AustraliaNew ZealandAS/NZS 4600:2018
Link analysis forces directly from a 3D model or beam analysis calculator, no re-entry required. Design cold-formed steel members to AS/NZS 4600:2018 using the Direct Strength Method, with checks for moment, shear, bearing, and combined actions across the full Australian CFS section library.
The Cold-Formed Steel Member Design Only calculator to AS/NZS 4600 is perfect for the fast capacity design of light gauge steel members where engineers already have analysis results available (for example, when forces are being taken from a 3D analysis model of a cold-formed steel structure). By enabling easy input of analysis forces on the member, the CFS member calculator enables the fast, optimized selection of cold-formed and light gauge steel members from our comprehensive library of of Australian CFS sections.
Method & scope
Calculation method
The Cold-Formed Steel Member calculator takes pre-computed analysis forces and applies AS/NZS 4600:2018 capacity design checks. The design method is the Direct Strength Method (DSM) from Clause 7, which uses elastic buckling analysis, specifically Finite Strip Method (FSM) signature curves built into the section library, to determine local, distortional, and global buckling loads.Section selection and configuration
You select a section from the comprehensive Australian CFS library (Cee, Zed, top-hat, hat, and custom shapes). The section configuration, Single, Back-to-Back, or Boxed, scales all capacity results by 1 or 2 as appropriate. The library stores the FSM-derived elastic buckling moments and compression loads needed for DSM without requiring you to run separate buckling software.Moment capacity
The moment section capacity phiM_s is the upper-bound capacity assuming perfect continuous restraint. It is compared against the maximum applied moment demand. Positive and negative moment member capacities account for lateral-torsional buckling: utilization = |M| / phiM_b ≤ 1.0* where phiM_b is governed by the lateral-torsional buckling load, the effective length between restraints, and the DSM strength curve. Separate checks are performed for positive and negative moment because top-flange and bottom-flange lateral bracing intervals are specified independently.Shear capacity
Shear capacity follows AS/NZS 4600:2018 Clause 3.3.4: utilization = |V| / phiV_v ≤ 1.0* When circular or rectangular web holes are present, a reduced shear capacity at holes is also reported, with the reduction factor q_s depending on hole size and spacing relative to web height.Bearing capacity
Bearing capacity at end supports and interior supports is checked for standard Cee and Zed sections. Bearing demand is the support reaction at the critical support location: utilization = R / phiR_b ≤ 1.0*Combined action checks
Two interaction checks guard against simultaneous high moment and high shear or moment and bearing: MV interaction = MV_int / MV_int,max ≤ 1.0 MR interaction = MR_intsum / 1.0 ≤ 1.0 These are evaluated at the location where both moment and shear or moment and bearing reaction are highest, per AS/NZS 4600:2018.Compression capacity
When the member carries axial compression, the compression section capacity (phiN_s) is checked first as an upper bound. The compression member capacity (phiN_c) accounts for local, distortional, and global buckling using the DSM strength curve. For combined bending and compression: MC interaction = MC_int ≤ 1.0How to use it
1
Open the calculator
Open it from Run calc in the About this calculator panel above. To start from a typical setup, choose one of the presets listed there.
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.
Available presets
Each preset opens the calculator with a typical setup already entered.Common questions
What design standard does this calculator use?
What design standard does this calculator use?
The calculator implements AS/NZS 4600:2018 using the Direct Strength Method (Clause 7) for local and distortional buckling of cold-formed steel members. The Appendix methods are not used.
What inputs does the calculator require?
What inputs does the calculator require?
You enter the factored bending moments (positive and negative), shear force, axial compression or tension, and bearing reactions for the member. These can be typed manually or linked from a Calcs.com analysis calculator. You also specify the section from the Australian CFS library, bracing intervals for strong axis, weak axis, and torsional restraints, and bearing lengths at supports.
What capacity checks does it perform?
What capacity checks does it perform?
The calculator checks moment section capacity, positive and negative moment member capacity (lateral-torsional buckling), shear capacity, shear capacity at web holes (when holes are present), bearing capacity at end and interior supports, combined bending and shear interaction, and combined bending and bearing interaction, all to AS/NZS 4600:2018.
Can it handle back-to-back or boxed sections?
Can it handle back-to-back or boxed sections?
Yes. The section configuration can be set to Single Section, Back-to-Back Section, or Boxed Section. All capacity equations are scaled accordingly, effectively doubling the capacity for paired sections.
When should I use this calculator versus the CFS Beam calculator?
When should I use this calculator versus the CFS Beam calculator?
Use this calculator when you already have analysis forces (moments, shear, axial) from a 3D analysis model or separate beam analysis, it skips structural analysis and goes straight to capacity design. Use the CFS Beam calculator when you need integrated load input, load combinations to AS 1170, and FEA-based moment and shear diagrams in the same calculation.
How does load linking work with this calculator?
How does load linking work with this calculator?
If you have a Calcs.com beam analysis or analysis with load cases calculator in the same project, you can link the member forces output directly into this calculator. Any change to loads upstream automatically updates the demand values here, so you do not have to manually re-enter forces after design iterations.
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