Sections

Sections define the cross-sectional geometry of structural members. The section properties determine how a member resists bending, shear, and torsion.

Opening the Section Library

Click the Sections button in the ribbon, or click the book icon next to the Section field in the Properties panel when a member is selected.

Section Library

The built-in library includes sections organised by region:

  • Australia - Steel, cold-formed steel, aluminium, and timber
  • Brazil - Steel
  • Canada - Steel, cold-formed steel, and timber
  • Europe - Steel and timber
  • India - Steel and cold-formed steel
  • Japan - Steel
  • United Kingdom - Steel and timber
  • United States - Steel, cold-formed steel, and timber

Section Properties

Each section requires these geometric properties for analysis:

  • Area (A) - Cross-sectional area, affects axial stiffness
  • Moment of Inertia (Iyy, Izz) - Resistance to bending about each axis
  • Torsional Constant (J) - Resistance to twisting

Design-axis convention: steel design checks treat Izz and Szz as the major/strong-axis properties, and Iyy and Syy as the minor/weak-axis properties. For Eurocode 3 output this is reported using EC3 notation, where the strong axis is y-y. If you import or create a custom section with these axes swapped, bending, buckling, and LTB checks may be assigned to the wrong design axis.

Adding Sections

Ways to add sections to your model:

  • From Library - Browse standard sections organised by region and select to add to your model
  • Parametric custom - Click Create Custom in the library to define a common shape with your own dimensions (sign-in required)
  • Drawn custom - Create arbitrary geometry in the Custom Section Builder, save it (Pro), then pick it from the section library in Structural FEA

Parametric Custom Sections

For standard profile families, use Create Custom in the Section Library. You choose a shape type and enter dimensions; section properties are calculated automatically. This form is limited to common shapes:

  • I-Shape - Universal beam profile
  • Channel - C-section profile
  • Tee - T-section profile
  • Angle - L-section profile
  • Solid Rectangle - Rectangular bar
  • Solid Circle - Round bar
  • Circular Hollow - Pipe / CHS
  • Rectangular Hollow - RHS / SHS

If your cross-section is not one of these families (built-up members, openings, freeform outlines, or profiles imported from CAD), use the Custom Section Builder instead.

Drawn Custom Sections (Custom Section Builder)

The Custom Section Builder is a separate tool for arbitrary cross-sections that the parametric form cannot represent.

Use it when you need to:

  • Draw freeform outlines - Point or line drawing for solid and thin-walled shapes
  • Build up multiple shapes - Join parts into one connected section
  • Add holes and openings - Circular or freeform voids in the profile
  • Start from a library section - Load a standard section and edit it
  • Import DXF - Bring in a closed 2D section outline from CAD

Properties (area, centroid, bending, torsion, shear, and warping) are calculated from a finite element mesh of the outline. Pro users can also review section stress contours and export a PDF report.

Using drawn sections in Structural FEA: Pro users can Save a calculated section to the cloud. Saved drawn sections then appear in the Structural FEA section library and can be assigned to members like any other section for structural analysis.

Limitations: Drawn sections support analysis only. They cannot be used for member design code checks. The section must be a single homogeneous material (not multi-material composite construction). Recalculate and re-save after editing before assigning the section in FEA.

Full workflow details (drawing tools, DXF import, calculate limits, and saving) are in the Custom Section Builder documentation.

Assigning Sections

  1. Select one or more members
  2. In the Properties panel, click the Section dropdown
  3. Select the desired section

All selected members will be updated to use the chosen section.

Section Colours

Each section has an assigned colour for visualisation. Click the colour swatch in the Section Library to change it using the colour picker or preset palette. Members are displayed in their section's colour unless selected.

3D Rendering

Switch to "Rendered" view mode (in the Display panel) to see members displayed with their actual cross-section shape extruded along the member length. This helps verify section assignments visually.