Bolted Connection Capacity Calculator
This calculator determines the design shear capacity and bearing capacity of a bolted connection in structural steel per AISC 360 LRFD (phi = 0.75). Two limit states control bolt connections: bolt shear failure (fracture through the bolt shank) and bearing failure (local crushing of the plate around the bolt hole). The governing (lesser) capacity of the two limit states is the connection's design strength. Enter the bolt diameter, nominal shear stress, plate thickness, plate ultimate strength, and number of bolts to find both capacities and the governing value.
Bolted connection design formulas (AISC 360 LRFD)
phi Rn (shear) = 0.75 × Fnv × (pi d²/4) × n
phi Rn (bearing) = 0.75 × 2.4 × Fu × d × t × n
Governing = min(shear, bearing)
These formulas assume single shear (one shear plane per bolt) and standard hole sizes with adequate edge distance. For double shear, multiply shear capacity by 2.
Design considerations
- Edge distance and spacing must meet AISC 360 Table J3.4 minimums to achieve full bearing capacity.
- Slip-critical connections (pretensioned bolts) have additional design requirements per AISC 360 Section J3.8.
- Block shear (Rn = 0.6 Fu Anv + Ubs Fu Ant) must also be checked and may govern in some connection geometries.
- Prying action in tension connections can significantly reduce bolt capacity and must be accounted for per AISC Design Guide 9.
Frequently asked questions
How is bolt shear capacity calculated?
Per AISC 360 Table J3.2, the nominal bolt shear stress Fnv depends on bolt grade and whether threads are in the shear plane. For A325-N bolts, Fnv = 54 ksi; for A490-N, Fnv = 68 ksi. Design shear strength = phi * Fnv * Ab * n, where Ab is the bolt area and n is the number of bolts. phi = 0.75 for shear.
What is bearing capacity of a bolt?
Bearing capacity is the force the hole edge can sustain before the plate crushes. Per AISC 360 Eq. J3-6a, for standard holes with clear distance Lc: Rn = 2.4 * Fu * d * t, where Fu is the plate ultimate stress, d is bolt diameter, and t is plate thickness. phi = 0.75.
What governs: shear or bearing?
The lesser of bolt shear capacity and bearing capacity governs the connection. Bearing often governs for thin plates or small edge distances. For thicker plates and adequate edge distance, bolt shear typically governs.
What bolt grades are common in US construction?
ASTM A325 (Fu = 120 ksi) and A490 (Fu = 150 ksi) high-strength bolts are most common in structural steel. A307 (low-carbon) bolts are used for minor connections. AISC 360 references A325 and A490 as the primary structural bolt standards.
Does the number of shear planes matter?
Yes. Single shear (one shear plane) provides capacity Fnv * Ab per bolt; double shear (two planes) provides 2 * Fnv * Ab per bolt. This calculator assumes single shear; multiply the result by 2 for double shear connections.
Official sources
- American Institute of Steel Construction: AISC 360 Specification for Structural Steel Buildings, Chapter J.
- ASTM International: ASTM A325 and A490 High-Strength Bolt Standards.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.