SCOTTSDALE COLD-FORMED STEEL TOOLBOX
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ScotCalc: Cold-Formed Steel Section Calculator
Required coil width and effective section properties for lipped C-channel studs and unlipped U-channel tracks.
Profile
Units
Lipped C-channel cross-section. All dimensions are outside-to-outside.
Required coil width
—in
Approximate starting blank width — see notes below before cutting production stock.
Calculation Breakdown
Web straight portion—
Both flanges (straight portions)—
Both lips (straight portions)—
Bend allowances (4 corners)—
Total developed length—
Notes & assumptions (read before production)
This result is a starting estimate, not a guaranteed blank size. It uses a centerline approximation: the bent corners are treated as if the steel follows an arc along the middle of its own thickness. This is the simplest, most common assumption and is accurate to within roughly ±2–3% for typical cold-formed light-gauge sections.
Why it's not exact.
When steel bends, the inside of the corner compresses and the outside stretches. The layer
that doesn't change length (the neutral axis) actually sits slightly toward the
inside of the bend, not at the centerline. The shift depends on material temper, bend radius
vs. thickness ratio, tooling, and springback — all of which vary shop to shop.
Engineers handle this with a "K-factor"; this calculator hardcodes K = 0.5
(centerline) for simplicity.
Recommended workflow. Use this number to estimate coil stock. Before running production, fabricate one sample part and measure the actual coil width consumed. If the predicted width is off, scale your stock width by the same delta on subsequent runs — it'll be consistent for that material/tooling combination.
Formulas used. Bend allowance per 90° corner: BA = (π/2)(R + t/2). Stud (4 bends): D + 2F + 2L − 8(R+t) + 4·BA. Track (2 bends): D + 2F − 4(R+t) + 2·BA. All linear inputs must use the same units.
More codes coming soon
Gross & effective section properties
Please select a design code from the dropdown above to view section properties and moment strengths.
Typical: 33 ksi (230 MPa) for lighter gauges, 50 ksi (345 MPa) for heavier.
Gross properties
| A | area | — |
| x̄ | centroid from back of web | — |
| Ix | moment of inertia, strong | — |
| Sx | section modulus, strong | — |
| rx | radius of gyration, strong | — |
| Iy | moment of inertia, weak | — |
| Sy | section modulus to lip face | — |
| ry | radius of gyration, weak | — |
Element slenderness (b/t)
| Web | — | — |
| Flange | — | — |
| Lip | — | — |
Effective area (uniform compression at f = Fy)
| Ae | effective area | — |
| Ae/A | section utilization | — |
Effective section moduli & moment strength (simplified, first-yield)
Strong axis (about x)
| Sx,eff | effective section modulus | — |
| Mnx | nominal moment, Sx,eff·Fy | — |
| φMnx | LRFD design (φ = 0.95) | — |
| Mnx/Ω | ASD allowable (Ω = 1.67) | — |
Weak axis (about y, lip in compression)
| Sy,eff | effective section modulus | — |
| Mny | nominal moment, Sy,eff·Fy | — |
| φMny | LRFD design (φ = 0.95) | — |
| Mny/Ω | ASD allowable (Ω = 1.67) | — |
Shear capacity (web shear, governs C / U sections)
| h | web flat depth = D − 2(R + t) | — |
| h/t | web slenderness | — |
| — | shear regime (kv = 5.34, unreinforced web) | — |
| Vn | nominal shear strength, Aw·Fv | — |
| φVn | LRFD design (φv = 0.95) | — |
| Vn/Ω | ASD allowable (Ωv = 1.60) | — |
Compression capacity (length-independent, local-buckling only)
| Ae | effective area (uniform compression at f = Fy) | — |
| Pn | nominal axial strength, Ae·Fy | — |
| φcPn | LRFD design (φc = 0.85) | — |
| Pn/Ωc | ASD allowable (Ωc = 1.80) | — |
The row above is the cross-section yielding / local-buckling limit only. For length-dependent global buckling (flexural & flexural-torsional), see the Length-dependent compression strength section below.
About these numbers. Gross properties use the centerline (line-element) method — accurate to ~1% of finite-thickness calcs for typical light-gauge sections. Effective values are single-pass approximations using uniform-compression effective-width formulas at f = Fy (and at f = Fn for the length-dependent compression check): stud flange k = 4 (treated as adequately edge-stiffened), lip and track flange k = 0.43 (unstiffened), with the web's compression half reduced for strong-axis bending. Global-buckling section properties (xo, ro, J, Cw) come from sectorial integration along the cross-section midline. Mn = Seff·Fy is the first-yield-with-effective-section moment; φ = 0.95 (LRFD) and Ω = 1.67 (ASD) per AISI S100-16 Section F1 for laterally braced flexural members. These results do not include lateral-torsional buckling of the beam, distortional buckling of the column, or Direct Strength Method interaction — they're for sanity-checking weight, sizing, capacity, and quoting, not a final design value. For deflection limits, combined-action checks, or distortional-buckling-sensitive sections, run the section through code-compliant software (RGS, ScotSteel).
Length-dependent compression strength (flexural & flexural-torsional global buckling)
Please select a design code from the dropdown above to view length-dependent compression capacity.
Effective lengths for flexural buckling about x (strong) and y (weak) axes, and for torsional buckling. Reduce KyLy and KtLt if the member is laterally / torsionally braced (e.g., by sheathing or strap bracing). Enter 0 to suppress buckling about that axis (fully braced).
| xo | centroid→shear-center offset (along x) | — |
| ro | polar radius of gyration about shear center | — |
| J | St. Venant torsion constant | — |
| Cw | warping constant | — |
| Fex | elastic flexural buckling, strong axis | — |
| Fey | elastic flexural buckling, weak axis | — |
| Fet | elastic torsional buckling | — |
| Fe,ft | elastic flexural-torsional buckling | — |
| Fe | governing elastic buckling stress | — |
| — | governing mode | — |
| λc | column slenderness, √(Fy/Fe) | — |
| Fn | nominal column stress | — |
| Ae(Fn) | effective area at f = Fn | — |
| Pn,g | global nominal, Ae(Fn)·Fn | — |
| φcPn,g | LRFD design (φc = 0.85) | — |
| Pn,g/Ωc | ASD allowable (Ωc = 1.80) | — |
Governing Pn = min(local, global) = — · φcPn = —
Download the complete step-by-step calculation report (HTML — opens in any browser; use File > Print > Save as PDF for a PDF copy).
Scottsdale Construction Systems
ScotCalc
Engineering Tools
Seismic Design Parameters
ASCE/SEI 7-16 & 7-22 site-adjusted values, sourced live from the USGS Seismic Design Web Service.
Querying USGS hazard service…
Lookup Failed
Site
Coordinates
Reference Standard
ASCE/SEI 7-16
Site D · RC II
Reference Standard
ASCE/SEI 7-22
Site D · RC II
Design Response Spectra
5%-damped horizontal design spectra, Sa(T) — code-edition comparison.
ASCE 7-16 — two-period spectrum
ASCE 7-22 — multi-period spectrum
I am raw html block.
Click edit button to change this html
- CFS Section Calculator
-
ScotCalc: Cold-Formed Steel Section Calculator
Required coil width and effective section properties for lipped C-channel studs and unlipped U-channel tracks.
ProfileUnitsLipped C-channel cross-section. All dimensions are outside-to-outside.Required coil width —inApproximate starting blank width — see notes below before cutting production stock.Calculation BreakdownWeb straight portion—Both flanges (straight portions)—Both lips (straight portions)—Bend allowances (4 corners)—Total developed length—Notes & assumptions (read before production)
This result is a starting estimate, not a guaranteed blank size. It uses a centerline approximation: the bent corners are treated as if the steel follows an arc along the middle of its own thickness. This is the simplest, most common assumption and is accurate to within roughly ±2–3% for typical cold-formed light-gauge sections.
Why it's not exact. When steel bends, the inside of the corner compresses and the outside stretches. The layer that doesn't change length (the neutral axis) actually sits slightly toward the inside of the bend, not at the centerline. The shift depends on material temper, bend radius vs. thickness ratio, tooling, and springback — all of which vary shop to shop. Engineers handle this with a "K-factor"; this calculator hardcodes
K = 0.5(centerline) for simplicity.Recommended workflow. Use this number to estimate coil stock. Before running production, fabricate one sample part and measure the actual coil width consumed. If the predicted width is off, scale your stock width by the same delta on subsequent runs — it'll be consistent for that material/tooling combination.
Formulas used. Bend allowance per 90° corner:
BA = (π/2)(R + t/2). Stud (4 bends):D + 2F + 2L − 8(R+t) + 4·BA. Track (2 bends):D + 2F − 4(R+t) + 2·BA. All linear inputs must use the same units.More codes coming soonGross & effective section properties
Please select a design code from the dropdown above to view section properties and moment strengths.Typical: 33 ksi (230 MPa) for lighter gauges, 50 ksi (345 MPa) for heavier.Gross properties
A area — x̄ centroid from back of web — Ix moment of inertia, strong — Sx section modulus, strong — rx radius of gyration, strong — Iy moment of inertia, weak — Sy section modulus to lip face — ry radius of gyration, weak — Element slenderness (b/t)
Web — — Flange — — Lip — — Effective area (uniform compression at f = Fy)
Ae effective area — Ae/A section utilization — Effective section moduli & moment strength (simplified, first-yield)
Strong axis (about x)
Sx,eff effective section modulus — Mnx nominal moment, Sx,eff·Fy — φMnx LRFD design (φ = 0.95) — Mnx/Ω ASD allowable (Ω = 1.67) — Weak axis (about y, lip in compression)
Sy,eff effective section modulus — Mny nominal moment, Sy,eff·Fy — φMny LRFD design (φ = 0.95) — Mny/Ω ASD allowable (Ω = 1.67) — Shear capacity (web shear, governs C / U sections)
h web flat depth = D − 2(R + t) — h/t web slenderness — — shear regime (kv = 5.34, unreinforced web) — Vn nominal shear strength, Aw·Fv — φVn LRFD design (φv = 0.95) — Vn/Ω ASD allowable (Ωv = 1.60) — Compression capacity (length-independent, local-buckling only)
Ae effective area (uniform compression at f = Fy) — Pn nominal axial strength, Ae·Fy — φcPn LRFD design (φc = 0.85) — Pn/Ωc ASD allowable (Ωc = 1.80) — The row above is the cross-section yielding / local-buckling limit only. For length-dependent global buckling (flexural & flexural-torsional), see the Length-dependent compression strength section below.
About these numbers. Gross properties use the centerline (line-element) method — accurate to ~1% of finite-thickness calcs for typical light-gauge sections. Effective values are single-pass approximations using uniform-compression effective-width formulas at f = Fy (and at f = Fn for the length-dependent compression check): stud flange k = 4 (treated as adequately edge-stiffened), lip and track flange k = 0.43 (unstiffened), with the web's compression half reduced for strong-axis bending. Global-buckling section properties (xo, ro, J, Cw) come from sectorial integration along the cross-section midline. Mn = Seff·Fy is the first-yield-with-effective-section moment; φ = 0.95 (LRFD) and Ω = 1.67 (ASD) per AISI S100-16 Section F1 for laterally braced flexural members. These results do not include lateral-torsional buckling of the beam, distortional buckling of the column, or Direct Strength Method interaction — they're for sanity-checking weight, sizing, capacity, and quoting, not a final design value. For deflection limits, combined-action checks, or distortional-buckling-sensitive sections, run the section through code-compliant software (RGS, ScotSteel).
Length-dependent compression strength (flexural & flexural-torsional global buckling)
Please select a design code from the dropdown above to view length-dependent compression capacity.Effective lengths for flexural buckling about x (strong) and y (weak) axes, and for torsional buckling. Reduce KyLy and KtLt if the member is laterally / torsionally braced (e.g., by sheathing or strap bracing). Enter 0 to suppress buckling about that axis (fully braced).
xo centroid→shear-center offset (along x) — ro polar radius of gyration about shear center — J St. Venant torsion constant — Cw warping constant — Fex elastic flexural buckling, strong axis — Fey elastic flexural buckling, weak axis — Fet elastic torsional buckling — Fe,ft elastic flexural-torsional buckling — Fe governing elastic buckling stress — — governing mode — λc column slenderness, √(Fy/Fe) — Fn nominal column stress — Ae(Fn) effective area at f = Fn — Pn,g global nominal, Ae(Fn)·Fn — φcPn,g LRFD design (φc = 0.85) — Pn,g/Ωc ASD allowable (Ωc = 1.80) — Governing Pn = min(local, global) = — · φcPn = —
Download the complete step-by-step calculation report (HTML — opens in any browser; use File > Print > Save as PDF for a PDF copy).
- Seismic Design Parameters
-
Scottsdale Construction SystemsScotCalcEngineering ToolsSeismic Design Parameters
ASCE/SEI 7-16 & 7-22 site-adjusted values, sourced live from the USGS Seismic Design Web Service.
Querying USGS hazard service…Lookup FailedSiteCoordinatesReference StandardASCE/SEI 7-16Site D · RC IIReference StandardASCE/SEI 7-22Site D · RC IIDesign Response Spectra5%-damped horizontal design spectra, Sa(T) — code-edition comparison.
ASCE 7-16 — two-period spectrumASCE 7-22 — multi-period spectrumI am raw html block.
Click edit button to change this html
