W 30X173 vs HE 800 B
W 30X173 is an W section from the American AISC Shapes Database; HE 800 B is the closest equivalent in the European (Continental) range. HE 800 B carries more bending: 10200 cm³ of plastic modulus against 9946.9 cm³, 2.5% more. They weigh essentially the same, 257.5 kg/m and 262 kg/m. HE 800 B is deeper, 800 mm against 772.2 mm, which matters where the floor zone is tight.
| Property | W 30X173 W | HE 800 B HE | Difference |
|---|---|---|---|
| Mass | 257.5 kg/m | 262 kg/m | -1.7% |
| Depth | 772.2 mm | 800 mm | -3.5% |
| Width | 381 mm | 300 mm | +27.0% |
| Web thickness | 16.6 mm | 17.5 mm | -5.1% |
| Flange thickness | 27.2 mm | 33 mm | -17.6% |
| Area | 328.4 cm² | 334 cm² | -1.7% |
| Second moment, major (Iy) | 342,558 cm⁴ | 359,000 cm⁴ | -4.6% |
| Plastic modulus, major (Wpl,y) | 9,946.9 cm³ | 10,200 cm³ | -2.5% |
| Elastic modulus, major (Wel,y) | 8,865.4 cm³ | 8,980 cm³ | -1.3% |
| Second moment, minor (Iz) | 24,891 cm⁴ | 14,900 cm⁴ | +67.1% |
| Plastic modulus, minor (Wpl,z) | 2,015.6 cm³ | 1,550 cm³ | +30.0% |
| Radius of gyration, minor (iz) | 8.69 cm | 6.68 cm | +30.1% |
| Torsion constant (It) | 649.3 cm⁴ | 959 cm⁴ | -32.3% |
W 30X173 to AISC Shapes Database v16.0; HE 800 B to EN 10365 · Continental Steel. Difference is expressed relative to HE 800 B.
How to choose between them
On stiffness, HE 800 B has the larger second moment of area: 359,000 cm⁴ against 342,558 cm⁴, a difference of 4.6%. 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 (38.6 against 38.9 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.
The two diverge much more about the minor axis: W 30X173 has 2015.6 cm³ of minor-axis plastic modulus against 1550 cm³, 30.0% 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 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 a marginal amount of weight.
In short, HE 800 B is the stronger section and W 30X173 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.