WT 6X48 vs Tee 305×152×69
WT 6X48 is an WT section from the American AISC Shapes Database; Tee 305×152×69 is the closest equivalent in the UK Blue Book (SCI P363). WT 6X48 carries more bending: 195.01 cm³ of plastic modulus against 188 cm³, 3.7% more. Tee 305×152×69 is the lighter of the two at 68.4 kg/m against 71.4 kg/m, a saving of 4.4% on steel weight. Both are about 161 mm deep, so either fits the same construction zone.
| Property | WT 6X48 WT | Tee 305×152×69 Tees (from UC) | Difference |
|---|---|---|---|
| Mass | 71.4 kg/m | 68.4 kg/m | +4.4% |
| Depth | 161.5 mm | 160.2 mm | +0.8% |
| Width | 309.9 mm | 309.2 mm | +0.2% |
| Web thickness | 14 mm | 13.8 mm | +1.4% |
| Flange thickness | 22.9 mm | 21.7 mm | +5.5% |
| Area | 91 cm² | 87.2 cm² | +4.4% |
| Second moment, major (Iy) | 1,332 cm⁴ | 1,290 cm⁴ | +3.3% |
| Plastic modulus, major (Wpl,y) | 195.01 cm³ | 188 cm³ | +3.7% |
| Elastic modulus, major (Wel,y) | 100.29 cm³ | 97.7 cm³ | +2.7% |
| Second moment, minor (Iz) | 5,619 cm⁴ | 5,350 cm⁴ | +5.0% |
| Plastic modulus, minor (Wpl,z) | 552.24 cm³ | 526 cm³ | +5.0% |
| Radius of gyration, minor (iz) | 7.85 cm | 7.83 cm | +0.3% |
| Torsion constant (It) | 142.4 cm⁴ | 124 cm⁴ | +14.8% |
WT 6X48 to AISC Shapes Database v16.0; Tee 305×152×69 to BS EN 10365:2017. Difference is expressed relative to Tee 305×152×69.
How to choose between them
On stiffness, WT 6X48 has the larger second moment of area: 1,332 cm⁴ against 1,290 cm⁴, a difference of 3.3%. 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, the two are equally efficient (2.7 against 2.7 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 4.4% weight.
In short, WT 6X48 is the stronger section and Tee 305×152×69 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.