Truss [TB]

A truss element is a straight member (chord, diagonal, or vertical) framing between two Insertion Points. The element is assigned a cross section and end-release conditions, and can be modeled analytically as a pure truss (axial only) or as a beam element depending on the selected FE type.

General

Insertion Points: Two Insertion Points defining the start and end of the truss member. The insertion points must be picked from previously defined objects and drive the overall geometry of the member in 3D and in the FE model.

Section: Cross section assigned to the truss member. Use a section previously defined under Properties > Sections or import a new one. The section controls both the 3D view and the stiffness/strength properties used by FEA.

Orientation Angle: Rotation of the cross section about its local longitudinal axis. Use this to orient asymmetric sections (e.g., channels, angles) correctly relative to the member line.

Vertical Offset (point-1): Vertical offset applied at the start end (point 1). Positive values shift the start of the member upward relative to the Insertion Point.

Vertical Offset (point-2): Vertical offset applied at the end (point 2). Positive values shift the end of the member upward.

Horizontal Offset (point-1): Transverse (horizontal) offset of the start end from the Insertion Point. Positive values shift point 1 to the right when looking upstation.

Horizontal Offset (point-2): Transverse (horizontal) offset of the end from the Insertion Point. Positive values shift point 2 to the right when looking upstation.

Longitudinal Offset (point-1): Longitudinal (along-alignment) offset applied at the start end. Positive values move point 1 upstation.

Longitudinal Offset (point-2): Longitudinal (along-alignment) offset applied at the end. Positive values move point 2 upstation.

Local Axial Offset (point-1): Offset applied at the start end along the member's local axial direction. Use for rigid offsets between the member's working point and the node location.

Local Axial Offset (point-2): Offset applied at the end along the member's local axial direction. Use for rigid offsets between the member's working point and the node location.

Bolt

Bolt Arrangement (point-1): Layout of bolts at the start-end connection. Used by gusset-plate computations and refined analysis to determine bolt positions relative to the truss member.

Bolt Arrangement (point-2): Layout of bolts at the end connection. Same role as at point 1, for the other end of the member.

Overrides

Type [Truss/Beam]: Selects the FE element type. Truss models the member with axial stiffness only (no bending). Beam models the member as a frame element with full bending, shear and torsion stiffness. Choose based on the actual connection behavior (pinned joints vs. moment-resisting).

Modulus of Elasticity Factor: Multiplier applied to the section material's modulus of elasticity in FEA. Default 1.0 uses the unmodified material value; lower values soften the member.

Poissons's Ratio Factor: Multiplier applied to Poisson's ratio. Default 1.0.

Section Area Factor: Multiplier on the section area used by FEA. Default 1.0. Use to reduce the effective axial stiffness without changing geometry.

Section Shear Area Y Factor: Multiplier on the section shear area in the local Y direction. Default 1.0.

Section Shear Area Z Factor: Multiplier on the section shear area in the local Z direction. Default 1.0.

Section Torsion Constant Factor: Multiplier on the section torsion constant J. Default 1.0. Relevant only for Beam type.

Section Inertia Y Factor: Multiplier on the section moment of inertia about local Y. Default 1.0. Relevant only for Beam type.

Section Inertia Z Factor: Multiplier on the section moment of inertia about local Z. Default 1.0. Relevant only for Beam type.

EndRelease

Node-1 Tx [Free/Fixed]: Translational end condition at the start node along the member's local X axis. Fixed transfers axial force; Free releases it.

Node-1 Ty [Free/Fixed]: Translational end condition at the start node along local Y.

Node-1 Tz [Free/Fixed]: Translational end condition at the start node along local Z.

Node-1 Rx [Free/Fixed]: Rotational end condition at the start node about local X (torsion). Fixed transfers torsion; Free releases it.

Node-1 Ry [Free/Fixed]: Rotational end condition at the start node about local Y (bending).

Node-1 Rz [Free/Fixed]: Rotational end condition at the start node about local Z (bending).

Node-2 Tx [Free/Fixed]: Translational end condition at the end node along local X.

Node-2 Ty [Free/Fixed]: Translational end condition at the end node along local Y.

Node-2 Tz [Free/Fixed]: Translational end condition at the end node along local Z.

Node-2 Rx [Free/Fixed]: Rotational end condition at the end node about local X.

Node-2 Ry [Free/Fixed]: Rotational end condition at the end node about local Y.

Node-2 Rz [Free/Fixed]: Rotational end condition at the end node about local Z.

Use Local Release [Yes/No]: When Yes, the end-release directions above are interpreted in the member's local axis system; when No, they are interpreted in the global axis system.

Refined Analysis

Plane Thickness For Refined Analysis: Thickness of the planar region used when the member participates in a refined shell-based analysis (e.g., at gusset-plate connections). Used to determine the effective section for the local solid/shell model.

Plane Offset For Refined Analysis: Offset between the member center line and the refined-analysis plane. Used when the connecting plate lies off the member axis.

3D Detailing

Truss Opacity: Opacity of the truss member in the 3D view. Values from 0 (fully transparent) to 1 (fully opaque). Does not affect FEA.

Show Bolt/Holes (Detailing) [No/Yes]: Toggles the rendering of bolt holes and bolts defined in the Bolt group. 3D visualization only.

Start Face Skew Angle (X-Axis): Rotation of the start face of the 3D representation about the member's local X axis. 3D visualization only.

End Face Skew Angle (X-Axis): Rotation of the end face of the 3D representation about the member's local X axis. 3D visualization only.

Start Face Skew Angle (Y-Axis): Rotation of the start face of the 3D representation about the local Y axis. 3D visualization only.

End Face Skew Angle (Y-Axis): Rotation of the end face of the 3D representation about the local Y axis. 3D visualization only.