W8×21 wide-flange beam
Detailing dimensions and section properties from the AISC Shapes Database, 16th Edition. Values are shown to the nearest 1/16 in. as they appear on a shop drawing.
W8×21 measures 8 1/4 in. deep with a 5 1/4 in. flange, on a 1/4 in. web and 3/8 in. flanges.
At 21 lb per foot it is one of the 13 W8 sizes, which run from 10 to 67 lb/ft.
For strong-axis bending its section modulus is Sx = 18.2 in³ and its moment of inertia Ix = 75.3 in⁴, with a plastic modulus Zx = 20.4 in³.
Detailing dimensions
| Depth (d) | 8 1/4" |
|---|---|
| Flange width (bf) | 5 1/4" |
| Web thickness (tw) | 1/4" |
| Flange thickness (tf) | 3/8" |
| k (detailing) | 7/8" |
| Workable gage (g) | 2 3/4" |
Section properties
| Weight | 21 lb/ft |
|---|---|
| Area (A) | 6.16 in² |
| Ix | 75.3 in⁴ |
| Sx | 18.2 in³ |
| Zx | 20.4 in³ |
| rx | 3.49 in |
| Iy | 9.77 in⁴ |
| Sy | 3.71 in³ |
| Zy | 5.69 in³ |
| ry | 1.26 in |
| J | 0.282 in⁴ |
Other W8 sizes
Same nominal size, different weight — useful when you are checking a substitution or a lighter section.
Similar weight wide-flange beams
Comparable 21 lb/ft sections in other wide-flange beam sizes.
Compare W8×21 with a nearby size
Detailing values are rounded to the nearest 1/16 in. per the AISC Steel Construction Manual. Verify critical dimensions against the current Manual before fabrication. Need W8×21 cut, formed, or fabricated? Huntington Steel & Supply Co.
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