UB 305×127×48 vs IPE A 330
UB 305×127×48 is an UB section from the UK Blue Book (SCI P363); IPE A 330 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 711 cm³ against 702 cm³ of plastic modulus, a difference of 1.3%. IPE A 330 is the lighter of the two at 43 kg/m against 48.1 kg/m, a saving of 11.9% on steel weight. IPE A 330 is deeper, 327 mm against 311 mm, which matters where the floor zone is tight.
| Property | UB 305×127×48 UB | IPE A 330 IPE | Difference |
|---|---|---|---|
| Mass | 48.1 kg/m | 43 kg/m | +11.9% |
| Depth | 311 mm | 327 mm | -4.9% |
| Width | 125.3 mm | 160 mm | -21.7% |
| Web thickness | 9 mm | 6.5 mm | +38.5% |
| Flange thickness | 14 mm | 10 mm | +40.0% |
| Area | 61.3 cm² | 54.7 cm² | +12.1% |
| Second moment, major (Iy) | 9,570 cm⁴ | 10,200 cm⁴ | -6.2% |
| Plastic modulus, major (Wpl,y) | 711 cm³ | 702 cm³ | +1.3% |
| Elastic modulus, major (Wel,y) | 616 cm³ | 626 cm³ | -1.6% |
| Second moment, minor (Iz) | 461 cm⁴ | 685 cm⁴ | -32.7% |
| Plastic modulus, minor (Wpl,z) | 116 cm³ | 133 cm³ | -12.8% |
| Radius of gyration, minor (iz) | 2.74 cm | 3.54 cm | -22.6% |
| Torsion constant (It) | 31.8 cm⁴ | 19.6 cm⁴ | +62.2% |
UB 305×127×48 to BS EN 10365:2017; IPE A 330 to EN 10365 · Continental Steel. Difference is expressed relative to IPE A 330.
How to choose between them
On stiffness, IPE A 330 has the larger second moment of area: 10,200 cm⁴ against 9,570 cm⁴, a difference of 6.2%. 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 A 330 is the more efficient section: 16.3 against 14.8 cm³ per kg/m, 9.5% 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: IPE A 330 has 133 cm³ of minor-axis plastic modulus against 116 cm³, 12.8% 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 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 11.9% weight.
In short, UB 305×127×48 is the stronger section and IPE A 330 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.