Engineering Methodology
Standards, method, and scope.
OmniCFS follows published cold-formed-steel and general-design standards. Every calculation cites the section that governs it. This page lists the reference stack, the design-method summary, and the explicit scope boundaries of the tool.
All calculations follow AISI S100-16, AISI S240-20, AISI S400-20, and ASCE 7-22. Design checks use LRFD with φ factors from the applicable standard.
Every design check provides a full calculation trace with equation references, intermediate values, and the governing failure mode.
Results are independently reproducible. Each check shows the equation, inputs, and resistance factor that produced the verdict, so a licensed engineer can re-run the math.
Referenced standards
Design method
Every OmniCFS check uses the method and resistance factor shown below. Factors are current as of the cited standard edition.
| Check | Method | φ / limit | Reference |
|---|---|---|---|
| Axial Compression | LRFD | φc = 0.85 | AISI S100-16 §E2 |
| Flexural Strength | LRFD | φb = 0.90 | AISI S100-16 §F3 |
| Combined Axial + Bending | LRFD | §H1.2 interaction | AISI S100-16 §H1 |
| Web Crippling | LRFD | φw = 0.85 | AISI S100-16 §G5 (w/S2-20) |
| Bearing (stud-to-track) | LRFD | φ = 0.65 | AISI S100-16 §G4 |
| Built-Up Section (B2B) | LRFD | φc = 0.85 | AISI S100-16 §D1.1 |
| Connection (screw) | LRFD | φ = 0.50 | AISI S100-16 §J4 |
| Shear Wall (sheathed) | LRFD | φv from table | AISI S400-20 §E1 |
| Shear Wall Stiffness | 4-term eq. | δ = Σ(4 terms) | AISI S400-20 §E1.3.1 |
| Diaphragm Panel Shear | LRFD | φv = 0.65 | AISI S240-20 §B5.4.2 |
| Diaphragm Aspect Ratio | Geometry | L/W ≤ 4:1 | AISI S240-20 §E1.2 |
| Anchorage to Concrete | LRFD | Chapter 17 suite | ACI 318-19 §17 |
| Foundation Bearing | LRFD | φ = 0.65 | ACI 318-19 §22.8.3.2 |
| Soil Bearing | Service | q ≤ q_allow | IBC Table 1806.2 |
| Footing Flexure | LRFD | φ = 0.90 | ACI 318-19 §9.5 |
| Footing One-Way Shear | LRFD | φ = 0.75 | ACI 318-19 §22.5 |
| Wind Pressure | Directional | qz × GCp | ASCE 7-22 §26/§30 |
| Wind Serviceability | 10-yr MRI | IBC fn f factor | IBC §1609.3.2 fn f |
| Seismic Base Shear | ELF | Cs = SDS·Ie/R | ASCE 7-22 §12.8.1 |
| Seismic Vertical Dist. | Fx = Cvx·V | — | ASCE 7-22 §12.8.3 |
| Story Drift — Wind | Service | δ ≤ H/400 | IBC §1604.3 |
| Story Drift — Seismic | Cd-amplified | Table 12.12-1 | ASCE 7-22 §12.8.6 |
| P-Delta Stability | θ amplifier | θ < 0.10, max 0.25 | ASCE 7-22 §12.8.7 |
| Deflection (members) | Service | Table 1604.3 rows | IBC Table 1604.3 |
| Live-Load Reduction | Tributary area | 0.50 ≤ L/Lo ≤ 1.0 | ASCE 7-22 §4.7 |
| Steel Header (override) | LRFD | φb = 0.90 | AISC 360-22 Ch. F |
Current product envelope
This is the engineering boundary for normal OmniCFS use today. For plaza, data-center, prefab, commercial, or mid-rise opportunities, use the separate Scope Discovery page to classify the CFS assembly before treating it as future product scope.
- ✓1–4 story cold-formed steel light-frame residential
- ✓Single-family, duplex, townhome, fourplex, and barndominium templates
- ✓Height up to 50 ft inside the residential product envelope
- ✓Continental US projects with ZIP-derived wind, snow, frost, and seismic inputs
- ✓Risk Category I through IV
- ✓Site Class A, B, C, D, and E
- ✓3-story residential designs up to 140 mph wind
- ✓4-story non-fourplex designs up to 140 mph wind
- ✓4-story fourplex designs through 150 mph wind, 60 psf ground snow, and 10 ft story height
- ✓Exposure Categories B, C, and D with topographic factor
- ✓Seismic Design Category A through D
- ✓Residential occupancies (ASCE 7-22 Table 4.3-1)
- ✓Rectangular orthogonal lateral systems
- —Hot-rolled steel primary structure (AISC 360)
- —Wood framing (NDS)
- —Concrete or masonry primary structure
- —Commercial occupancies (B, M, F, S, A, E, I)
- —Pre-engineered metal buildings (PEMB)
- —5+ stories or podium transfer systems
- —Deep foundations, rock footings, and retaining walls over 4 ft
- —HVHZ or other cases requiring a different structural system
- —Alaska, Hawaii, and non-continental US hazard assumptions
- —Seismic Design Category E or F
- —Site Class F soft/liquefiable soils (site-specific analysis)
- —Irregular plan shapes (L / T / U / nonparallel systems)
- —Low-slope ponding analysis (slope < 1/4 in/ft)
- —Permit stamp or AHJ submission — handled by the licensed engineer
When the tool refers to a PE
Some conditions need project-specific engineering judgement, jurisdictional review, or release documentation the tool should not substitute for. When one is detected, the packet names the blocked system and the review path — never a silent pass.
- •Foundation anchorage package is ready for review but missing required release documentation
- •Slab or foundation load-transfer demand exceeds the automated capacity/detailing package
- •Soil bearing pressure exceeds the configured allowable value
- •Shear-wall, diaphragm, collector, or drift demand exceeds the automated residential design tables
- •Large openings require a support path outside the automated CFS bearing-stiffener/header strategy
- •Foundation seismic detailing falls outside the automated SDC C/D residential package
- •Site Class F or other site-specific geotechnical/seismic condition is selected
- •Roof slope is below 1/4 in/ft and requires ponding analysis
- •Non-orthogonal, asymmetric, commercial, podium, deep-foundation, HVHZ, SDC E/F, or 5+ story scope is detected
- •Fabrication geometry or package release documentation is incomplete for a production export
The complete list of assumptions underlying every OmniCFS calculation, organized by category with Conservative / Assumed flags.
Per-category verification checks, benchmark comparisons against published examples, and a downloadable Validation & Verification PDF.
Run a design and review the packet yourself
Every verdict in the output PDF cites the section listed above.