UB 914×305×201 vs H-900x300x15x23-210
UB 914×305×201 is an UB section from the UK Blue Book (SCI P363); H-900x300x15x23-210 is the closest equivalent in the European (Continental) range. H-900x300x15x23-210 carries more bending: 8750 cm³ of plastic modulus against 8350 cm³, 4.6% more. UB 914×305×201 is the lighter of the two at 200.9 kg/m against 210 kg/m, a saving of 4.3% on steel weight. Both are about 897 mm deep, so either fits the same construction zone.
| Property | UB 914×305×201 UB | H-900x300x15x23-210 MB & MC | Difference |
|---|---|---|---|
| Mass | 200.9 kg/m | 210 kg/m | -4.3% |
| Depth | 903 mm | 890 mm | +1.5% |
| Width | 303.3 mm | 299 mm | +1.4% |
| Web thickness | 15.1 mm | 15 mm | +0.7% |
| Flange thickness | 20.2 mm | 23 mm | -12.2% |
| Area | 256 cm² | 267 cm² | -4.1% |
| Second moment, major (Iy) | 325,000 cm⁴ | 338,500 cm⁴ | -4.0% |
| Plastic modulus, major (Wpl,y) | 8,350 cm³ | 8,750 cm³ | -4.6% |
| Elastic modulus, major (Wel,y) | 7,200 cm³ | 7,608 cm³ | -5.4% |
| Second moment, minor (Iz) | 9,420 cm⁴ | 10,280 cm⁴ | -8.4% |
| Plastic modulus, minor (Wpl,z) | 982 cm³ | 1,079 cm³ | -9.0% |
| Radius of gyration, minor (iz) | 6.07 cm | 6.2 cm | -2.1% |
| Torsion constant (It) | 291 cm⁴ | 361 cm⁴ | -19.4% |
UB 914×305×201 to BS EN 10365:2017; H-900x300x15x23-210 to Continental Steel. Difference is expressed relative to H-900x300x15x23-210.
How to choose between them
On stiffness, H-900x300x15x23-210 has the larger second moment of area: 338,500 cm⁴ against 325,000 cm⁴, a difference of 4.0%. 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 (41.6 against 41.7 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.
The two diverge much more about the minor axis: H-900x300x15x23-210 has 1079 cm³ of minor-axis plastic modulus against 982 cm³, 9.0% 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 4.3% weight.
In short, H-900x300x15x23-210 is the stronger section and UB 914×305×201 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.