W8×40 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.
W8×40 measures 8 1/4 in. deep with a 8 1/8 in. flange, on a 3/8 in. web and 9/16 in. flanges.
At 40 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 = 35.5 in³ and its moment of inertia Ix = 146 in⁴, with a plastic modulus Zx = 39.8 in³.
Detailing dimensions
| Depth (d) | 8 1/4" |
|---|---|
| Flange width (bf) | 8 1/8" |
| Web thickness (tw) | 3/8" |
| Flange thickness (tf) | 9/16" |
| k (detailing) | 1 1/4" |
| Workable gage (g) | 5 1/2" |
Section properties
| Weight | 40 lb/ft |
|---|---|
| Area (A) | 11.7 in² |
| Ix | 146 in⁴ |
| Sx | 35.5 in³ |
| Zx | 39.8 in³ |
| rx | 3.53 in |
| Iy | 49.1 in⁴ |
| Sy | 12.2 in³ |
| Zy | 18.5 in³ |
| ry | 2.04 in |
| J | 1.12 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 40 lb/ft sections in other wide-flange beam sizes.
Compare W8×40 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 W8×40 cut, formed, or fabricated? Huntington Steel & Supply Co.
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