Tee 165×267×43 vs WT 10.5X31
Tee 165×267×43 is an Tees (from UB) section from the UK Blue Book (SCI P363); WT 10.5X31 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 346 cm³ against 345.77 cm³ of plastic modulus, a difference of 0.1%. Tee 165×267×43 is the lighter of the two at 42.3 kg/m against 46.1 kg/m, a saving of 8.2% on steel weight. Both are about 267 mm deep, so either fits the same construction zone.
| Property | Tee 165×267×43 Tees (from UB) | WT 10.5X31 WT | Difference |
|---|---|---|---|
| Mass | 42.3 kg/m | 46.1 kg/m | -8.2% |
| Depth | 267.1 mm | 266.7 mm | +0.1% |
| Width | 166.5 mm | 209.3 mm | -20.4% |
| Web thickness | 10.3 mm | 10.2 mm | +1.0% |
| Flange thickness | 16.5 mm | 15.6 mm | +5.8% |
| Area | 54 cm² | 58.9 cm² | -8.3% |
| Second moment, major (Iy) | 3,750 cm⁴ | 3,904 cm⁴ | -3.9% |
| Plastic modulus, major (Wpl,y) | 346 cm³ | 345.77 cm³ | +0.1% |
| Elastic modulus, major (Wel,y) | 192 cm³ | 195.01 cm³ | -1.5% |
| Second moment, minor (Iz) | 637 cm⁴ | 1,195 cm⁴ | -46.7% |
| Plastic modulus, minor (Wpl,z) | 122 cm³ | 178.62 cm³ | -31.7% |
| Radius of gyration, minor (iz) | 3.44 cm | 4.5 cm | -23.6% |
| Torsion constant (It) | 36.8 cm⁴ | 38 cm⁴ | -3.2% |
Tee 165×267×43 to BS EN 10365:2017; WT 10.5X31 to AISC Shapes Database v16.0. Difference is expressed relative to WT 10.5X31.
How to choose between them
On stiffness, WT 10.5X31 has the larger second moment of area: 3,904 cm⁴ against 3,750 cm⁴, a difference of 3.9%. 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, Tee 165×267×43 is the more efficient section: 8.2 against 7.5 cm³ per kg/m, 9.1% 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.
The two diverge much more about the minor axis: WT 10.5X31 has 178.62 cm³ of minor-axis plastic modulus against 122 cm³, 31.7% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
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 8.2% weight.
In short, Tee 165×267×43 is the stronger section and Tee 165×267×43 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.