UC 356×406×340 vs W 14X233
UC 356×406×340 is an UC section from the UK Blue Book (SCI P363); W 14X233 is the closest equivalent in the American AISC Shapes Database. W 14X233 carries more bending: 7144.8 cm³ of plastic modulus against 7000 cm³, 2.0% more. They weigh essentially the same, 339.9 kg/m and 346.7 kg/m. Both are about 406 mm deep, so either fits the same construction zone.
| Property | UC 356×406×340 UC | W 14X233 W | Difference |
|---|---|---|---|
| Mass | 339.9 kg/m | 346.7 kg/m | -2.0% |
| Depth | 406.4 mm | 406.4 mm | same |
| Width | 403 mm | 403.9 mm | -0.2% |
| Web thickness | 26.6 mm | 27.2 mm | -2.2% |
| Flange thickness | 42.9 mm | 43.7 mm | -1.8% |
| Area | 433 cm² | 441.9 cm² | -2.0% |
| Second moment, major (Iy) | 123,000 cm⁴ | 125,286 cm⁴ | -1.8% |
| Plastic modulus, major (Wpl,y) | 7,000 cm³ | 7,144.8 cm³ | -2.0% |
| Elastic modulus, major (Wel,y) | 6,030 cm³ | 6,145.1 cm³ | -1.9% |
| Second moment, minor (Iz) | 46,900 cm⁴ | 47,867 cm⁴ | -2.0% |
| Plastic modulus, minor (Wpl,z) | 3,540 cm³ | 3,621.5 cm³ | -2.3% |
| Radius of gyration, minor (iz) | 10.4 cm | 10.41 cm | -0.1% |
| Torsion constant (It) | 2,340 cm⁴ | 2,477 cm⁴ | -5.5% |
UC 356×406×340 to BS EN 10365:2017; W 14X233 to AISC Shapes Database v16.0. Difference is expressed relative to W 14X233.
How to choose between them
On stiffness, W 14X233 has the larger second moment of area: 125,286 cm⁴ against 123,000 cm⁴, a difference of 1.8%. 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 (20.6 against 20.6 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. UC 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, W 14X233 is the stronger section and UC 356×406×340 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.