W 40X199 vs UB 1016×305×314
W 40X199 is an W section from the American AISC Shapes Database; UB 1016×305×314 is the closest equivalent in the UK Blue Book (SCI P363). UB 1016×305×314 carries more bending: 14800 cm³ of plastic modulus against 14240.4 cm³, 3.8% more. W 40X199 is the lighter of the two at 296.1 kg/m against 314.3 kg/m, a saving of 5.8% on steel weight. Both are about 991 mm deep, so either fits the same construction zone.
| Property | W 40X199 W | UB 1016×305×314 UB | Difference |
|---|---|---|---|
| Mass | 296.1 kg/m | 314.3 kg/m | -5.8% |
| Depth | 983 mm | 999.9 mm | -1.7% |
| Width | 401.3 mm | 300 mm | +33.8% |
| Web thickness | 16.5 mm | 19.1 mm | -13.6% |
| Flange thickness | 27.2 mm | 35.9 mm | -24.2% |
| Area | 379.4 cm² | 400 cm² | -5.2% |
| Second moment, major (Iy) | 620,185 cm⁴ | 644,000 cm⁴ | -3.7% |
| Plastic modulus, major (Wpl,y) | 14,240.4 cm³ | 14,800 cm³ | -3.8% |
| Elastic modulus, major (Wel,y) | 12,618 cm³ | 12,900 cm³ | -2.2% |
| Second moment, minor (Iz) | 28,928 cm⁴ | 16,200 cm⁴ | +78.6% |
| Plastic modulus, minor (Wpl,z) | 2,245 cm³ | 1,710 cm³ | +31.3% |
| Radius of gyration, minor (iz) | 8.76 cm | 6.37 cm | +37.5% |
| Torsion constant (It) | 761.7 cm⁴ | 1,260 cm⁴ | -39.5% |
W 40X199 to AISC Shapes Database v16.0; UB 1016×305×314 to BS EN 10365:2017. Difference is expressed relative to UB 1016×305×314.
How to choose between them
On stiffness, UB 1016×305×314 has the larger second moment of area: 644,000 cm⁴ against 620,185 cm⁴, a difference of 3.7%. 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, W 40X199 is the more efficient section: 48.1 against 47.1 cm³ per kg/m, 2.1% 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: W 40X199 has 2245 cm³ of minor-axis plastic modulus against 1710 cm³, 31.3% 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. W sections are specified to AISC Shapes Database v16.0 and UB to BS EN 10365:2017; 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 5.8% weight.
In short, UB 1016×305×314 is the stronger section and W 40X199 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.