Tee 191×229×81 vs WT 9X65
Tee 191×229×81 is an Tees (from UB) section from the UK Blue Book (SCI P363); WT 9X65 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 507 cm³ against 499.81 cm³ of plastic modulus, a difference of 1.4%. Tee 191×229×81 is the lighter of the two at 80.7 kg/m against 96.7 kg/m, a saving of 16.5% on steel weight. Both are about 245 mm deep, so either fits the same construction zone.
| Property | Tee 191×229×81 Tees (from UB) | WT 9X65 WT | Difference |
|---|---|---|---|
| Mass | 80.7 kg/m | 96.7 kg/m | -16.5% |
| Depth | 246 mm | 244.6 mm | +0.6% |
| Width | 199.4 mm | 284.5 mm | -29.9% |
| Web thickness | 18 mm | 17 mm | +5.9% |
| Flange thickness | 32 mm | 30.5 mm | +4.9% |
| Area | 103 cm² | 123.9 cm² | -16.9% |
| Second moment, major (Iy) | 5,160 cm⁴ | 5,286 cm⁴ | -2.4% |
| Plastic modulus, major (Wpl,y) | 507 cm³ | 499.81 cm³ | +1.4% |
| Elastic modulus, major (Wel,y) | 281 cm³ | 273.66 cm³ | +2.7% |
| Second moment, minor (Iz) | 2,130 cm⁴ | 5,786 cm⁴ | -63.2% |
| Plastic modulus, minor (Wpl,z) | 336 cm³ | 627.62 cm³ | -46.5% |
| Radius of gyration, minor (iz) | 4.55 cm | 6.86 cm | -33.7% |
| Torsion constant (It) | 256 cm⁴ | 300.9 cm⁴ | -14.9% |
Tee 191×229×81 to BS EN 10365:2017; WT 9X65 to AISC Shapes Database v16.0. Difference is expressed relative to WT 9X65.
How to choose between them
On stiffness, WT 9X65 has the larger second moment of area: 5,286 cm⁴ against 5,160 cm⁴, a difference of 2.4%. 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 191×229×81 is the more efficient section: 6.3 against 5.2 cm³ per kg/m, 21.6% 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.
The two diverge much more about the minor axis: WT 9X65 has 627.62 cm³ of minor-axis plastic modulus against 336 cm³, 46.5% 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 16.5% weight.
In short, Tee 191×229×81 is the stronger section and Tee 191×229×81 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.