UB 254×146×43 vs H-250x175x7x11-44.1
UB 254×146×43 is an UB section from the UK Blue Book (SCI P363); H-250x175x7x11-44.1 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 566 cm³ against 558 cm³ of plastic modulus, a difference of 1.4%. UB 254×146×43 is the lighter of the two at 43 kg/m against 44.1 kg/m, a saving of 2.5% on steel weight. UB 254×146×43 is deeper, 259.6 mm against 244 mm, which matters where the floor zone is tight.
| Property | UB 254×146×43 UB | H-250x175x7x11-44.1 MB & MC | Difference |
|---|---|---|---|
| Mass | 43 kg/m | 44.1 kg/m | -2.5% |
| Depth | 259.6 mm | 244 mm | +6.4% |
| Width | 147.3 mm | 175 mm | -15.8% |
| Web thickness | 7.2 mm | 7 mm | +2.9% |
| Flange thickness | 12.7 mm | 11 mm | +15.5% |
| Area | 54.8 cm² | 56.2 cm² | -2.5% |
| Second moment, major (Iy) | 6,540 cm⁴ | 6,122 cm⁴ | +6.8% |
| Plastic modulus, major (Wpl,y) | 566 cm³ | 558 cm³ | +1.4% |
| Elastic modulus, major (Wel,y) | 504 cm³ | 502 cm³ | +0.4% |
| Second moment, minor (Iz) | 677 cm⁴ | 985 cm⁴ | -31.3% |
| Plastic modulus, minor (Wpl,z) | 141 cm³ | 173 cm³ | -18.5% |
| Radius of gyration, minor (iz) | 3.52 cm | 4.19 cm | -16.0% |
| Torsion constant (It) | 23.9 cm⁴ | 23.2 cm⁴ | +3.0% |
UB 254×146×43 to BS EN 10365:2017; H-250x175x7x11-44.1 to Continental Steel. Difference is expressed relative to H-250x175x7x11-44.1.
How to choose between them
On stiffness, UB 254×146×43 has the larger second moment of area: 6,540 cm⁴ against 6,122 cm⁴, a difference of 6.8%. 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, UB 254×146×43 is the more efficient section: 13.2 against 12.7 cm³ per kg/m, 4.0% 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: H-250x175x7x11-44.1 has 173 cm³ of minor-axis plastic modulus against 141 cm³, 18.5% 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. UB sections are specified to BS EN 10365:2017 and MB & MC to Continental Steel; 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 2.5% weight.
In short, UB 254×146×43 is the stronger section and UB 254×146×43 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.