StructureCalcsS8X18.4
American Standard Beam · AISC Shapes Database v15.0 · United States
S8X18.4 is an American Standard beam 203.2 mm deep with a 101.6 mm wide flange, weighing 27.4 kg/m. The dimensions below are the published AISC Shapes Database v15.0 values; the drawing is generated from them.
S-shapes are American Standard beams with narrow, tapered flanges — the oldest rolled I-profile in the catalogue, still used for crane rails and work on older structures.
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Published dimensions
| Property | Metric | Imperial |
|---|---|---|
| Depth, d | 203.2 mm | 8.00 in |
| Flange width, bf | 101.6 mm | 4.00 in |
| Flange thickness, tf | 10.8 mm | 0.425 in |
| Web thickness, tw | 6.9 mm | 0.271 in |
| Mass per metre | 27.4 kg/m | 18.4 lb/ft |
| Area, A | 3,484 mm² | 5.40 in² |
| Second moment, Ix | 23,933,307 mm⁴ | 57.5 in⁴ |
| Second moment, Iy | 1,535,894 mm⁴ | 3.7 in⁴ |
Derived section properties
Integrated from the section's own outline including the root and toe radii, whose arcs are integrated analytically rather than approximated by facets. For S8X18.4 the computed area agrees with the published value to better than 0.01% and Ix to 0.13%. Where a value is also published, the published one above is the one to quote.
| Property | Value |
|---|---|
| Elastic modulus, Sx | 235,874 mm³ |
| Elastic modulus, Sy | 30,945 mm³ |
| Plastic modulus, Zx | 270,744 mm³ |
| Plastic modulus, Zy | 52,146 mm³ |
| Radius of gyration, rx | 82.9 mm |
| Radius of gyration, ry | 21.2 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