A449 Bolts — Strength and Allowable Capacity
ASTM high-strength fastener — not assigned AISC J3.2 Group A/B design values
An ASTM high-strength fastener, not an American Institute of Steel Construction (AISC) Group A or B structural bolt. Used where a high-strength bolt is needed outside the F3125 range: diameters over 1-1/2 in. and anchorage. AISC 360 designs it as a threaded part (Section A3.4, Table J3.2). Strength steps down with diameter.
Specified strengths
- Standard: ASTM A449 (Type 1)
- Tensile strength Fu: 120 ksi ≤ 1 in.; 105 ksi over 1 to 1-1/2 in.; 90 ksi over 1-1/2 to 3 in.
- Nominal tensile stress Fnt: 0.75 Fu (90 / 78.8 / 67.5 ksi)
- Nominal shear stress Fnv: 0.450 Fu threads included (54 / 47.3 / 40.5 ksi); 0.563 Fu threads excluded
A449 has no row of its own in AISC 360 Table J3.2. AISC 360 A3.4 permits it for bearing-type connections over 1-1/2 in. diameter and designs it as a threaded part: Fnt = 0.75 Fu, Fnv = 0.450 Fu (N) or 0.563 Fu (X), Ω = 2.00. Use the governing design specification; do not apply an arbitrary safety factor.
Allowable capacity by diameter
| Diameter | Ab (in²) | Fu (ksi) | A449 tension (kip) | A449 shear (kip) |
|---|---|---|---|---|
| 1/2" | 0.196 | 120 | 8.8 | 5.3 |
| 5/8" | 0.307 | 120 | 13.8 | 8.3 |
| 3/4" | 0.442 | 120 | 19.9 | 11.9 |
| 7/8" | 0.601 | 120 | 27.1 | 16.2 |
| 1" | 0.785 | 120 | 35.3 | 21.2 |
| 1-1/8" | 0.994 | 105 | 39.1 | 23.5 |
| 1-1/4" | 1.227 | 105 | 48.3 | 29.0 |
| 1-1/2" | 1.767 | 105 | 69.6 | 41.7 |
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 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
- Diameters over 1-1/2 in., where A325 stops. Bearing-type connections only; not permitted in slip-critical joints.
- Anchorage and equipment mounting rather than primary connections.
- Same chemistry class as A325 but without A325's quality and testing requirements, so it is not a drop-in substitute.
Identifying it in the field
Hex head with three radial lines (same as SAE Grade 5) plus manufacturer's mark; may also read "A449". No "A325" or "A490".
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