WT 9X23 vs Tee 191×229×37
WT 9X23 is an WT section from the American AISC Shapes Database; Tee 191×229×37 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 227.78 cm³ against 225 cm³ of plastic modulus, a difference of 1.2%. WT 9X23 is the lighter of the two at 34.2 kg/m against 37.1 kg/m, a saving of 7.8% on steel weight. Both are about 229 mm deep, so either fits the same construction zone.
| Property | WT 9X23 WT | Tee 191×229×37 Tees (from UB) | Difference |
|---|---|---|---|
| Mass | 34.2 kg/m | 37.1 kg/m | -7.8% |
| Depth | 229.4 mm | 228.4 mm | +0.4% |
| Width | 153.9 mm | 190.4 mm | -19.2% |
| Web thickness | 9.1 mm | 9 mm | +1.1% |
| Flange thickness | 15.4 mm | 14.5 mm | +6.2% |
| Area | 43.7 cm² | 47.3 cm² | -7.6% |
| Second moment, major (Iy) | 2,169 cm⁴ | 2,220 cm⁴ | -2.3% |
| Plastic modulus, major (Wpl,y) | 227.78 cm³ | 225 cm³ | +1.2% |
| Elastic modulus, major (Wel,y) | 127.33 cm³ | 127 cm³ | +0.3% |
| Second moment, minor (Iz) | 470.3 cm⁴ | 836 cm⁴ | -43.7% |
| Plastic modulus, minor (Wpl,z) | 95.7 cm³ | 136 cm³ | -29.6% |
| Radius of gyration, minor (iz) | 3.28 cm | 4.2 cm | -21.9% |
| Torsion constant (It) | 25.35 cm⁴ | 25.8 cm⁴ | -1.7% |
WT 9X23 to AISC Shapes Database v16.0; Tee 191×229×37 to BS EN 10365:2017. Difference is expressed relative to Tee 191×229×37.
How to choose between them
On stiffness, Tee 191×229×37 has the larger second moment of area: 2,220 cm⁴ against 2,169 cm⁴, a difference of 2.3%. 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 9X23 is the more efficient section: 6.7 against 6.1 cm³ per kg/m, 9.8% 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 191×229×37 has 136 cm³ of minor-axis plastic modulus against 95.7 cm³, 29.6% 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 7.8% weight.
In short, WT 9X23 is the stronger section and WT 9X23 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.