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# Design a Steel Member (Design Only) to CSA S16:19
> Check a steel member for combined actions to CSA S16:19.
Member reactions link to connected column or footing calculations automatically, change a load and everything downstream updates. Design steel members to CSA S16:19 with combined axial and bending interaction, lateral-torsional buckling, and flexural buckling checks. Handles W-shapes, HSS, pipes, channels, and angles from the Canadian section library.
## Method & scope
| Property | Detail |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Design standards | CSA S16:19, NBCC 2015 |
| Regions | Canada |
| What it checks | Section classification, Flexural resistance and lateral-torsional buckling, Compressive resistance and column buckling, Combined actions interaction, Shear resistance, Tension resistance |
#### Calculation method
The Steel Member (Design Only) calculator to CSA S16:19 accepts factored design forces and runs all limit states resistance checks for the selected Canadian steel section under combined loading.
##### Section classification
Section class is determined from the plate element slenderness ratios for the flanges and web (CSA S16 Table 1). Class 1 (plastic), Class 2 (compact), Class 3 (non-compact), and Class 4 (slender) sections are identified. Class 1 sections can develop the full plastic moment. Class 2 sections reach but cannot maintain plastic moment under rotation. Class 3 sections are limited to first yield. Class 4 sections are not supported in this version and will return a failing result if selected.
##### Flexural resistance and lateral-torsional buckling
Clause 13.6 governs flexural resistance. The plastic moment capacity Mp = Z × Fy is the upper limit for Class 1 and 2 sections. Lateral-torsional buckling reduces the moment resistance when the unbraced length exceeds the yield moment boundary. The factored moment resistance Mr is:
* **Class 1 and 2, short segments**: Mr = φ × Mp (no LTB)
* **Inelastic LTB range**: Mr = 1.15 × φ × Mp × (1, 0.28 × Mp/Mu) ≤ φ × Mp
* **Elastic LTB**: Mr = φ × Mu
Where Mu is the elastic critical moment computed from the unbraced length, section torsional properties (J and Cw), and the moment gradient factor ω2. The ω2 factor accounts for non-uniform bending moment along the unbraced segment, increasing the effective moment resistance where the moment diagram is non-uniform.
For loads applied above the shear center (top flange loading), the load height adjustment from Cl. 13.6.1 reduces the elastic critical moment. This is activated by a user input.
##### Compressive resistance and column buckling
Clause 13.3 covers compressive resistance. The factored compressive resistance Cr depends on the slenderness ratio KL/r for each axis, yielding stress Fy, and the column curve parameter n (n = 1.34 for hot-rolled sections, n = 2.24 for welded sections). The governing slenderness ratio is used to compute the normalized slenderness λ:
**λ** = (KL/r) × sqrt(Fy / (π² × E))
**Cr = φ × Ag × Fy × (1 + λ^(2n))^(-1/n)**
For sections with one axis of symmetry (tees, channels), torsional-flexural buckling replaces simple flexural buckling and a modified effective slenderness ratio is used.
##### Combined actions interaction
Clause 13.8 interaction equations are the primary output. For members under combined axial compression and bending:
**interaction ratio** = Cf/Cr + (0.85 × U1x × Mfx/Mrx) + (β × U1y × Mfy/Mry) ≤ 1.0
Where Cf is the factored compressive force, Mfx and Mfy are factored moments, Mrx and Mry are the factored moment resistances (including LTB), U1x and U1y are moment amplification factors for P-delta effects within the member, and β equals 0.6 for I-shaped and T-shaped sections or 0.85 for box sections. Both the cross-section (Clause 13.8.2) and member stability (Clause 13.8.3) interaction equations are checked and the governing interaction ratio is reported.
##### Shear resistance
Clause 13.4 governs shear. The factored shear resistance Vr = φ × Aw × 0.66 × Fy for compact webs. For slender webs, shear buckling reduces Vr via the shear buckling parameter.
##### Tension resistance
Clause 13.2 covers tension. The calculator checks gross cross-section yielding (Tr = φ × Ag × Fy) and, where applicable, net section fracture (Tr = φu × Ane × Fu). Both limit states are evaluated and the lower controls.
## How to use it
Open it from **Run calc** in the About this calculator panel above.
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](/docs/running-calculations/checking-results/checks-references-conditions-assumptions).
Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export).
## Common questions
This calculator uses CSA S16:19, the 2019 edition of the Canadian standard for the design of steel structures. Load combinations reference NBCC 2015. Members are designed using limit states design (LSD), which is the Canadian equivalent of LRFD.
You provide the steel section (Canadian W, HSS, pipe, channel, or angle), member length, effective length factors or unbraced lengths for each axis, and the factored design forces, axial load, major- and minor-axis bending moments, and shear. Forces can be manually entered or linked from an upstream analysis calculator. A range of presets reduces repetitive data entry for common member types.
The calculator checks flexural capacity including lateral-torsional buckling (CSA S16 Clause 13.6), compressive resistance including flexural buckling (Clause 13.3), tensile resistance (Clause 13.2), shear resistance (Clause 13.4), and the combined axial plus bending interaction equations from Clause 13.8. Class 4 (slender) sections are not supported.
Yes. The Clause 13.8 interaction equations handle members under simultaneous axial force and bending about one or both axes. Both the strong-axis and weak-axis interaction ratios are evaluated and the controlling value is reported with the code reference.
You enter effective length factors for strong- and weak-axis buckling and the unbraced length for lateral-torsional buckling. The member is assumed to be part of a braced frame. Loads are assumed to be applied at or away from the shear center; the load height adjustment from CSA S16 Cl. 13.6.1 can be activated if loads are applied at the top flange.
Yes, the member calc receives reactions from upstream calculations (e.g. frame analysis) and passes base reactions to footing or base plate calculations. Changes propagate automatically through the load path.
## Next steps
Complete list of Calcs.com design calculators available for Canadian projects (CSA O86, CSA S16, NBCC, and related standards).
Design steel members to AISC 360-22 (LRFD). Input analysis forces to check combined axial, bending, and shear for US hot-rolled and HSS sections.
Design steel members to AISC 360-22 (ASD). Input analysis forces to check combined axial, bending, and shear interaction for US hot-rolled sections.
Link Design Only calculators to Truss Analysis and Portal Frame Analysis results to check member capacity against the analysis forces.
