UB 610×229×125 vs HE 600 AA
UB 610×229×125 is an UB section from the UK Blue Book (SCI P363); HE 600 AA is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 3680 cm³ against 3620 cm³ of plastic modulus, a difference of 1.7%. UB 610×229×125 is the lighter of the two at 125.1 kg/m against 129 kg/m, a saving of 3.0% on steel weight. UB 610×229×125 is deeper, 612.2 mm against 571 mm, which matters where the floor zone is tight.
| Property | UB 610×229×125 UB | HE 600 AA HE | Difference |
|---|---|---|---|
| Mass | 125.1 kg/m | 129 kg/m | -3.0% |
| Depth | 612.2 mm | 571 mm | +7.2% |
| Width | 229 mm | 300 mm | -23.7% |
| Web thickness | 11.9 mm | 12 mm | -0.8% |
| Flange thickness | 19.6 mm | 15.5 mm | +26.5% |
| Area | 159 cm² | 164 cm² | -3.0% |
| Second moment, major (Iy) | 98,600 cm⁴ | 91,900 cm⁴ | +7.3% |
| Plastic modulus, major (Wpl,y) | 3,680 cm³ | 3,620 cm³ | +1.7% |
| Elastic modulus, major (Wel,y) | 3,220 cm³ | 3,220 cm³ | same |
| Second moment, minor (Iz) | 3,930 cm⁴ | 6,990 cm⁴ | -43.8% |
| Plastic modulus, minor (Wpl,z) | 535 cm³ | 724 cm³ | -26.1% |
| Radius of gyration, minor (iz) | 4.97 cm | 6.53 cm | -23.9% |
| Torsion constant (It) | 154 cm⁴ | 142 cm⁴ | +8.5% |
UB 610×229×125 to BS EN 10365:2017; HE 600 AA to EN 10365 · Continental Steel. Difference is expressed relative to HE 600 AA.
How to choose between them
On stiffness, UB 610×229×125 has the larger second moment of area: 98,600 cm⁴ against 91,900 cm⁴, a difference of 7.3%. 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, UB 610×229×125 is the more efficient section: 29.4 against 28.1 cm³ per kg/m, 4.8% 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: HE 600 AA has 724 cm³ of minor-axis plastic modulus against 535 cm³, 26.1% 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 HE to EN 10365 · 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 3.0% weight.
In short, UB 610×229×125 is the stronger section and UB 610×229×125 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.