New ZealandNZS 3404.1:1997 (Amdt 2)
Design hot-rolled steel columns and posts to NZS 3404.1:1997 for New Zealand projects. Checks cover axial section capacity, member buckling in compression, and combined axial-plus-bending interaction. Column loads link from beam reactions above to footing calculations below automatically.
Easily design and analyze steel columns and studs to NZS 3404.1:1997. With support for multiple end fixicities, and easy to understand traffic light checks for moment capacity, axial section capacity, and axial deformation, the Calcs.com steel column calculator enables the quick design of steel columns to New Zealand standards.
Method & scope
Calculation method
The Steel Column (NZS 3404:1997) calculator designs hot-rolled steel columns and posts using limit state design per NZS 3404.1:1997 (Amendment 2). It runs a first-order elastic analysis per Clause 4.4.2 to determine demands, then applies NZS 3404 capacity equations for all relevant limit states.Structural analysis
The calculator performs FEA on the column as a beam-column, resolving axial forces, bending moments, and deflections under applied loads. End conditions (pinned, fixed, roller) are specified at each support. Concentrated axial loads and distributed lateral loads can be applied at any height. The member is assumed to be of uniform cross-section along its full length. Interaction limit states are conservatively evaluated at the maximum individual demand in each span regardless of load case.Axial section capacity
Section capacity in compression is checked per NZS 3404.1:1997 Section 6: utilization = N / (phi * Ns) ≤ 1.0* where phi = 0.90 and Ns = kf * An * fy. The form factor kf accounts for local buckling of slender plate elements within the cross-section, consistent with the approach used in AS 4100.Member buckling capacity
Compression member buckling capacity follows NZS 3404.1:1997 Section 6: utilization = N / (phi * Nc) ≤ 1.0* Nc is derived from the member slenderness reduction factor alphac, which depends on the modified slenderness lambda_n and the member section constant alphab from NZS 3404 Table 6.3.3. Major- and minor-axis effective lengths are evaluated separately to identify the governing buckling axis.Flexural capacity
Moment member capacity (lateral-torsional buckling) follows NZS 3404.1:1997 Section 5: utilization = |M| / (phi * Mb) ≤ 1.0* Mb is determined from the reference buckling moment Ms and the slenderness reduction factor alphas per Section 5.6. Flange and web compactness classifications (compact, non-compact, slender) govern whether full plastic or reduced section capacity applies.Combined axial and bending
Combined axial compression and biaxial bending is checked per NZS 3404.1:1997 Section 8 interaction equations. Both major- and minor-axis moment demands are included. The amplified moment approach is applied consistent with the first-order analysis assumption.Deflection
Lateral deflection under service loads is calculated and reported alongside strength checks for serviceability review.Outputs
Results are displayed as color-coded utilization ratios for each limit state with NZS 3404.1:1997 clause references. Section properties, capacity factors, governing demands, and design actions are tabulated for straightforward report documentation.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 standard does this calculator use?
What design standard does this calculator use?
The calculator designs to NZS 3404.1:1997 (Amendment 2), the New Zealand Steel Structures Standard. It uses limit state design with capacity factors phi. NZS 3404 is closely based on AS 4100 and uses equivalent design provisions.
What are the key inputs?
What are the key inputs?
Key inputs include column height, end conditions (pinned, fixed, roller), axial design loads, distributed lateral loads, and effective length factors for major- and minor-axis buckling. Sections are selected from the New Zealand hot-rolled section database including UB, UC, RHS, SHS, and CHS sections.
What limit states does it check?
What limit states does it check?
The calculator checks axial section capacity (phi * Ns), member buckling capacity in compression (phi * Nc) for both axes, major- and minor-axis moment member capacity (phi * Mb), and combined axial compression plus biaxial bending interaction per NZS 3404.1:1997 Section 8.
How does NZS 3404 relate to AS 4100?
How does NZS 3404 relate to AS 4100?
NZS 3404.1:1997 is the New Zealand adaptation of AS 4100 and uses equivalent limit state design provisions. The main differences relate to New Zealand-specific section tables and load standard references to AS/NZS 1170. Engineers familiar with AS 4100 will find the design workflow essentially identical.
How do I set effective length factors?
How do I set effective length factors?
Major- and minor-axis effective length factors are entered directly as inputs. NZS 3404 Table 4.6.3 provides reference values for standard end conditions. For columns in moment frames, a rational buckling analysis or the effective length nomograph should be used to determine appropriate K-factors.
Can this calculator receive loads from a beam and pass axial load down to a footing calculation?
Can this calculator receive loads from a beam and pass axial load down to a footing calculation?
Yes, column axial load can be linked from beam reaction outputs above, and the resulting column base reaction links to a footing or base plate calculation below. Changes propagate automatically across the full load path.
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