Bolt Connection Design (AISC)

civil

Designs and checks bolted connections per AISC 360 J3. Calculates bolt shear, tension, and combined capacity for single bolts and bolt groups. Supports A325, A490, SAE, and ISO bolt grades.

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Specification

Bolt specification or grade (e.g. 'A325', 'A490', 'A307'). Determines nominal tensile and shear stress per AISC Table J3.2. If omitted, defaults to A325, the most common structural bolt.

Nominal Diameter In

Nominal bolt diameter in inches. Standard structural sizes: 0.5, 0.625, 0.75, 0.875, 1.0, 1.125, 1.25, 1.5. Typical: 0.75 in for light connections, 0.875-1.0 in for moment connections. If omitted, defaults to 0.75 in.

Thread Series

Thread series for stress area lookup (e.g. 'UNC', 'UNF'). UNC is standard for structural bolts. If omitted, defaults to UNC.

Num Bolts

Total number of bolts in the connection group. Typical: 2-12 per connection. Must match bolt pattern geometry. If omitted, defaults to 4.

Num Shear Planes

Number of shear planes per bolt. Single shear = 1, double shear = 2. 1 for lap splice, 2 for double-angle or sandwich connections. If omitted, defaults to 1 (single shear).

Threads In Shear Plane

Whether bolt threads are included in the shear plane (N condition). True reduces shear capacity per AISC J3.6. False (X condition) uses the higher excluded-thread value. If omitted, defaults to True (threads included, conservative assumption).

Connection Type

Connection design method. Bearing-type uses bolt shear/bearing strength. Slip-critical prevents slip at service load using pretension and surface friction (AISC J3.8). If omitted, defaults to bearing-type design.

Hole Type

Hole type per AISC J3.3. Oversize and slotted holes reduce slip resistance (Table J3.1 factors: standard=1.00, oversize/short_slot=0.85, long_slot=0.70). If omitted, defaults to standard holes.

Applied Shear Kips

Total factored (LRFD) shear demand on the bolt group in kips. Recommended: enables shear demand/capacity ratio check. If omitted, only capacity is reported.

Applied Tension Kips

Total factored (LRFD) tension demand on the bolt group in kips. Recommended: enables tension demand/capacity ratio check and combined shear-tension interaction per AISC J3.7. If omitted, only capacity is reported.

Plate Thickness In

Connected plate thickness in inches. Recommended: enables bearing capacity check (2.4dtFu per AISC J3.10). If omitted, bearing capacity is not computed.

Plate Fu Ksi

Ultimate tensile strength of the connected plate in ksi. Typical: 58 ksi for A36, 65 ksi for A572 Gr. 50. If omitted, defaults to 58 ksi (A36 steel).

Reference data

This calculator pulls live values from the following engineering reference tables in the database.

bolt specifications
bolt thread dimensions
aisc bolt group coefficients

About this calculator

Bolt Connection Design (AISC) is part of the Engineering Database calculator suite. Each tool runs deterministic calculations against authoritative reference data and code-compliant methods, so results are reproducible and traceable to source standards.

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Reference data

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