UB 533×210×101 vs IPE O 500
UB 533×210×101 is an UB section from the UK Blue Book (SCI P363); IPE O 500 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 2610 cm³ against 2610 cm³ of plastic modulus, a difference of 0.0%. UB 533×210×101 is the lighter of the two at 101 kg/m against 107 kg/m, a saving of 5.6% on steel weight. UB 533×210×101 is deeper, 536.7 mm against 506 mm, which matters where the floor zone is tight.
| Property | UB 533×210×101 UB | IPE O 500 IPE | Difference |
|---|---|---|---|
| Mass | 101 kg/m | 107 kg/m | -5.6% |
| Depth | 536.7 mm | 506 mm | +6.1% |
| Width | 210 mm | 202 mm | +4.0% |
| Web thickness | 10.8 mm | 12 mm | -10.0% |
| Flange thickness | 17.4 mm | 19 mm | -8.4% |
| Area | 129 cm² | 137 cm² | -5.8% |
| Second moment, major (Iy) | 61,500 cm⁴ | 57,800 cm⁴ | +6.4% |
| Plastic modulus, major (Wpl,y) | 2,610 cm³ | 2,610 cm³ | same |
| Elastic modulus, major (Wel,y) | 2,290 cm³ | 2,280 cm³ | +0.4% |
| Second moment, minor (Iz) | 2,690 cm⁴ | 2,620 cm⁴ | +2.7% |
| Plastic modulus, minor (Wpl,z) | 399 cm³ | 409 cm³ | -2.4% |
| Radius of gyration, minor (iz) | 4.57 cm | 4.38 cm | +4.3% |
| Torsion constant (It) | 101 cm⁴ | 143 cm⁴ | -29.4% |
UB 533×210×101 to BS EN 10365:2017; IPE O 500 to EN 10365 · Continental Steel. Difference is expressed relative to IPE O 500.
How to choose between them
On stiffness, UB 533×210×101 has the larger second moment of area: 61,500 cm⁴ against 57,800 cm⁴, a difference of 6.4%. 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, UB 533×210×101 is the more efficient section: 25.8 against 24.4 cm³ per kg/m, 5.9% 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. 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 5.6% weight.
In short, IPE O 500 is the stronger section and UB 533×210×101 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.