UB 457×191×161 vs HE 500 A
UB 457×191×161 is an UB section from the UK Blue Book (SCI P363); HE 500 A is the closest equivalent in the European (Continental) range. HE 500 A carries more bending: 3950 cm³ of plastic modulus against 3780 cm³, 4.3% more. HE 500 A is the lighter of the two at 155 kg/m against 161.4 kg/m, a saving of 4.1% on steel weight. Both are about 491 mm deep, so either fits the same construction zone.
| Property | UB 457×191×161 UB | HE 500 A HE | Difference |
|---|---|---|---|
| Mass | 161.4 kg/m | 155 kg/m | +4.1% |
| Depth | 492 mm | 490 mm | +0.4% |
| Width | 199.4 mm | 300 mm | -33.5% |
| Web thickness | 18 mm | 12 mm | +50.0% |
| Flange thickness | 32 mm | 23 mm | +39.1% |
| Area | 206 cm² | 198 cm² | +4.0% |
| Second moment, major (Iy) | 79,800 cm⁴ | 87,000 cm⁴ | -8.3% |
| Plastic modulus, major (Wpl,y) | 3,780 cm³ | 3,950 cm³ | -4.3% |
| Elastic modulus, major (Wel,y) | 3,240 cm³ | 3,550 cm³ | -8.7% |
| Second moment, minor (Iz) | 4,250 cm⁴ | 10,400 cm⁴ | -59.1% |
| Plastic modulus, minor (Wpl,z) | 672 cm³ | 1,060 cm³ | -36.6% |
| Radius of gyration, minor (iz) | 4.55 cm | 7.24 cm | -37.2% |
| Torsion constant (It) | 515 cm⁴ | 318 cm⁴ | +61.9% |
UB 457×191×161 to BS EN 10365:2017; HE 500 A to EN 10365 · Continental Steel. Difference is expressed relative to HE 500 A.
How to choose between them
On stiffness, HE 500 A has the larger second moment of area: 87,000 cm⁴ against 79,800 cm⁴, a difference of 8.3%. 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 500 A is the more efficient section: 25.5 against 23.4 cm³ per kg/m, 8.1% 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 500 A has 1060 cm³ of minor-axis plastic modulus against 672 cm³, 36.6% 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 4.1% weight.
In short, HE 500 A is the stronger section and HE 500 A 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.