UB 914×305×253 vs H-900x300x16x28-243
UB 914×305×253 is an UB section from the UK Blue Book (SCI P363); H-900x300x16x28-243 is the closest equivalent in the European (Continental) range. UB 914×305×253 carries more bending: 10900 cm³ of plastic modulus against 10450 cm³, 4.3% more. H-900x300x16x28-243 is the lighter of the two at 243 kg/m against 253.4 kg/m, a saving of 4.3% on steel weight. UB 914×305×253 is deeper, 918.4 mm against 900 mm, which matters where the floor zone is tight.
| Property | UB 914×305×253 UB | H-900x300x16x28-243 MB & MC | Difference |
|---|---|---|---|
| Mass | 253.4 kg/m | 243 kg/m | +4.3% |
| Depth | 918.4 mm | 900 mm | +2.0% |
| Width | 305.5 mm | 300 mm | +1.8% |
| Web thickness | 17.3 mm | 16 mm | +8.1% |
| Flange thickness | 27.9 mm | 28 mm | -0.4% |
| Area | 323 cm² | 310 cm² | +4.2% |
| Second moment, major (Iy) | 436,000 cm⁴ | 411,300 cm⁴ | +6.0% |
| Plastic modulus, major (Wpl,y) | 10,900 cm³ | 10,450 cm³ | +4.3% |
| Elastic modulus, major (Wel,y) | 9,500 cm³ | 9,139 cm³ | +4.0% |
| Second moment, minor (Iz) | 13,300 cm⁴ | 12,650 cm⁴ | +5.1% |
| Plastic modulus, minor (Wpl,z) | 1,370 cm³ | 1,324 cm³ | +3.5% |
| Radius of gyration, minor (iz) | 6.42 cm | 6.39 cm | +0.5% |
| Torsion constant (It) | 626 cm⁴ | 633 cm⁴ | -1.1% |
UB 914×305×253 to BS EN 10365:2017; H-900x300x16x28-243 to Continental Steel. Difference is expressed relative to H-900x300x16x28-243.
How to choose between them
On stiffness, UB 914×305×253 has the larger second moment of area: 436,000 cm⁴ against 411,300 cm⁴, a difference of 6.0%. 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 (43.0 against 43.0 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. 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 4.3% weight.
In short, UB 914×305×253 is the stronger section and H-900x300x16x28-243 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.