W 12X79 vs H-300x300x13x20
W 12X79 is an W section from the American AISC Shapes Database; H-300x300x13x20 is the closest equivalent in the European (Continental) range. H-300x300x13x20 carries more bending: 2031 cm³ of plastic modulus against 1950.1 cm³, 4.0% more. W 12X79 is the lighter of the two at 117.6 kg/m against 125 kg/m, a saving of 5.9% on steel weight. Both are about 313 mm deep, so either fits the same construction zone.
| Property | W 12X79 W | H-300x300x13x20 MB & MC | Difference |
|---|---|---|---|
| Mass | 117.6 kg/m | 125 kg/m | -5.9% |
| Depth | 315 mm | 310 mm | +1.6% |
| Width | 307.3 mm | 303 mm | +1.4% |
| Web thickness | 11.9 mm | 13 mm | -8.5% |
| Flange thickness | 18.7 mm | 20 mm | -6.5% |
| Area | 149.7 cm² | 159 cm² | -5.8% |
| Second moment, major (Iy) | 27,555 cm⁴ | 28,130 cm⁴ | -2.0% |
| Plastic modulus, major (Wpl,y) | 1,950.1 cm³ | 2,031 cm³ | -4.0% |
| Elastic modulus, major (Wel,y) | 1,753.4 cm³ | 1,815 cm³ | -3.4% |
| Second moment, minor (Iz) | 8,991 cm⁴ | 9,282 cm⁴ | -3.1% |
| Plastic modulus, minor (Wpl,z) | 889.82 cm³ | 932 cm³ | -4.5% |
| Radius of gyration, minor (iz) | 7.75 cm | 7.64 cm | +1.4% |
| Torsion constant (It) | 159.8 cm⁴ | 200 cm⁴ | -20.1% |
W 12X79 to AISC Shapes Database v16.0; H-300x300x13x20 to Continental Steel. Difference is expressed relative to H-300x300x13x20.
How to choose between them
On stiffness, H-300x300x13x20 has the larger second moment of area: 28,130 cm⁴ against 27,555 cm⁴, a difference of 2.0%. 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 12X79 is the more efficient section: 16.6 against 16.2 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.
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 5.9% weight.
In short, H-300x300x13x20 is the stronger section and W 12X79 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.