Tee 133×102×15 vs WT 4X10.5
Tee 133×102×15 is an Tees (from UB) section from the UK Blue Book (SCI P363); WT 4X10.5 is the closest equivalent in the American AISC Shapes Database. WT 4X10.5 carries more bending: 34.577 cm³ of plastic modulus against 33.5 cm³, 3.1% more. Tee 133×102×15 is the lighter of the two at 15 kg/m against 15.6 kg/m, a saving of 3.8% on steel weight. Both are about 104 mm deep, so either fits the same construction zone.
| Property | Tee 133×102×15 Tees (from UB) | WT 4X10.5 WT | Difference |
|---|---|---|---|
| Mass | 15 kg/m | 15.6 kg/m | -3.8% |
| Depth | 103.3 mm | 105.2 mm | -1.8% |
| Width | 133.9 mm | 133.9 mm | same |
| Web thickness | 6.4 mm | 6.4 mm | same |
| Flange thickness | 9.6 mm | 10.2 mm | -5.9% |
| Area | 19.1 cm² | 19.9 cm² | -4.0% |
| Second moment, major (Iy) | 154 cm⁴ | 162.3 cm⁴ | -5.1% |
| Plastic modulus, major (Wpl,y) | 33.5 cm³ | 34.577 cm³ | -3.1% |
| Elastic modulus, major (Wel,y) | 18.8 cm³ | 19.337 cm³ | -2.8% |
| Second moment, minor (Iz) | 192 cm⁴ | 203.1 cm⁴ | -5.5% |
| Plastic modulus, minor (Wpl,z) | 44.1 cm³ | 46.539 cm³ | -5.2% |
| Radius of gyration, minor (iz) | 3.17 cm | 3.2 cm | -0.9% |
| Torsion constant (It) | 5.13 cm⁴ | 5.87 cm⁴ | -12.6% |
Tee 133×102×15 to BS EN 10365:2017; WT 4X10.5 to AISC Shapes Database v16.0. Difference is expressed relative to WT 4X10.5.
How to choose between them
On stiffness, WT 4X10.5 has the larger second moment of area: 162.3 cm⁴ against 154 cm⁴, a difference of 5.1%. 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 (2.2 against 2.2 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. Tees (from UB) sections are specified to BS EN 10365:2017 and WT 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 3.8% weight.
In short, WT 4X10.5 is the stronger section and Tee 133×102×15 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.