WT 10.5X41.5 vs Tee 312×267×75
WT 10.5X41.5 is an WT section from the American AISC Shapes Database; Tee 312×267×75 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 458.84 cm³ against 458 cm³ of plastic modulus, a difference of 0.2%. WT 10.5X41.5 is the lighter of the two at 61.8 kg/m against 75.3 kg/m, a saving of 17.9% on steel weight. Both are about 272 mm deep, so either fits the same construction zone.
| Property | WT 10.5X41.5 WT | Tee 312×267×75 Tees (from UB) | Difference |
|---|---|---|---|
| Mass | 61.8 kg/m | 75.3 kg/m | -17.9% |
| Depth | 271.8 mm | 271.5 mm | +0.1% |
| Width | 212.3 mm | 312 mm | -32.0% |
| Web thickness | 13.1 mm | 12.7 mm | +3.1% |
| Flange thickness | 21.2 mm | 20.3 mm | +4.4% |
| Area | 78.7 cm² | 95.9 cm² | -17.9% |
| Second moment, major (Iy) | 5,286 cm⁴ | 5,620 cm⁴ | -5.9% |
| Plastic modulus, major (Wpl,y) | 458.84 cm³ | 458 cm³ | +0.2% |
| Elastic modulus, major (Wel,y) | 257.28 cm³ | 260 cm³ | -1.0% |
| Second moment, minor (Iz) | 1,694 cm⁴ | 5,140 cm⁴ | -67.0% |
| Plastic modulus, minor (Wpl,z) | 249.08 cm³ | 505 cm³ | -50.7% |
| Radius of gyration, minor (iz) | 4.65 cm | 7.32 cm | -36.5% |
| Torsion constant (It) | 89.91 cm⁴ | 108 cm⁴ | -16.8% |
WT 10.5X41.5 to AISC Shapes Database v16.0; Tee 312×267×75 to BS EN 10365:2017. Difference is expressed relative to Tee 312×267×75.
How to choose between them
On stiffness, Tee 312×267×75 has the larger second moment of area: 5,620 cm⁴ against 5,286 cm⁴, a difference of 5.9%. 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, WT 10.5X41.5 is the more efficient section: 7.4 against 6.1 cm³ per kg/m, 22.1% 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: Tee 312×267×75 has 505 cm³ of minor-axis plastic modulus against 249.08 cm³, 50.7% 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. WT sections are specified to AISC Shapes Database v16.0 and Tees (from UB) 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 17.9% weight.
In short, WT 10.5X41.5 is the stronger section and WT 10.5X41.5 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.