0 Votes

Truss member (Geometry)

Last modified by Iwona Budny Bjergø on 2022/01/18 12:24

Truss member propertyDescription
Modules where available1584962049985-838.png  1584962112943-724.png 
FunctionIt models bars with limited compression and tension-only bars like cables, pull rods, diagonal braces etc.
Axis positionArbitrary (horizontal, vertical and skew)
Cross-sectionArbitrary profile
  • Always hinged (cannot be modified)
  • It can be connected to other elements only at its ends
  • It does not intersect other elements cross it visually
MaterialSteel, concrete, timber and general
Load directionAxial
Load type
  • Dead load (will be distributed to the end nodes)
  • Uniform line temperature variation
  • Shrinkage
  • Line stress load
  • Point mass (will be distributed to the end nodes)

Displacement, normal force and stress

Available designSteel design in 1584962052868-342.png  1584962107334-338.png
 RC design in 1584962054171-497.png  1584962108670-105.png
 Timber design in 1584962056066-559.png  1584962110276-660.png

Steel truss member can be modeled/designed as the set of shells (Shell model)

Default Short CommandTR

Table: Truss member properties


Figure: Modeling a truss

Definition steps

  1. If needed (and available in the current FEM-Design module), set a proper position for the working plane. In the 3D design modules, respect that the gravity direction is always the Global Z axis direction.
  2. Start 1584962145873-183.png  Truss member command from 1584962153291-475.png  tabmenu and choose 1584962163902-770.png  Define.
  3. Set the properties of the new truss element at 1584962192903-457.png  Default settings:1584962206496-409.png
    • Identifier (General)
      The program automatically generates it, but you can define custom value. Identifier (ID and Position) number can be displayed in model view (Display settings).
    • Non-linear behaviour (General)
      Limited capacity and Brittle/Plastic can be set for both compression and tension. These options are considered only for load combinations calculated as non-linear elastic. Plastic behaviour is only considered for load combinations calculated as non-linear elastic + plastic.
    • Section
      Choose a profile from the Section library or define a new cross-section by parameters. The applied section name can be displayed in model view (Display settings).
    • Material
      Any type of materials can be set for beam Analysis, but design can be run for concrete, steel and timber elements only. The applied material name can be displayed in model view (Display settings).
  4. Define the direction of the cross-section y’ axis.
  5. Choose a geometry definition method for the truss element reference line (axis).
  6. Define the element in the model view based on the chosen geometry method.

Optional steps:

  1. Modify the bar properties with the 1584962257256-961.png  Properties tool of the Truss member tool palette.
  2. Set the display settings of truss elements at Settings > All > Display > Beam, Column and Truss similarly to Beams.
  3. The truss elements are stored on “Truss members” Object layers. At layer settings, the default color and pen width can be set for all truss elements. The color and pen width settings by selected truss elements can be modified by Edit > Properties > Change appearance.