W 12X152 vs UC 356×368×202
W 12X152 is an W section from the American AISC Shapes Database; UC 356×368×202 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 3982.1 cm³ against 3970 cm³ of plastic modulus, a difference of 0.3%. UC 356×368×202 is the lighter of the two at 201.9 kg/m against 226.2 kg/m, a saving of 12.0% on steel weight. UC 356×368×202 is deeper, 374.6 mm against 348 mm, which matters where the floor zone is tight.
| Property | W 12X152 W | UC 356×368×202 UC | Difference |
|---|---|---|---|
| Mass | 226.2 kg/m | 201.9 kg/m | +12.0% |
| Depth | 348 mm | 374.6 mm | -7.1% |
| Width | 317.5 mm | 374.7 mm | -15.3% |
| Web thickness | 22.1 mm | 16.5 mm | +33.9% |
| Flange thickness | 35.6 mm | 27 mm | +31.9% |
| Area | 288.4 cm² | 257 cm² | +12.2% |
| Second moment, major (Iy) | 59,521 cm⁴ | 66,300 cm⁴ | -10.2% |
| Plastic modulus, major (Wpl,y) | 3,982.1 cm³ | 3,970 cm³ | +0.3% |
| Elastic modulus, major (Wel,y) | 3,424.9 cm³ | 3,540 cm³ | -3.3% |
| Second moment, minor (Iz) | 18,897 cm⁴ | 23,700 cm⁴ | -20.3% |
| Plastic modulus, minor (Wpl,z) | 1,819 cm³ | 1,920 cm³ | -5.3% |
| Radius of gyration, minor (iz) | 8.1 cm | 9.6 cm | -15.6% |
| Torsion constant (It) | 1,074 cm⁴ | 558 cm⁴ | +92.5% |
W 12X152 to AISC Shapes Database v16.0; UC 356×368×202 to BS EN 10365:2017. Difference is expressed relative to UC 356×368×202.
How to choose between them
On stiffness, UC 356×368×202 has the larger second moment of area: 66,300 cm⁴ against 59,521 cm⁴, a difference of 10.2%. 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 of steel, UC 356×368×202 is the more efficient section: 19.7 against 17.6 cm³ per kg/m, 10.5% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. W sections are specified to AISC Shapes Database v16.0 and UC 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 12.0% weight.
In short, W 12X152 is the stronger section and UC 356×368×202 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.