1% |
| Web thickness | 10.5 mm | 11 mm | -4.5% |
| Flange thickness | 17.7 mm | 17.6 mm | +0.6% |
| Area | 114 cm² | 118 cm² | -3.4% |
| Second moment, major (Iy) | 41,000 cm⁴ | 40,900 cm⁴ | +0.2% |
| Plastic modulus, major (Wpl,y) | 2,010 cm³ | 2,050 cm³ | -2.0% |
| Elastic modulus, major (Wel,y) | 1,770 cm³ | 1,800 cm³ | -1.7% |
| Second moment, minor (Iz) | 2,090 cm⁴ | 2,080 cm⁴ | +0.5% |
| Plastic modulus, minor (Wpl,z) | 338 cm³ | 341 cm³ | -0.9% |
| Radius of gyration, minor (iz) | 4.29 cm | 4.21 cm | +1.9% |
| Torsion constant (It) | 90.7 cm⁴ | 109 cm⁴ | -16.8% |
UB 457×191×89 to BS EN 10365:2017; IPE O 450 to EN 10365 · Continental Steel. Difference is expressed relative to IPE O 450.
How to choose between them
On stiffness, UB 457×191×89 has the larger second moment of area: 41,000 cm⁴ against 40,900 cm⁴, a difference of 0.2%. 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 (22.5 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. UB sections are specified to BS EN 10365:2017 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 3.4% weight.
In short, IPE O 450 is the stronger section and UB 457×191×89 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.