UC 152×152×30 vs H-150x150x7x10-31.5
UC 152×152×30 is an UC section from the UK Blue Book (SCI P363); H-150x150x7x10-31.5 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 248 cm³ against 246 cm³ of plastic modulus, a difference of 0.8%. UC 152×152×30 is the lighter of the two at 30 kg/m against 31.5 kg/m, a saving of 4.8% on steel weight. UC 152×152×30 is deeper, 157.6 mm against 150 mm, which matters where the floor zone is tight.
| Property | UC 152×152×30 UC | H-150x150x7x10-31.5 MB & MC | Difference |
|---|---|---|---|
| Mass | 30 kg/m | 31.5 kg/m | -4.8% |
| Depth | 157.6 mm | 150 mm | +5.1% |
| Width | 152.9 mm | 150 mm | +1.9% |
| Web thickness | 6.5 mm | 7 mm | -7.1% |
| Flange thickness | 9.4 mm | 10 mm | -6.0% |
| Area | 38.3 cm² | 40.1 cm² | -4.5% |
| Second moment, major (Iy) | 1,750 cm⁴ | 1,641 cm⁴ | +6.6% |
| Plastic modulus, major (Wpl,y) | 248 cm³ | 246 cm³ | +0.8% |
| Elastic modulus, major (Wel,y) | 222 cm³ | 219 cm³ | +1.4% |
| Second moment, minor (Iz) | 560 cm⁴ | 563 cm⁴ | -0.5% |
| Plastic modulus, minor (Wpl,z) | 112 cm³ | 115 cm³ | -2.6% |
| Radius of gyration, minor (iz) | 3.83 cm | 3.75 cm | +2.1% |
| Torsion constant (It) | 10.5 cm⁴ | 13.5 cm⁴ | -22.2% |
UC 152×152×30 to BS EN 10365:2017; H-150x150x7x10-31.5 to Continental Steel. Difference is expressed relative to H-150x150x7x10-31.5.
How to choose between them
On stiffness, UC 152×152×30 has the larger second moment of area: 1,750 cm⁴ against 1,641 cm⁴, a difference of 6.6%. 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, UC 152×152×30 is the more efficient section: 8.3 against 7.8 cm³ per kg/m, 5.9% 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.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. UC 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 4.8% weight.
In short, UC 152×152×30 is the stronger section and UC 152×152×30 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.