W18×40 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.
W18×40 measures 17 7/8 in. deep with a 6 in. flange, on a 5/16 in. web and 1/2 in. flanges.
At 40 lb per foot it is one of the 23 W18 sizes, which run from 35 to 311 lb/ft.
For strong-axis bending its section modulus is Sx = 68.4 in³ and its moment of inertia Ix = 612 in⁴, with a plastic modulus Zx = 78.4 in³.
Detailing dimensions
| Depth (d) | 17 7/8" |
|---|---|
| Flange width (bf) | 6" |
| Web thickness (tw) | 5/16" |
| Flange thickness (tf) | 1/2" |
| k (detailing) | 1 3/16" |
| Workable gage (g) | 3 1/2" |
Section properties
| Weight | 40 lb/ft |
|---|---|
| Area (A) | 11.8 in² |
| Ix | 612 in⁴ |
| Sx | 68.4 in³ |
| Zx | 78.4 in³ |
| rx | 7.21 in |
| Iy | 19.1 in⁴ |
| Sy | 6.35 in³ |
| Zy | 10 in³ |
| ry | 1.27 in |
| J | 0.81 in⁴ |
Other W18 sizes
Same nominal size, different weight — useful when you are checking a substitution or a lighter section.
All W18 sizes and dimensions →
Similar weight wide-flange beams
Comparable 40 lb/ft sections in other wide-flange beam sizes.
Compare W18×40 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 W18×40 cut, formed, or fabricated? Huntington Steel & Supply Co.
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