AISC Bolt Capacity Table
Quick reference for AISC 360 structural bolt capacities per LRFD design (phi = 0.75 for shear, phi = 0.75 for tension).
Bolt capacities below are based on nominal bolt strength from AISC 360-22 Table J3.2. Values assume threads included in shear plane (N condition) or threads excluded (X condition) as noted.
A325 Bolt Shear Capacity (phiRn, kips) — Single Shear
Bolt material: ASTM F3125 Grade A325, Fnv = 54 ksi (threads included), 68 ksi (threads excluded).
| Bolt Diameter | Gross Area (in²) | Threads Included (N) | Threads Excluded (X) |
|---|---|---|---|
| 5/8" | 0.307 | 12.5 | 15.7 |
| 3/4" | 0.442 | 17.9 | 22.6 |
| 7/8" | 0.601 | 24.4 | 30.7 |
| 1" | 0.785 | 31.9 | 40.1 |
| 1-1/8" | 0.994 | 40.3 | 50.8 |
| 1-1/4" | 1.227 | 49.8 | 62.6 |
| 1-3/8" | 1.485 | 60.2 | 75.8 |
| 1-1/2" | 1.767 | 71.7 | 90.2 |
A490 Bolt Shear Capacity (phiRn, kips) — Single Shear
Bolt material: ASTM F3125 Grade A490, Fnv = 68 ksi (threads included), 84 ksi (threads excluded).
| Bolt Diameter | Gross Area (in²) | Threads Included (N) | Threads Excluded (X) |
|---|---|---|---|
| 5/8" | 0.307 | 15.7 | 19.4 |
| 3/4" | 0.442 | 22.6 | 27.9 |
| 7/8" | 0.601 | 30.7 | 37.9 |
| 1" | 0.785 | 40.1 | 49.5 |
| 1-1/8" | 0.994 | 50.8 | 62.7 |
| 1-1/4" | 1.227 | 62.6 | 77.3 |
| 1-3/8" | 1.485 | 75.8 | 93.6 |
| 1-1/2" | 1.767 | 90.2 | 111.4 |
A325 Bolt Tension Capacity (phiRn, kips)
AISC 360-22 Table J3.2: Fnt = 90 ksi for A325.
| Bolt Diameter | Tensile Stress Area (in²) | phiRn (kips) |
|---|---|---|
| 5/8" | 0.226 | 15.3 |
| 3/4" | 0.334 | 22.6 |
| 7/8" | 0.462 | 31.2 |
| 1" | 0.606 | 41.0 |
| 1-1/8" | 0.763 | 51.6 |
| 1-1/4" | 0.969 | 65.5 |
| 1-3/8" | 1.160 | 78.5 |
| 1-1/2" | 1.405 | 95.1 |
Notes on Usage
- phi factor: 0.75 for both shear and tension (LRFD)
- Bearing capacity governs at low edge distances — check separately per Table J3.6
- Bolt pretension for slip-critical connections: refer to AISC 360 Table J3.1
- Combined tension + shear: Interaction equation per AISC 360 Section J3.7 applies when both are present
- For ASD, divide phiRn by 1.50 (omega = 2.00)
Frequently Asked Questions
What is the difference between A325 and A490 bolts? A325 (ASTM F3125 Grade A325) has Fnt = 90 ksi in tension and Fnv = 54 ksi in shear (threads included). A490 (ASTM F3125 Grade A490) has Fnt = 113 ksi in tension and Fnv = 68 ksi in shear — roughly 25% stronger. A490 bolts must not be galvanized and require special attention in slip-critical connections. Use A325 for most structural connections; A490 where bolt count or size would otherwise be excessive.
What does "threads included" vs "threads excluded" mean? The shear plane cuts through the threaded portion of the bolt (N condition, threads included) or the unthreaded shank (X condition, threads excluded). The threaded area is smaller than the gross area, so N-condition capacity is lower. Most standard connections use N-condition (threads are in the shear plane by default); X-condition requires deliberate detailing to ensure threads are outside the shear plane, confirmed by inspection.
When does bolt bearing capacity govern over bolt shear? Bearing capacity (phi × Rn = phi × 2.4 × Fu × d × t) governs when the edge distance or plate thickness is small relative to the bolt diameter. Common trigger: edge distance < 1.5d or thin gusset plates. AISC 360 Table J3.6 gives bearing values; always check bearing at each connected ply separately. For connections with standard holes and adequate edge distance, shear typically governs.
How do I account for combined tension and shear in a bolt? Use AISC 360 Section J3.7. When shear stress frv exceeds 20% of the bolt shear capacity, the available tension capacity is reduced. The interaction equation: F'nt = 1.3×Fnt − (Fnt/phi×Fnv) × frv ≤ Fnt. Check this for bracket plates, moment end plates, and any connection where the bolt load has both a horizontal and vertical component.
What phi factor applies to bolt capacity in LRFD? AISC 360 uses phi = 0.75 for both bolt shear and bolt tension. For slip-critical connections (where the joint must not slip at service load), a separate check uses phi = 1.0 for Class A faying surfaces or phi = 1.13 for Class B, applied to the slip resistance — not the bolt strength.
How many 3/4 in A325 bolts do I need for a 100-kip shear connection? A single 3/4 in A325 bolt in single shear with threads included (N condition) has φRn = 17.9 kips. For 100 kips: n = 100 / 17.9 = 5.6 → use 6 bolts minimum. Always check bearing on the connected material separately. For A36 plate (Fu = 58 ksi) with standard holes and adequate edge distance: φRn_bearing = 0.75 × 2.4 × 58 × 0.75 × t per bolt. For 3/8 in plate: 0.75 × 2.4 × 58 × 0.75 × 0.375 = 29.3 kips/bolt — bearing controls only if the plate is very thin.
What is the A490 tension capacity for a 1 in bolt, and when should I use A490? A 1 in A490 bolt has φRn in tension = 0.75 × 113 × 0.606 = 51.4 kips (using the tensile stress area of 0.606 in²). Compare to A325: 0.75 × 90 × 0.606 = 41.0 kips — A490 is 25% stronger in tension. Specify A490 when bolt count is limited by geometry (e.g., moment end plates with fixed bolt pattern), when bolt diameter is constrained, or where A325 bolts would require an impractically large group to resist high tension demands such as in rigid moment connections.
How do I calculate double-shear bolt capacity? For double shear, multiply the single-shear capacity by 2. A 7/8 in A325 bolt in double shear (threads included): φRn = 2 × 24.4 = 48.8 kips. Double shear occurs in gusset plates sandwiched between two connection elements (e.g., a brace-to-gusset connection). Note that bearing must also be checked on each individual ply — the bearing capacity is not doubled unless each ply is thick enough to develop its own bearing resistance.
Run This Calculation
→ Bolted Connections Calculator — full bolt group capacity with shear, bearing, block shear, and eccentric bolt group checks per AISC 360.
→ Gusset Plate Calculator — gusset plate and weld group design including bolt layout and block shear at connections.
Calculate Bolt Group Capacity
Use the Bolted Connection Calculator to check bolt group capacity with full AISC 360 derivation steps, including instantaneous centre of rotation for eccentric bolt groups.
Related pages
- Bolt Torque Chart — A325, A490, Metric 8.8/10.9, SAE Gr5/Gr8
- Bolt Spacing & Edge Distance — Minimum Requirements
- Bolt Hole Sizes — AISC Standard, Oversize & Slotted
- Steel Connection Design — Bolted and Welded Limit States
- Bolted Connections Calculator — full bolt group capacity with eccentric bolt group checks
- Gusset Plate Calculator — gusset plate and bolt group design including block shear
- Steel Grades Reference — A36, A572, A992 material properties for connection plates
- Bolt grades reference
- AISC bolt hole sizes
- AS 4100 Bolt Group Design
- Steel Fy and Fu reference table
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