# Fictitious bar (Geometry)

Contents
 Fictitious bar property Description Icon Modules where available Function Bar elements with given stiffness values Axis position Horizontal in Arbitrary (horizontal, vertical and skew) in Geometry Straight and curved End connection Rigid and hinged, or custom defined by Point-point connection Stiffness Editable (but, material and cross-section definition is not available) Load direction Vertical in Arbitrary in Load type All point and line load Available analysis results Displacement and internal forces Default Short Command FICB

Table: Fictitious bar properties

Figure: Fictitious bars connect plate elements

 The program automatically generates “rigid” fictitious bars in the end points of “bars” modeled as a shell model (end edges of shell regions; see Shell model).

Definition steps

1. If needed (and available in the current FEM-Design module), set a proper position for the working plane.
2. Start  Fictitious bar command from tabmenu and choose Define.

3. Set the properties of the new bar at  Default settings:
• Stiffness (General)
EA, GIt, EI1 and EI2 stiffness values can be assigned to bars. No definition of material and cross-section is needed. The local y’ axis represents the 1st principal axis, and the local z’ axis defines the 2nd principal axis.
The value of rigid stiffness (“infinite” rigidity) can be defined and set as project default at Settings > Calculation> “Rigid” values > Fictitious bar.
• Connections
In  , the end connections are fully rigid.
In 3D modules, the end connections can be set under the Connections tab similarly to Beams. Only the released motion (arrow) and rotation (two-headed arrow) components are displayed in the model view (Display settings).
4. Define the direction of the cross-section 1st principal axis (local y’ axis; only in 3D modules).
The y’ axis cannot be modified in the  module, so it is always parallel with the Global X-Y (working).
5. Choose a geometry definition method for the bar reference line (axis).
6. Define the bar in the model view based on the chosen geometry method.

Optional steps:

1. Modify the geometry with the Edit menu commands valid for line elements.
2. Modify the bar properties with the Properties tool of the Fictitious bar tool palette.
3. The fictitious bars are stored on “Modeling tools” Object layers. At layer settings, the default color and pen width can be set for all fictitious bars.