UB 203×102×23 vs IPE AA 220
UB 203×102×23 is an UB section from the UK Blue Book (SCI P363); IPE AA 220 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 234 cm³ against 230 cm³ of plastic modulus, a difference of 1.7%. IPE AA 220 is the lighter of the two at 21.2 kg/m against 23.1 kg/m, a saving of 9.0% on steel weight. IPE AA 220 is deeper, 216.4 mm against 203.2 mm, which matters where the floor zone is tight.
| Property | UB 203×102×23 UB | IPE AA 220 IPE | Difference |
|---|---|---|---|
| Mass | 23.1 kg/m | 21.2 kg/m | +9.0% |
| Depth | 203.2 mm | 216.4 mm | -6.1% |
| Width | 101.8 mm | 110 mm | -7.5% |
| Web thickness | 5.4 mm | 4.7 mm | +14.9% |
| Flange thickness | 9.3 mm | 7.4 mm | +25.7% |
| Area | 29.4 cm² | 27 cm² | +8.9% |
| Second moment, major (Iy) | 2,100 cm⁴ | 2,220 cm⁴ | -5.4% |
| Plastic modulus, major (Wpl,y) | 234 cm³ | 230 cm³ | +1.7% |
| Elastic modulus, major (Wel,y) | 207 cm³ | 205 cm³ | +1.0% |
| Second moment, minor (Iz) | 164 cm⁴ | 165 cm⁴ | -0.6% |
| Plastic modulus, minor (Wpl,z) | 49.7 cm³ | 46.5 cm³ | +6.9% |
| Radius of gyration, minor (iz) | 2.36 cm | 2.47 cm | -4.5% |
| Torsion constant (It) | 7.02 cm⁴ | 5.06 cm⁴ | +38.7% |
UB 203×102×23 to BS EN 10365:2017; IPE AA 220 to EN 10365 · Continental Steel. Difference is expressed relative to IPE AA 220.
How to choose between them
On stiffness, IPE AA 220 has the larger second moment of area: 2,220 cm⁴ against 2,100 cm⁴, a difference of 5.4%. 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, IPE AA 220 is the more efficient section: 10.8 against 10.1 cm³ per kg/m, 6.6% 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. UB sections are specified to BS EN 10365:2017 and IPE 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 9.0% weight.
In short, UB 203×102×23 is the stronger section and IPE AA 220 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.