WT 3X7.5 vs Tee 152×76×12
WT 3X7.5 is an WT section from the American AISC Shapes Database; Tee 152×76×12 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 16.879 cm³ against 16.9 cm³ of plastic modulus, a difference of 0.1%. WT 3X7.5 is the lighter of the two at 11.2 kg/m against 11.5 kg/m, a saving of 2.6% on steel weight. Both are about 76 mm deep, so either fits the same construction zone.
| Property | WT 3X7.5 WT | Tee 152×76×12 Tees (from UC) | Difference |
|---|---|---|---|
| Mass | 11.2 kg/m | 11.5 kg/m | -2.6% |
| Depth | 76.2 mm | 76.1 mm | +0.1% |
| Width | 152.1 mm | 152.2 mm | -0.1% |
| Web thickness | 5.8 mm | 5.8 mm | same |
| Flange thickness | 6.6 mm | 6.8 mm | -2.9% |
| Area | 14.3 cm² | 14.6 cm² | -2.1% |
| Second moment, major (Iy) | 58.69 cm⁴ | 58.5 cm⁴ | +0.3% |
| Plastic modulus, major (Wpl,y) | 16.879 cm³ | 16.9 cm³ | -0.1% |
| Elastic modulus, major (Wel,y) | 9.455 cm³ | 9.41 cm³ | +0.5% |
| Second moment, minor (Iz) | 194 cm⁴ | 200 cm⁴ | -3.0% |
| Plastic modulus, minor (Wpl,z) | 38.837 cm³ | 40.1 cm³ | -3.1% |
| Radius of gyration, minor (iz) | 3.68 cm | 3.7 cm | -0.5% |
| Torsion constant (It) | 2.1 cm⁴ | 2.3 cm⁴ | -8.7% |
WT 3X7.5 to AISC Shapes Database v16.0; Tee 152×76×12 to BS EN 10365:2017. Difference is expressed relative to Tee 152×76×12.
How to choose between them
On stiffness, WT 3X7.5 has the larger second moment of area: 58.69 cm⁴ against 58.5 cm⁴, a difference of 0.3%. 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 3X7.5 is the more efficient section: 1.5 against 1.5 cm³ per kg/m, 2.6% 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. 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 2.6% weight.
In short, Tee 152×76×12 is the stronger section and WT 3X7.5 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.