Members

Member Properties

Select a member to view and edit its properties in the Properties panel:

Section

The cross-sectional shape determines structural behaviour. Select from the dropdown or click the book icon to open the Section Library.

Material

The material defines stiffness (Young's Modulus) and density for self-weight. Select from the dropdown or click the book icon to open the Material Library.

End Releases (Member Fixity)

Control how the member connects at each end. The Properties panel shows Node A (start) and Node B (end) fixity controls with preset options:

• Fixed (FFFFFF) - Fully rigid connection (default)
• Pinned Rz (FFFFFR) - Major-axis rotation released
• Pinned Ry, Rz (FFFFRR) - Both bending rotations released
• Pinned All (FFFRRR) - Torsion and both bending rotations released

The 6-character code represents: Dx, Dy, Dz, Rx, Ry, Rz (F = Fixed, R = Released). The code is read in the member's local frame; on a sideways member the releases follow the 90° section roll (see Sideways below).

Ry and Rz releases act about the section's principal axes. For sections with nonzero Alpha, such as single angles and Z-sections, these differ from the geometric axes shown by Member Local Frame and used for authored Local loads. Releasing one bending rotation makes the corresponding principal-axis end moment zero; a moment component about a geometric axis can remain. Releasing both Ry and Rz (FFFFRR) gives a bending-moment-free end.

Member Type (Tension/Compression Only)

Members can be set to carry only tension or only compression. This is useful for modelling diagonal cross-bracing where only the tension diagonal is engaged under each load direction (tension-only), or struts that buckle out of action under reversed load (compression-only). Set the Type field in the Properties panel to Normal, Tension, or Compression.

Sideways (Section Rotation)

The Sideways toggle rotates the cross-section 90° about the member's longitudinal axis. This is useful when you need to orient an I-beam with its web horizontal (e.g., for a lintel or spandrel beam). Toggle it in the Properties panel when a member is selected.

Because the section is genuinely rolled, everything defined in the member's local frame follows the roll: Local-axis point and distributed loads, thermal gradients, end releases, and the transverse components of a Local end-eccentricity offset all rotate 90° with the section so they keep acting on the cross-section as drawn: a Local Y load, a release about local y, or a top-of-section eccentricity follows the rolled section, and the on-canvas glyphs roll to match. Global-axis loads and Global eccentricity offsets are unaffected.

End Eccentricity

The Eccentricity section in the Properties panel lets you offset the structural endpoints of a member from the joint nodes you drew. This mirrors the “Member Eccentricity” / “Insertion Point” / “Joint Offsets” feature found in other FEA tools, and produces a true textbook M = N · e moment from any axial force.

For each end (A and B) you can enter an offset vector with x, y and z components in the active length unit. Choose between two reference axes:

• Local axes (default): interpreted in the member's own coordinate frame: x along the member from A to B, y and z the two transverse directions. On a sideways member the transverse y / z follow the section's 90° roll, so a top-of-section offset stays on the rolled top. Use this when the offset is described relative to the member (e.g. “0.3 m along the beam to clear the column face”).
• Global axes: straight global X / Y / Z. Use this when the offset is defined by surrounding geometry (e.g. “this brace's structural line sits 0.3 m below the top chord”).

The 3D viewer shows a thin dashed line from each joint to its offset endpoint and an ECC chip at the member midpoint so you can see at a glance where the structural line actually runs. Member force diagrams, the deflected shape, and member loads all ride along the offset line, and design-check member lengths use the offset-adjusted length too.

Clearing every axis of the offset (or typing 0 in each box) removes the eccentricity entirely and the member reverts to bit-identical behaviour with a non-eccentric beam.

Loads

When a member is selected, the Properties panel provides a Loads section with quick-access buttons to open the load dialogs for the selected member. You can apply node loads to either end, or distributed/concentrated loads along the member length.