UB 914×419×388 vs W 36X262
UB 914×419×388 is an UB section from the UK Blue Book (SCI P363); W 36X262 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 17700 cm³ against 18025.8 cm³ of plastic modulus, a difference of 1.8%. They weigh essentially the same, 388 kg/m and 389.9 kg/m. Both are about 929 mm deep, so either fits the same construction zone.
| Property | UB 914×419×388 UB | W 36X262 W | Difference |
|---|---|---|---|
| Mass | 388 kg/m | 389.9 kg/m | -0.5% |
| Depth | 921 mm | 937.3 mm | -1.7% |
| Width | 420.5 mm | 421.6 mm | -0.3% |
| Web thickness | 21.4 mm | 21.3 mm | +0.5% |
| Flange thickness | 36.6 mm | 36.6 mm | same |
| Area | 494 cm² | 498.1 cm² | -0.8% |
| Second moment, major (Iy) | 720,000 cm⁴ | 745,054 cm⁴ | -3.4% |
| Plastic modulus, major (Wpl,y) | 17,700 cm³ | 18,025.8 cm³ | -1.8% |
| Elastic modulus, major (Wel,y) | 15,600 cm³ | 15,928.2 cm³ | -2.1% |
| Second moment, minor (Iz) | 45,400 cm⁴ | 45,369 cm⁴ | +0.1% |
| Plastic modulus, minor (Wpl,z) | 3,340 cm³ | 3,343 cm³ | -0.1% |
| Radius of gyration, minor (iz) | 9.59 cm | 9.55 cm | +0.4% |
| Torsion constant (It) | 1,730 cm⁴ | 1,732 cm⁴ | -0.1% |
UB 914×419×388 to BS EN 10365:2017; W 36X262 to AISC Shapes Database v16.0. Difference is expressed relative to W 36X262.
How to choose between them
On stiffness, W 36X262 has the larger second moment of area: 745,054 cm⁴ against 720,000 cm⁴, a difference of 3.4%. 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, the two are equally efficient (45.6 against 46.2 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 W to AISC Shapes Database v16.0; 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.