AustraliaAS4100:2020
Design and analyze bolt groups under shear, tension, and combined loading to AS 4100:2020. The elastic method distributes applied forces across an arbitrary bolt layout and checks all ULS and serviceability limit states for the critical bolt.
Easily design and analyze steel bolt connections with the Calcs.com Steel Bolt Calculator to AS 4100:2020. The calculator supports the design and analysis of an arbitrary number of steel bolts located at x and y locations, and supports the use of a wide variety of bolt categories and sizes. Detailing requirements must be checked by users.
Method & scope
Calculation method
The Steel Bolt (AS 4100:2020) calculator applies the elastic method to distribute applied loads across the bolt group and then verifies each limit state in AS 4100:2020 Clause 9 for the critical bolt.Load distribution
Applied design actions (shear V*, tension N*, in-plane moment M_z, and out-of-plane moment M_x) are resolved at the centroid of the bolt group. The centroid is computed assuming uniform bolt area. For in-plane loads, the elastic method resolves direct shear and torsional shear components using the polar moment of inertia I_z of the bolt group. The critical bolt is identified as the one carrying the highest resultant from the vector sum of all components.Bolt shear capacity (Clause 9.3.2)
Nominal shear capacity V_f per shear plane depends on the location of the shear plane relative to the threads:- Through the threaded portion: V_f = 0.62 × f_uf × A_s
- Through the unthreaded shank: V_f = 0.62 × f_uf × A_o
Bolt tensile capacity (Clause 9.3.3)
Nominal tensile capacity is based on the bolt tensile stress area: N_tf = A_s × f_uf Design capacity: N_d,tf = phi_b × N_tf. Utilization = N*_tf / N_d,tf ≤ 1.0Combined shear and tension (Clause 9.3.4)
For bolts loaded simultaneously in shear and tension, the interaction is governed by the circular interaction formula: Interaction ratio = (V_f / V_d,f)^2 + (N_tf / N_d,tf)^2 ≤ 1.0Ply bearing capacity (Clause 9.3.2)
Bearing failure of the connected ply is checked through two mechanisms:- Ply tearing (edge failure): V_b,t = a_e × t_p × f_up
- Ply bearing (interior): V_b,b = 3.2 × d_f × t_p × f_up
Serviceability friction checks (8.8/TF bolts)
For 8.8/TF friction bolts, the serviceability shear capacity is derived from the clamping force and slip factor: V_d,sf = phi_b,f × V_sf For combined serviceability shear and tension, the linear interaction formula applies: Utilization = V_sf / V_d,sf + N_sf / N_d,sf ≤ 1.0Capacity factors
- phi_b = 0.8 (bolt connections)
- phi_p = 0.9 (ply in bearing)
- phi_b,f = 0.7 (friction bolt serviceability)
How to use it
1
Open the calculator
Open it from Run calc in the About this calculator panel above.
2
Enter your inputs
Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See Checks, References, Conditions and Assumptions.
3
Review the results and export
Check the utilization of each governing check in the summary, then export a PDF report. See Views and Export.
Common questions
What design code does this calculator use?
What design code does this calculator use?
This calculator checks steel bolt connections to AS 4100:2020, Clause 9. It covers bolt shear and tensile capacity, ply bearing capacity, the combined shear-and-tension interaction check, and serviceability friction checks for high-strength bolts in the friction category.
What are the key inputs?
What are the key inputs?
Key inputs are the bolt category and size, number of shear planes (threaded and unthreaded), ply thickness, ply tensile strength, edge distance on the controlling ply, and the applied design actions, shear, tension, in-plane moment, and out-of-plane moment on the bolt group. Friction bolt checks also require the slip factor and serviceability load factor.
What does the calculator output?
What does the calculator output?
Outputs include the design shear capacity per bolt V_d,f, tensile capacity N_d,tf, ply bearing capacity V_d,b, and the combined shear-and-tension interaction ratio. For friction bolt configurations, the serviceability shear capacity V_d,sf and combined serviceability interaction ratio are also reported.
Can it handle bolt groups under combined shear and tension?
Can it handle bolt groups under combined shear and tension?
Yes. The calculator checks the circular interaction formula per AS 4100:2020 for bolts under simultaneous shear and tension: (V/V_d,f)^2 + (N/N_d,tf)^2 ≤ 1.0. The interaction ratio is the governing utilization for combined loading.
What bolt categories and sizes are supported?
What bolt categories and sizes are supported?
The calculator supports the bolt categories defined in AS 4100:2020, including 4.6/S, 8.8/S, 8.8/TB, and 8.8/TF categories, across standard metric bolt diameters. Bolt positions are entered as a table of X and Y coordinates, so any bolt group geometry is supported without restriction on the number of bolts.
Next steps
Australia & New Zealand Calculator Library
Complete list of Calcs.com design calculators available for Australian and New Zealand projects (AS 3600, AS 4100, AS 1720, AS/NZS 1170, and related standards).
Design a Weld Connection to AS 4100:2020
Analyze and design weld connections to AS 4100:2020, Cl 9.6. Checks fillet weld and butt weld capacity under combined shear and tension force per unit length.
Design a Steel Beam to AS 4100:2020
Design steel beams to AS 4100:2020 with multiple supports and loads. Floor- and roof-beam presets cut repetitive entry.
Design a Steel Angle Lintel to AS 4100:1998
Guide to the Steel Lintel calculator for steel angle lintels to AS 4100:2020.