> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Design a Cold-Formed Steel Stud or Column to AISI S100-16
> Design cold-formed steel studs and columns to AISI S100-16(2020) w/S2-20 with the Direct Strength Method and separate effective lengths per axis.
Design cold-formed steel studs and columns to AISI S100-16(2020) with independently specified strong-axis, weak-axis, and torsional effective lengths. Checks cover local, distortional, and global buckling via the Direct Strength Method. Axial load reactions link to connected beam and footing calculations so changes propagate automatically.
The Calcs.com **Cold-Formed Steel (CFS) Stud/Column** calculator uses a fixed analysis model: it treats the member as a **cantilever, fixed at the base and free at the top**. This is intentional and matches its purpose: a concentrically loaded stud or column standing up from a base connection with no restraint at the top.
If you enter a uniform lateral load *w* (for example, wind) over the member height *L*, the maximum moment the calculator reports will be **M = wL²/2** at the base, not the **wL²/8** you get from a pinned-pinned simple span. That is a factor of 4 difference, and it is the most common reason a hand calc on a braced curtain-wall stud disagrees with the CFS Stud/Column results.
## Method & scope
| Property | Detail |
| ---------------- | ------------------------------------- |
| Design standards | AISI S100-16(2020) w/S2-20, ASCE 7-16 |
| Regions | United States |
| What it checks | DSM axial capacity, Shear and bending |
#### Lateral loads and design checks
The calculator supports concentric axial design plus lateral (wind and seismic) loading. Enter wind and seismic tributary widths and design pressures to generate a lateral distributed-load table. This runs through the beam FEM solver and produces shear, moment and deflection diagrams alongside the axial load path.
With lateral load present, the calculator checks:
* Flexural strength (AISI S100-16 Cl F1/F2): yielding and global buckling, local buckling, distortional buckling
* Shear strength (Cl G2.1)
* Combined bending and shear at supports (Cl H2)
* Combined axial load and bending (Cl H1.2)
* Deflection, with user-defined absolute (default L/240) and span-ratio limits
Lateral inputs and checks only appear when lateral load is present, so concentric-axial-only members keep the existing workflow.
#### When the CFS Stud/Column calculator is the right tool
Use it when the member genuinely acts as a cantilever: fixed (or effectively fixed) at one end, free at the other, carrying axial load through its centroid with lateral load applied along its length. The base fixity and free top are baked into the analysis. You cannot switch them to pinned/roller inside this calculator.
#### When to use the CFS Beam calculator instead
A typical curtain-wall stud sits between a bottom track and a deflection track. It is braced top and bottom for out-of-plane wind, which is a **pinned/roller simple-span** condition, not a cantilever. For that case, use the **CFS Beam** calculator instead:
1. Open the **CFS Beam** calculator.
2. Set the **supports** to **pinned/roller**.
3. Set the **span** equal to the stud height.
4. Apply the lateral (wind) load along the span as you normally would on a beam.
The reported peak moment will then be **wL²/8**, matching the hand calc for a simply supported stud.
This is a modeling choice, not a units or input bug. If your CFS Stud/Column result looks about 4x higher than expected under lateral load, the mismatch is almost always **cantilever vs. simple-span**. Check which support condition actually applies to your member before adjusting inputs.
#### Calculation method
The Cold-Formed Steel Column calculator designs CFS studs and columns to AISI S100-16(2020) using the Direct Strength Method (DSM) for concentric axial loading. LRFD load combinations from ASCE 7/IBC determine the governing factored axial demand Pu.
##### DSM axial capacity
The nominal axial capacity is governed by the minimum of three limit states:
**Global buckling, φPne:** Critical elastic buckling loads are computed from the effective slenderness ratios **KxLx/rx** (strong axis), **KyLy/ry** (weak axis), and torsional slenderness about the shear center (using section properties Xo, Yo, distance from centroid to shear center). The least elastic buckling load governs, and the DSM global buckling equations convert this to the nominal global capacity **Pne**.
**Local buckling, φPnl:** Critical local buckling load Pncrl is determined from the section geometry. The DSM local-global interaction equations per AISI S100-16 Section C3.1 give the local buckling capacity relative to Pne:
**Pnl = DSM\_local(Pne, Pncrl)**
**Distortional buckling, φPnd:** The characteristic distortional buckling load Pncrd is derived from the section's distortional buckling mode. The DSM distortional column equations give Pnd independently of the global buckling result.
The governing capacity is:
**φPn = min(φPnl, φPnd, φPne)**
and the utilization check is **Pu / φPn ≤ 1.0** where φ = 0.85.
##### Shear and bending
This calculator covers concentric axial loading only. Shear capacity and beam-column interaction are not checked. If the column also carries significant bending moments (from eccentric reactions or lateral loads), those checks should be performed separately.
## 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).
#### US CFS Stud: Overview
#### US CFS Stud: Example
## Common questions
AISI S100-16(2020) with Supplement 2 (S2-20), using the Direct Strength Method (DSM) for local, distortional, and global (flexural and torsional-flexural) buckling of cold-formed steel columns. Load combinations follow ASCE 7/IBC LRFD provisions.
Member designation (from the CFS section database), column height, effective length factors K for the strong axis (Kx), weak axis (Ky), and torsion (Kt) along with their respective unbraced lengths, applied axial loads by load type (D, L, Lr, S, R, W, Ev, Eh), and optional live load reduction.
Global buckling: flexural buckling about the strong and weak axes and torsional-flexural buckling about the shear center, governed by the least slender effective length KL/r in each direction. Local buckling: DSM local interaction using the section's critical local buckling load. Distortional buckling: DSM distortional equations using the characteristic distortional buckling load. The governing capacity is the minimum across all three modes.
Yes, strong-axis, weak-axis, and torsional unbraced lengths are entered independently. This is the intended workflow for wall studs where sheathing provides weak-axis bracing at panel spacing but strong-axis and torsional bracing differ.
This calculator is designed for concentric axial loading only. For combined axial and bending in a CFS column, enter the axial demand and note that bending-moment checks are not included, they would need to be assessed separately or via a dedicated beam-column check.
Yes, axial load reactions from connected beam calculations link directly to this column. When loads change in any upstream beam, the column's axial demand updates automatically, no manual re-entry of reactions.
## Next steps
Design cold-formed steel beams to AISI S100-16(2020) w/S2-20 with the Direct Strength Method. Checks flexure, shear, web crippling and deflection.
Design hot-rolled steel beams to AISC 360-22 (ASD) with multiple spans and service-level loads. Checks bending, shear and three deflection limits.
Design wood columns and studs to NDS 2024 (ASD), with load linking from beams and a database of US wood sections.
## Method & scope
| Property | Detail |
| ---------------- | ------------------------------------- |
| Design standards | AISI S100-16(2020) w/S2-20, ASCE 7-16 |
| Regions | United States |
| What it checks | DSM axial capacity, Shear and bending |
#### Lateral loads and design checks
The calculator supports concentric axial design plus lateral (wind and seismic) loading. Enter wind and seismic tributary widths and design pressures to generate a lateral distributed-load table. This runs through the beam FEM solver and produces shear, moment and deflection diagrams alongside the axial load path.
With lateral load present, the calculator checks:
* Flexural strength (AISI S100-16 Cl F1/F2): yielding and global buckling, local buckling, distortional buckling
* Shear strength (Cl G2.1)
* Combined bending and shear at supports (Cl H2)
* Combined axial load and bending (Cl H1.2)
* Deflection, with user-defined absolute (default L/240) and span-ratio limits
Lateral inputs and checks only appear when lateral load is present, so concentric-axial-only members keep the existing workflow.
#### When the CFS Stud/Column calculator is the right tool
Use it when the member genuinely acts as a cantilever: fixed (or effectively fixed) at one end, free at the other, carrying axial load through its centroid with lateral load applied along its length. The base fixity and free top are baked into the analysis. You cannot switch them to pinned/roller inside this calculator.
#### When to use the CFS Beam calculator instead
A typical curtain-wall stud sits between a bottom track and a deflection track. It is braced top and bottom for out-of-plane wind, which is a **pinned/roller simple-span** condition, not a cantilever. For that case, use the **CFS Beam** calculator instead:
1. Open the **CFS Beam** calculator.
2. Set the **supports** to **pinned/roller**.
3. Set the **span** equal to the stud height.
4. Apply the lateral (wind) load along the span as you normally would on a beam.
The reported peak moment will then be **wL²/8**, matching the hand calc for a simply supported stud.
