W18×55 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.
W18×55 measures 18 1/8 in. deep with a 7 1/2 in. flange, on a 3/8 in. web and 5/8 in. flanges.
At 55 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 = 98.3 in³ and its moment of inertia Ix = 890 in⁴, with a plastic modulus Zx = 112 in³.
Detailing dimensions
| Depth (d) | 18 1/8" |
|---|---|
| Flange width (bf) | 7 1/2" |
| Web thickness (tw) | 3/8" |
| Flange thickness (tf) | 5/8" |
| k (detailing) | 1 5/16" |
| Workable gage (g) | 3 1/2" |
Section properties
| Weight | 55 lb/ft |
|---|---|
| Area (A) | 16.2 in² |
| Ix | 890 in⁴ |
| Sx | 98.3 in³ |
| Zx | 112 in³ |
| rx | 7.41 in |
| Iy | 44.9 in⁴ |
| Sy | 11.9 in³ |
| Zy | 18.5 in³ |
| ry | 1.67 in |
| J | 1.66 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 55 lb/ft sections in other wide-flange beam sizes.
Compare W18×55 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 W18×55 cut, formed, or fabricated? Huntington Steel & Supply Co.
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