UB 610×305×179 vs W 24X117
UB 610×305×179 is an UB section from the UK Blue Book (SCI P363); W 24X117 is the closest equivalent in the American AISC Shapes Database. UB 610×305×179 carries more bending: 5550 cm³ of plastic modulus against 5358.6 cm³, 3.6% more. W 24X117 is the lighter of the two at 174.1 kg/m against 179 kg/m, a saving of 2.8% on steel weight. Both are about 619 mm deep, so either fits the same construction zone.
| Property | UB 610×305×179 UB | W 24X117 W | Difference |
|---|---|---|---|
| Mass | 179 kg/m | 174.1 kg/m | +2.8% |
| Depth | 620.2 mm | 617.2 mm | +0.5% |
| Width | 307.1 mm | 325.1 mm | -5.5% |
| Web thickness | 14.1 mm | 14 mm | +0.7% |
| Flange thickness | 23.6 mm | 21.6 mm | +9.3% |
| Area | 228 cm² | 221.9 cm² | +2.7% |
| Second moment, major (Iy) | 153,000 cm⁴ | 147,346 cm⁴ | +3.8% |
| Plastic modulus, major (Wpl,y) | 5,550 cm³ | 5,358.6 cm³ | +3.6% |
| Elastic modulus, major (Wel,y) | 4,930 cm³ | 4,768.6 cm³ | +3.4% |
| Second moment, minor (Iz) | 11,400 cm⁴ | 12,362 cm⁴ | -7.8% |
| Plastic modulus, minor (Wpl,z) | 1,140 cm³ | 1,170 cm³ | -2.6% |
| Radius of gyration, minor (iz) | 7.07 cm | 7.47 cm | -5.4% |
| Torsion constant (It) | 340 cm⁴ | 279.7 cm⁴ | +21.6% |
UB 610×305×179 to BS EN 10365:2017; W 24X117 to AISC Shapes Database v16.0. Difference is expressed relative to W 24X117.
How to choose between them
On stiffness, UB 610×305×179 has the larger second moment of area: 153,000 cm⁴ against 147,346 cm⁴, a difference of 3.8%. 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, the two are equally efficient (31.0 against 30.8 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
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 W to AISC Shapes Database v16.0; 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 2.8% weight.
In short, UB 610×305×179 is the stronger section and W 24X117 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.