W8×31 vs W8×35
A side-by-side comparison of two AISC wide-flange beams, 16th Edition. Detailing dimensions to the nearest 1/16 in.
W8×35 is the heavier section at 35 lb per foot, versus 31 for W8×31 (4 lb/ft more).
Both are nominally 8 in. deep.
W8×35 has the greater bending strength: section modulus Sx of 31.2 in³ versus 27.5, about 13% more.
| Property | W8×31 | W8×35 |
|---|---|---|
| Weight | 31 lb/ft | 35 lb/ft |
| Depth (d) | 8" | 8 1/8" |
| Flange width (bf) | 8" | 8" |
| Web thickness (tw) | 5/16" | 5/16" |
| Flange thickness (tf) | 7/16" | 1/2" |
| Area (A) | 9.13 in² | 10.3 in² |
| Moment of inertia (Ix) | 110 in⁴ | 127 in⁴ |
| Section modulus (Sx) | 27.5 in³ | 31.2 in³ |
| Plastic modulus (Zx) | 30.4 in³ | 34.7 in³ |
Open W8×31 in the interactive size chart →
Full detail: W8×31 · W8×35. Verify critical dimensions against the current AISC Steel Construction Manual before fabrication.
Browse more: size comparisons · Steel Beam Size Chart