A325 vs A490 — Compared
The two high-strength structural bolts, side by side. A490 carries roughly 25% more in tension and shear; what it costs you is galvanizing, reuse, and a tighter installation tolerance.
Side by side
| A325 | A490 | |
|---|---|---|
| Standard | ASTM F3125 Grade A325 | ASTM F3125 Grade A490 |
| Tensile strength Fu | 120 ksi | 150 ksi |
| Nominal tensile stress Fnt | 90 ksi | 113 ksi |
| Nominal shear stress Fnv | 54 ksi | 68 ksi |
| Fnv, threads excluded (X) | 68 ksi | 84 ksi |
| Head marking | Head marked "A325" plus the manufacturer's mark (F3125). Three radial lines may also appear on heavy-hex heads. Type 3 (weathering): "A325" underlined. | Head marked "A490" plus the manufacturer's mark (F3125). Type 3 (weathering): "A490" underlined. |
| Galvanizing | Hot-dip (F2329) or mechanical permitted | Not permitted; F2833 Grade 1 / F1136 Grade 3 zinc-flake only |
| Reuse after pretensioning | Plain: with the engineer's approval per Research Council on Structural Connections (RCSC). Galvanized: no. | Not permitted by RCSC. |
Allowable capacity by diameter
| Diameter | Ab (in²) | A325 tension (kip) | A490 tension (kip) | A325 shear (kip) | A490 shear (kip) |
|---|---|---|---|---|---|
| 1/2" | 0.196 | 8.8 | 11.1 | 5.3 | 6.7 |
| 5/8" | 0.307 | 13.8 | 17.3 | 8.3 | 10.4 |
| 3/4" | 0.442 | 19.9 | 25.0 | 11.9 | 15.0 |
| 7/8" | 0.601 | 27.1 | 34.0 | 16.2 | 20.4 |
| 1" | 0.785 | 35.3 | 44.4 | 21.2 | 26.7 |
| 1-1/8" | 0.994 | 44.7 | 56.2 | 26.8 | 33.8 |
| 1-1/4" | 1.227 | 55.2 | 69.3 | 33.1 | 41.7 |
| 1-1/2" | 1.767 | 79.5 | 99.8 | 47.7 | 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.
Minimum pretension
| Diameter | A325 (kip) | A490 (kip) |
|---|---|---|
| 1/2" | 12 | 15 |
| 5/8" | 19 | 24 |
| 3/4" | 28 | 35 |
| 7/8" | 39 | 49 |
| 1" | 51 | 64 |
| 1-1/8" | 64 | 80 |
| 1-1/4" | 81 | 102 |
| 1-1/2" | 118 | 148 |
Minimum bolt pretension, AISC 360 Table J3.1 / RCSC Table 8.1. The installed tension a pretensioned or slip-critical joint has to reach, not a capacity.
Related
- ASTM A325 Reference
strengths, uses and head markings for ASTM A325
- ASTM A490 Reference
strengths, uses and head markings for ASTM A490
- Bolt Tensile & Shear Capacity Calculator
allowable tension and shear by grade, diameter and bolt count
- Fillet Weld Strength Calculator
capacity of a fillet weld by leg size, length and electrode