UB 533×210×138 vs HE 600 AA
UB 533×210×138 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: 3610 cm³ against 3620 cm³ of plastic modulus, a difference of 0.3%. HE 600 AA is the lighter of the two at 129 kg/m against 138.3 kg/m, a saving of 7.2% on steel weight. HE 600 AA is deeper, 571 mm against 549.1 mm, which matters where the floor zone is tight.
| Property | UB 533×210×138 UB | HE 600 AA HE | Difference |
|---|---|---|---|
| Mass | 138.3 kg/m | 129 kg/m | +7.2% |
| Depth | 549.1 mm | 571 mm | -3.8% |
| Width | 213.9 mm | 300 mm | -28.7% |
| Web thickness | 14.7 mm | 12 mm | +22.5% |
| Flange thickness | 23.6 mm | 15.5 mm | +52.3% |
| Area | 176 cm² | 164 cm² | +7.3% |
| Second moment, major (Iy) | 86,100 cm⁴ | 91,900 cm⁴ | -6.3% |
| Plastic modulus, major (Wpl,y) | 3,610 cm³ | 3,620 cm³ | -0.3% |
| Elastic modulus, major (Wel,y) | 3,140 cm³ | 3,220 cm³ | -2.5% |
| Second moment, minor (Iz) | 3,860 cm⁴ | 6,990 cm⁴ | -44.8% |
| Plastic modulus, minor (Wpl,z) | 568 cm³ | 724 cm³ | -21.5% |
| Radius of gyration, minor (iz) | 4.68 cm | 6.53 cm | -28.3% |
| Torsion constant (It) | 250 cm⁴ | 142 cm⁴ | +76.1% |
UB 533×210×138 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, HE 600 AA has the larger second moment of area: 91,900 cm⁴ against 86,100 cm⁴, a difference of 6.3%. 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, HE 600 AA is the more efficient section: 28.1 against 26.1 cm³ per kg/m, 7.0% 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: HE 600 AA has 724 cm³ of minor-axis plastic modulus against 568 cm³, 21.5% 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 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 7.2% weight.
In short, HE 600 AA is the stronger section and HE 600 AA 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.