UB 356×171×67 vs IPE O 360
UB 356×171×67 is an UB section from the UK Blue Book (SCI P363); IPE O 360 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 1210 cm³ against 1190 cm³ of plastic modulus, a difference of 1.7%. They weigh essentially the same, 67.1 kg/m and 66 kg/m. Both are about 364 mm deep, so either fits the same construction zone.
| Property | UB 356×171×67 UB | IPE O 360 IPE | Difference |
|---|---|---|---|
| Mass | 67.1 kg/m | 66 kg/m | +1.7% |
| Depth | 363.4 mm | 364 mm | -0.2% |
| Width | 173.2 mm | 172 mm | +0.7% |
| Web thickness | 9.1 mm | 9.2 mm | -1.1% |
| Flange thickness | 15.7 mm | 14.7 mm | +6.8% |
| Area | 85.5 cm² | 84.1 cm² | +1.7% |
| Second moment, major (Iy) | 19,500 cm⁴ | 19,000 cm⁴ | +2.6% |
| Plastic modulus, major (Wpl,y) | 1,210 cm³ | 1,190 cm³ | +1.7% |
| Elastic modulus, major (Wel,y) | 1,070 cm³ | 1,050 cm³ | +1.9% |
| Second moment, minor (Iz) | 1,360 cm⁴ | 1,250 cm⁴ | +8.8% |
| Plastic modulus, minor (Wpl,z) | 243 cm³ | 227 cm³ | +7.0% |
| Radius of gyration, minor (iz) | 3.99 cm | 3.86 cm | +3.4% |
| Torsion constant (It) | 55.7 cm⁴ | 55.7 cm⁴ | same |
UB 356×171×67 to BS EN 10365:2017; IPE O 360 to EN 10365 · Continental Steel. Difference is expressed relative to IPE O 360.
How to choose between them
On stiffness, UB 356×171×67 has the larger second moment of area: 19,500 cm⁴ against 19,000 cm⁴, a difference of 2.6%. 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, the two are equally efficient (18.0 against 18.0 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 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.