IPE 360 vs UB 356×171×57
IPE 360 is an IPE section from the European (Continental) range; UB 356×171×57 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 1020 cm³ against 1010 cm³ of plastic modulus, a difference of 1.0%. They weigh essentially the same, 57.1 kg/m and 57 kg/m. Both are about 359 mm deep, so either fits the same construction zone.
| Property | IPE 360 IPE | UB 356×171×57 UB | Difference |
|---|---|---|---|
| Mass | 57.1 kg/m | 57 kg/m | +0.2% |
| Depth | 360 mm | 358 mm | +0.6% |
| Width | 170 mm | 172.2 mm | -1.3% |
| Web thickness | 8 mm | 8.1 mm | -1.2% |
| Flange thickness | 12.7 mm | 13 mm | -2.3% |
| Area | 72.7 cm² | 72.6 cm² | +0.1% |
| Second moment, major (Iy) | 16,300 cm⁴ | 16,000 cm⁴ | +1.9% |
| Plastic modulus, major (Wpl,y) | 1,020 cm³ | 1,010 cm³ | +1.0% |
| Elastic modulus, major (Wel,y) | 904 cm³ | 896 cm³ | +0.9% |
| Second moment, minor (Iz) | 1,040 cm⁴ | 1,110 cm⁴ | -6.3% |
| Plastic modulus, minor (Wpl,z) | 191 cm³ | 199 cm³ | -4.0% |
| Radius of gyration, minor (iz) | 3.79 cm | 3.91 cm | -3.1% |
| Torsion constant (It) | 37.4 cm⁴ | 33.4 cm⁴ | +12.0% |
IPE 360 to EN 10365 · Continental Steel; UB 356×171×57 to BS EN 10365:2017. Difference is expressed relative to UB 356×171×57.
How to choose between them
On stiffness, IPE 360 has the larger second moment of area: 16,300 cm⁴ against 16,000 cm⁴, a difference of 1.9%. 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 (17.9 against 17.7 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 UB to BS EN 10365:2017; 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.