W 14X99 vs H-400x400x15x15
W 14X99 is an W section from the American AISC Shapes Database; H-400x400x15x15 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 2835 cm³ against 2802 cm³ of plastic modulus, a difference of 1.2%. H-400x400x15x15 is the lighter of the two at 140 kg/m against 147.3 kg/m, a saving of 5.2% on steel weight. H-400x400x15x15 is deeper, 388 mm against 360.7 mm, which matters where the floor zone is tight.
| Property | W 14X99 W | H-400x400x15x15 MB & MC | Difference |
|---|---|---|---|
| Mass | 147.3 kg/m | 140 kg/m | +5.2% |
| Depth | 360.7 mm | 388 mm | -7.0% |
| Width | 370.8 mm | 402 mm | -7.8% |
| Web thickness | 12.3 mm | 15 mm | -18.0% |
| Flange thickness | 19.8 mm | 15 mm | +32.0% |
| Area | 187.7 cm² | 178 cm² | +5.4% |
| Second moment, major (Iy) | 46,202 cm⁴ | 48,970 cm⁴ | -5.7% |
| Plastic modulus, major (Wpl,y) | 2,835 cm³ | 2,802 cm³ | +1.2% |
| Elastic modulus, major (Wel,y) | 2,572.8 cm³ | 2,524 cm³ | +1.9% |
| Second moment, minor (Iz) | 16,733 cm⁴ | 16,260 cm⁴ | +2.9% |
| Plastic modulus, minor (Wpl,z) | 1,370 cm³ | 1,237 cm³ | +10.8% |
| Radius of gyration, minor (iz) | 9.42 cm | 9.55 cm | -1.4% |
| Torsion constant (It) | 223.5 cm⁴ | 156 cm⁴ | +43.3% |
W 14X99 to AISC Shapes Database v16.0; H-400x400x15x15 to Continental Steel. Difference is expressed relative to H-400x400x15x15.
How to choose between them
On stiffness, H-400x400x15x15 has the larger second moment of area: 48,970 cm⁴ against 46,202 cm⁴, a difference of 5.7%. 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, H-400x400x15x15 is the more efficient section: 20.0 against 19.2 cm³ per kg/m, 3.8% 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 14X99 has 1370 cm³ of minor-axis plastic modulus against 1237 cm³, 10.8% 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. W sections are specified to AISC Shapes Database v16.0 and MB & MC to 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 5.2% weight.
In short, W 14X99 is the stronger section and H-400x400x15x15 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.