Design Code Checks

Run steel member capacity checks directly on analysed members within Structural FEA. Design checks are accessed through the Design Check tab in the Member Analysis dialog. Available to all users with monthly usage limits (3 anonymous, 10 free, unlimited Pro).

Supported Design Codes

Code	Region	Design Methods
AISC 360-16	United States	LRFD / ASD
AISC 360-22	United States	LRFD / ASD
Eurocode 3 (EN 1993-1-1)	Europe	Limit State
AS 4100:2020	Australia	Limit State
CSA S16-19	Canada	Limit State

Accessing the Design Check Tab

Run the analysis - design checks require valid analysis results.
Select a member in the 3D view.
Open Member Analysis - right-click the member and choose "Member Analysis", or click the Member Analysis button in the Properties panel.
Switch to the Design Check tab.

How It Works

The Design Check tab takes the internal forces from the FEA results and checks the selected member against the chosen design code. Forces are extracted automatically from the analysis - you do not need to input them manually.

The check uses the member's assigned section properties (from the library) and material properties, along with the internal force envelope or a specific load combination.

Combo Mode

Selected - Check against the currently selected load combination only.
Envelope - Check against all load combinations and report the governing result. This is the recommended mode for final design verification.

Design Parameters

The following parameters can be configured before running a check:

Effective Length Factors

Ky - Effective length factor for the weak/minor buckling mode (default 1.0)
Kz - Effective length factor for the strong/major buckling mode (default 1.0)
KLT - Effective length factor for lateral-torsional buckling (default 1.0). Not shown for CHS and SHS, which have no lateral-torsional mode (AS 4100 takes M_b = M_s), or for any hollow section under EC3.
Kt (compression buckling) - Independent torsional/flexural-torsional effective length factor for applicable steel sections, including EC3 angles under 6.3.1.4 and AISC angles requiring E4. The torsional effective length is Kt x L (default 1.0); verify the actual torsional restraint. This factor is independent of Ky/Kz and KLT/Lb, and remains active with continuous lateral bending restraint.

The effective buckling length is K × L, where L is the member length. Code-axis symbols vary between standards.

Lateral Restraint

Continuous Restraint - The top flange is continuously restrained along the full length, for example by a concrete slab or welded metal deck. Sagging has no lateral-torsional buckling reduction; hogging (bottom flange in compression) is still checked for lateral-torsional buckling using KLT. Set KLT = 0 only if the bottom flange is also braced. For angles, the whole member is treated as continuously restrained and the lateral-torsional buckling reduction is bypassed.

Moment Factor Override

Each design code uses a moment gradient factor to account for non-uniform bending moment distributions along the member:

AISC 360-16 / AISC 360-22: C_b (Eq. F1-1)
Eurocode 3: C₁ (NCCI SN003; general quarter-point expression of López, Yong and Serna (2006) for other diagrams on I-sections and channels)
AS 4100:2020: α_m (Cl 5.6.1.1)
CSA S16-19: ω₂ (Cl 13.6)

By default, the factor is computed automatically from the member's moment diagram. You can override it if you have a specific value from your engineering judgement or a more detailed analysis.

Tension Rupture Inputs

Hot-rolled steel checks accept a member net tension area. AISC and CSA also accept a shear-lag/effective-net factor, while AS 4100 accepts k_t. Blank net area defaults to gross area; the member engine does not derive holes, staggered paths, or connection geometry. A blank AS 4100 k_t or CSA U uses the code's eccentric-connection value for the section family (AS 4100 Table 7.3.2; CSA Cl 12.3.3.2 lowest value), shown as the input placeholder; enter 1.0 only when every element is connected.

Code-Specific Options

Load Height (EC3, AS4100, CSA) - Whether the load is applied at the shear centre or the top flange. Top flange loading is more conservative for lateral-torsional buckling. Shown only for sections whose LTB check reads it (CSA: I-shapes, channels, non-square RHS, and tees; AS4100: I-shapes, channels, non-square RHS, tees, and angles while Table 5.6.3 factors are active).
AS4100 imported metadata - k_f, α_b, and β_x are normally derived from the section and code rules. Imported models may carry explicit values for replaying known section metadata; these are not ordinary required manual inputs.
M_cr / k_c,LT (EC3) - Optional elastic critical moment override for EC3 LTB, plus a Table 6.6 correction factor for the 6.3.2.3 I/H method only.
Cantilever (AISC, AS4100, CSA, EC3) - Auto (default) follows the model and shows the detection, e.g. "Auto (detected: cantilever, held at Node A)"; Span and Cantilever override it. For an effective cantilever AISC forces C_b = 1.0 and CSA ω₂/ω₃ = 1.0 (the override is hidden), EC3 requires a supplied M_cr, and AS 4100 provides load type selection (end moment, point load, or UDL).
AS4100 Table 5.6.3 - Segment restraint, load position, load height, and rotation factors apply while the table-factor control is active (the default for untouched I-shapes, channels, RHS, tees, and angles); otherwise KLT is treated as the final L_e/L factor.
AS4100 channel FTB brace confirmation - Confirms the hot-rolled channel is braced about its minor principal axis, which triggers the engine-local Clause 6.3.3 FTB force capacity using the referenced equations, the 0.85 reduction, and phi=0.90. An unbraced hot-rolled channel remains on ordinary flexural buckling.
Buckling mode y-y / z-z (EC3) - For compression members checked under Clause 6.3.3 (equal-flange I, RHS, CHS). On a linear analysis, Sway uses C_m = 0.9 (Table B.3 note) and requires sway buckling lengths (K > 1.0); Non-sway uses the moment diagram; Unspecified uses the larger. Cantilevers always use 0.9. Not used with P-Delta.
EC3 National Annex and partial factors - Automatic, CEN recommended or UK NA (Automatic follows the section library country). Partial factors and η are prefilled from the annex and can be overridden; for another country's annex, choose CEN and enter its factors.
Design Method (AISC) - Toggle between LRFD and ASD.

Results

After running a check, the Design Check tab displays:

Overall Status - one of the result statuses below, with a colour-coded indicator.
Utilisation Ratio - The governing demand-to-capacity ratio as a percentage.
Governing Check - The name and clause of the most critical check.
Governing Combination - Which load combination produces the worst result (in envelope mode).

Individual Check Results

A detailed table lists every capacity check performed:

Check Name - e.g. "Lateral-Torsional Buckling (F2)", "Axial Compression (E3)"
Demand - The applied force or moment from the analysis
Capacity - The calculated member resistance
Ratio - Demand / Capacity (values above 1.0 indicate failure)
Status - the status of that check (see below)

Result Status

PASS - every performed check is within its capacity.
PASS (partial) - the performed checks pass, but one or more checks that apply to this member are not performed by the engine. They are listed under Additional verification required; verify them separately. A check that is not performed never changes PASS to FAIL.
WARNING - the governing utilisation is above 0.9, or a performed check reports a warning.
FAIL - a performed check exceeds its capacity (ratio above 1.0).
INCOMPLETE - a required input is missing or invalid, for example a load combination that is not tagged ULS or SLS where the design code needs it, missing material design data, or non-finite analysis results. No capacity is reported for the blocked checks. The headline reads Not assessed when no check could be performed.
OUT OF SCOPE - the member, section or material cannot be evaluated by this engine, for example an unsupported section shape or orientation. No capacity is reported.

Checks Performed

Depending on the design code and section type, checks include:

Section classification (compact/non-compact/slender or Class 1 to 4)
Axial tension and compression, including code-specific member stability checks
Flexure - yielding, lateral-torsional buckling, flange and web local buckling
Shear - web yielding
Torsion - for closed hollow sections (RHS/SHS/CHS)
Combined actions - axial + biaxial bending interaction

PDF Hand Calculations

Export a detailed PDF for the published design checks and visible blocking scope results. The handcalc report includes section properties, applied forces, design settings, available intermediate values, clause references, and final capacity ratios for independent engineering review.

Under the design actions, a Design action basis block states where the actions came from:

Analysis: the analysis that produced the forces, for example linear static (first order) or P-Delta (second order).
Combination: one line for each load combination the calculation cites, written as its factor formula with your load case titles, for example ULS1 (Combo: 3) [ULS] = 1.35×G + 1.50×Q - 0.75×W. Combinations that no check uses are not listed.
Standalone design calculators have no structural analysis, so their reports say "User-entered design actions (no structural analysis)".

The effective length table has a Source column, and the K factor rows in Design Settings show the same source. A source is one of: Model geometry (member length), Member setting (a value you entered on the member), Default (the factor was left blank and the engine used the stated default, usually 1.0), Calculator input, or Computed with the clause used, such as the AS 4100 Clause 5.6.3 LTB effective length. When the source cannot be established the report says Not recorded rather than guessing. Buckling-analysis K factors are not applied to design checks.

Warnings

The design engine may produce advisory warnings alongside the check results. These highlight situations where the results should be reviewed with care:

Slenderness ratio exceeds code limits
Section classification changes under combined loading
Effective width reductions applied for slender elements
Torsion not checked for open sections (warping torsion not implemented)
A cantilever (detected on Auto or selected) forces AISC C_b = 1.0 and CSA ω₂/ω₃ = 1.0; choose Span only when applying a rational cantilever LTB result through the manual inputs
EC3 cantilever LTB needs a supplied elastic-buckling M_cr for the actual free-end restraints; C₁ alone does not establish them

Supported Section Types

All hot-rolled steel design codes support the following section shapes from the library:

I-Sections - Rolled and welded (UB, UC, W-shapes, doubly-symmetric and mono-symmetric)
Channels - PFC, C-shapes
Tee Sections - BT, WT
Rectangular Hollow Sections - RHS, SHS
Circular Hollow Sections - CHS, pipe
Angles - Equal and unequal

Limitations

Warping torsion for open sections is not checked - torsion checks apply to closed hollow sections only.
Compression effective length factors default to 1.0 and must be set by the user. The FEA does not automatically calculate system-level buckling lengths.
Support, point-load, and connection-region local checks are not automatically derived from the model. Examples include concentrated-force web checks, bearing stiffeners, doubler plates, local flange bending, and web crippling.
Connection design is separate from member design. A passing member check does not verify bolt holes, connection net sections, welds, bolts, brace attachments, or transfer-region detailing unless a separate connection check is run.
Brace and restraint design is separate from member design. The check uses effective lengths, unbraced lengths, load-height settings, and full-restraint flags as inputs; it does not verify brace strength, stiffness, diaphragm action, or restraint connection capacity.
Compound member detailing such as laced, battened, back-to-back, or multi-component member interconnections is not automatically generated unless stated in the code-specific documentation.
Built-up and fabricated section support varies by code and section type. AISC includes selected built-up I-shape and plate-girder provisions; verify the code-specific documentation before relying on fabricated-section results.
Ponding, fatigue, fire, corrosion, composite action, seismic detailing, and serviceability limits are outside the steel member-strength checks unless covered by another tool or workflow.

Standalone Design Calculators

The same design engines are also available as standalone calculators, where you can input member forces directly without building a full FEA model: