WT 4X24 vs Tee 203×102×36
WT 4X24 is an WT section from the American AISC Shapes Database; Tee 203×102×36 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 64.565 cm³ against 63.6 cm³ of plastic modulus, a difference of 1.5%. They weigh essentially the same, 35.7 kg/m and 35.5 kg/m. Both are about 108 mm deep, so either fits the same construction zone.
| Property | WT 4X24 WT | Tee 203×102×36 Tees (from UC) | Difference |
|---|---|---|---|
| Mass | 35.7 kg/m | 35.5 kg/m | +0.6% |
| Depth | 108 mm | 107.8 mm | +0.2% |
| Width | 206 mm | 206.4 mm | -0.2% |
| Web thickness | 10.2 mm | 10 mm | +2.0% |
| Flange thickness | 17.4 mm | 17.3 mm | +0.6% |
| Area | 45.5 cm² | 45.2 cm² | +0.7% |
| Second moment, major (Iy) | 285.1 cm⁴ | 280 cm⁴ | +1.8% |
| Plastic modulus, major (Wpl,y) | 64.565 cm³ | 63.6 cm³ | +1.5% |
| Elastic modulus, major (Wel,y) | 32.283 cm³ | 31.8 cm³ | +1.5% |
| Second moment, minor (Iz) | 1,270 cm⁴ | 1,270 cm⁴ | same |
| Plastic modulus, minor (Wpl,z) | 186.81 cm³ | 187 cm³ | -0.1% |
| Radius of gyration, minor (iz) | 5.28 cm | 5.3 cm | -0.4% |
| Torsion constant (It) | 40.67 cm⁴ | 40 cm⁴ | +1.7% |
WT 4X24 to AISC Shapes Database v16.0; Tee 203×102×36 to BS EN 10365:2017. Difference is expressed relative to Tee 203×102×36.
How to choose between them
On stiffness, WT 4X24 has the larger second moment of area: 285.1 cm⁴ against 280 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 (1.8 against 1.8 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. WT sections are specified to AISC Shapes Database v16.0 and Tees (from 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 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.