Bolt Shear Capacity Calculator
Free Bolt shear capacity Calculator for materials specifications projects. Enter dimensions to get material lists and cost estimates.
Reviewed by Abdullah, Technical Content Specialist
Formula
Rn = Fnv x Ab (per bolt per shear plane)
The nominal bolt shear strength (Rn) equals the nominal shear stress (Fnv) multiplied by the nominal bolt area (Ab). Fnv is 0.450 x Fu for threads included or 0.563 x Fu for threads excluded. Apply phi = 0.75 for LRFD or divide by omega = 2.00 for ASD.
Worked Examples
Example 1: Standard Beam Connection
Problem:Check 4 A325-N 3/4-inch bolts in single shear against 20,000 lbs applied load using LRFD.
Solution:Ab = pi x 0.75^2 / 4 = 0.4418 sq in\nFnv = 0.450 x 120,000 = 54,000 psi\nRn = 54,000 x 0.4418 = 23,856 lbs/bolt\nPhi-Rn = 0.75 x 23,856 = 17,892 lbs/bolt\nTotal = 4 x 17,892 = 71,568 lbs > 20,000 OK
Result:Total LRFD capacity of 71,568 lbs; DCR = 0.279 (passes)
Example 2: Heavy Truss Gusset Plate
Problem:Determine capacity of 6 A490-X 1-inch bolts in double shear.
Solution:Ab = pi x 1.0^2 / 4 = 0.7854 sq in\nFnv = 0.563 x 150,000 = 84,450 psi\nRn = 84,450 x 0.7854 = 66,307 lbs/bolt/plane\nTotal nominal = 6 x 2 x 66,307 = 795,684 lbs\nLRFD = 0.75 x 795,684 = 596,763 lbs
Result:Total LRFD capacity of 596,763 lbs in double shear
Frequently Asked Questions
What determines the shear capacity of a bolt?
Bolt shear capacity depends on the bolt diameter, material grade (ultimate tensile strength), whether the shear plane passes through the threaded or unthreaded portion, and the number of shear planes. The nominal shear stress is a fraction of the ultimate tensile strength: 0.450 times Fu when threads are in the shear plane, and 0.563 times Fu when threads are excluded. Larger bolts and higher grades provide greater shear resistance.
Why does it matter if threads are in the shear plane?
When the shear plane passes through the threaded portion of a bolt, the effective cross-sectional area is reduced by the thread roots, and the irregular geometry creates stress concentrations. This reduces the shear capacity by about 20 percent compared to shearing through the smooth unthreaded shank. Connection details should specify whether threads are included (N-type) or excluded (X-type), and the bolt length must be chosen accordingly to ensure the desired condition.
What is a double shear connection?
A double shear connection occurs when a bolt passes through three plates and the applied load creates two shear planes on the bolt. Common examples include a gusset plate sandwiched between two connection angles, or a clevis pin with two side plates. Double shear effectively doubles the bolt shear capacity compared to single shear because the load is shared across two cross-sections. Multi-shear-plane connections with more than two planes are also possible in specialized connections.
How do I calculate the load-bearing capacity of a beam?
Beam capacity depends on material, cross-section dimensions, span length, and support conditions. For a simple rectangular wood beam, bending strength = (F_b x b x d^2) / 6, where F_b is allowable stress, b is width, and d is depth. Always consult a structural engineer for critical applications.
References
Reviewed by Abdullah, Technical Content Specialist · Editorial policy