StructureCalcsHSS20X12X5/8
Rectangular HSS · AISC Shapes Database v15.0 · United States
HSS20X12X5/8 is a rectangular hollow structural section 508 × 305 mm with a 15.9 mm wall, weighing 189.6 kg/m. The dimensions below are the published AISC Shapes Database v15.0 values; the drawing is generated from them.
Rectangular HSS are cold-formed tubes that AISC tabulates on the design wall thickness (0.93 × nominal) — the note beside the derived table explains what that convention does to the numbers.
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Published dimensions
| Property | Metric | Imperial |
|---|---|---|
| Overall depth, d | 508 mm | 20.00 in |
| Overall width, b | 305 mm | 12.00 in |
| Wall thickness, t | 15.9 mm | 0.625 in |
| Mass per metre | 189.6 kg/m | 127.4 lb/ft |
| Area, A | 22,581 mm² | 35.00 in² |
| Second moment, Ix | 782,515,081 mm⁴ | 1,880.0 in⁴ |
| Second moment, Iy | 354,212,944 mm⁴ | 851.0 in⁴ |
Derived section properties
Integrated from the section's own outline including its outside corner radii, whose arcs are integrated analytically rather than approximated by facets. For HSS20X12X5/8 the computed area agrees with the published value to 0.03% and Ix to 0.08%. Where a value is also published, the published one above is the one to quote.
AISC tabulates hollow-section properties on the design wall (tdes = 0.93 tnom, per AISC 360), while the published mass reflects the nominal wall — which is why mass and area here differ by about 7% by convention, on every AISC hollow section.
| Property | Value |
|---|---|
| Elastic modulus, Sx | 3,078,252 mm³ |
| Elastic modulus, Sy | 2,326,696 mm³ |
| Plastic modulus, Zx | 3,769,574 mm³ |
| Plastic modulus, Zy | 2,651,377 mm³ |
| Radius of gyration, rx | 186.1 mm |
| Radius of gyration, ry | 125.3 mm |
S is the elastic modulus and Z the plastic modulus, following AISC 360. Australian and British practice reverse the letters.
Neighbouring sizes
Where these numbers come from
Published AISC Shapes Database v15.0 values. How StructureCalcs verifies its numbers · Understanding steel section properties · Query this section over the API