A490 Bolts — Strength and Allowable Capacity
The high-strength alloy bolt, one step up from A325. Published as ASTM F3125 Grade A490. Used where the connection needs the capacity, with the extra care its hardness demands.
Specified strengths
- Standard: ASTM F3125 Grade A490
- Tensile strength Fu: 150 ksi
- Nominal tensile stress Fnt: 113 ksi
- Nominal shear stress Fnv: 68 ksi threads included (N); 84 ksi threads excluded (X)
Allowable capacity by diameter
| Diameter | Ab (in²) | A490 tension (kip) | A490 shear (kip) |
|---|---|---|---|
| 1/2" | 0.196 | 11.1 | 6.7 |
| 5/8" | 0.307 | 17.3 | 10.4 |
| 3/4" | 0.442 | 25.0 | 15.0 |
| 7/8" | 0.601 | 34.0 | 20.4 |
| 1" | 0.785 | 44.4 | 26.7 |
| 1-1/8" | 0.994 | 56.2 | 33.8 |
| 1-1/4" | 1.227 | 69.3 | 41.7 |
| 1-1/2" | 1.767 | 99.8 | 60.1 |
Allowable Stress Design (ASD), Ω = 2.00. Bearing-type, snug-tight, one shear plane, threads included (N), nominal shank area. For end-loaded connections with a fastener pattern longer than 38 in., multiply shear by 0.833 per American Institute of Steel Construction (AISC) 360 Table J3.2. Bearing, tearout, block shear, net section, prying and bolt interaction are separate checks. Fu is a material minimum, not an allowable stress.
Where it is used
- Heavy moment and bracing connections where A325 would drive the bolt count too high.
- Hot-dip galvanized A490 is not permitted (hydrogen embrittlement); mechanical galvanizing is also excluded. Only F2833 Grade 1 or F1136 Grade 3 zinc-flake coatings are allowed.
- Do not reuse A490 per Research Council on Structural Connections (RCSC) reuse restrictions. F2280 is the twist-off equivalent.
Identifying it in the field
Head marked "A490" plus the manufacturer's mark (F3125). Type 3 (weathering): "A490" underlined.
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