UB 762×267×173 vs HE 800 AA
UB 762×267×173 is an UB section from the UK Blue Book (SCI P363); HE 800 AA is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 6200 cm³ against 6220 cm³ of plastic modulus, a difference of 0.3%. They weigh essentially the same, 173 kg/m and 172 kg/m. Both are about 766 mm deep, so either fits the same construction zone.
| Property | UB 762×267×173 UB | HE 800 AA HE | Difference |
|---|---|---|---|
| Mass | 173 kg/m | 172 kg/m | +0.6% |
| Depth | 762.2 mm | 770 mm | -1.0% |
| Width | 266.7 mm | 300 mm | -11.1% |
| Web thickness | 14.3 mm | 14 mm | +2.1% |
| Flange thickness | 21.6 mm | 18 mm | +20.0% |
| Area | 220 cm² | 218 cm² | +0.9% |
| Second moment, major (Iy) | 205,000 cm⁴ | 209,000 cm⁴ | -1.9% |
| Plastic modulus, major (Wpl,y) | 6,200 cm³ | 6,220 cm³ | -0.3% |
| Elastic modulus, major (Wel,y) | 5,390 cm³ | 5,430 cm³ | -0.7% |
| Second moment, minor (Iz) | 6,850 cm⁴ | 8,130 cm⁴ | -15.7% |
| Plastic modulus, minor (Wpl,z) | 807 cm³ | 857 cm³ | -5.8% |
| Radius of gyration, minor (iz) | 5.58 cm | 6.1 cm | -8.5% |
| Torsion constant (It) | 267 cm⁴ | 243 cm⁴ | +9.9% |
UB 762×267×173 to BS EN 10365:2017; HE 800 AA to EN 10365 · Continental Steel. Difference is expressed relative to HE 800 AA.
How to choose between them
On stiffness, HE 800 AA has the larger second moment of area: 209,000 cm⁴ against 205,000 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 (35.8 against 36.2 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 HE 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.