0 Votes

Beam (Geometry)

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

Beam propertyDescription
Modules where available1584954727417-623.png  1584954772523-273.png  1584954826854-710.png  
Axis positionHorizontal in 1584954729966-714.png
 Arbitrary (horizontal, vertical and skew) in 1584954775016-637.png   1584954837091-904.png
GeometryStraight and curved
Cross-sectionArbitrary profile
End connectionArbitrary
MaterialSteel, concrete, timber and general
Load directionVertical in 1584954734538-159.png
 Arbitrary in 1584954777721-134.png   
Load typeAll point and line load
Available analysis resultsDisplacement, internal forces, stresses, stability and vibration shape in 1584954743884-636.png  1584954780053-908.png  1584954848454-996.png
Available designSteel design in 1584954737815-513.png  1584954782074-243.png  1584954851454-924.png
 RC design in 1584954739744-425.png  1584954783463-317.png  1584954812836-543.png
 Timber design in 1584954741734-429.png  1584954784586-765.png  1584954809763-917.png
AlternativeSteel beam can be modeled/designed as the set of shells (Shell model)
Default Short CommandBM

Table: Beam properties

light.pngTypical 2D and 3D frame structures build by beams (only) can be fast defined with the so-called Parametric model tool. Fast means, that in a dialog you can set the beam sizes and positions by parameters. Besides the geometry, Wizard adds loads and supports to the beam-system.

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 1584954864239-773.png  Beam command from 1584954869936-643.png  tabmenu and choose 1584954919929-654.png  Define.
  3. Set the properties of the new beam at 1584954949735-668.png Default settings:* 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).

    • Camber simulation by prestressing (General)
      To simulate camber of the elements check the box next to Camber simulation by prestressing in the General tab.

      To calculate camber a camber-type load case needs to be defined. The effect is calculated as a kinematic load.
      warning.pngCamber calculation gives statically correct result only for non-eccentric, hinged beams and shells. This only corrects the displacement result and no internal forces will rise in the model.
    • Section
      Choose a beam 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).

    • End conditions
      In 1584954754120-657.png , the end connections are fully rigid.
      In 3D modules, the end connections can be set under the End conditions tab. Only the released motion (arrow) and rotation (two-headed arrow) components are displayed in the model view (Display settings). End connections can be fully customised for bar ends by setting the rigidity of the displacement components.
      The component directions are valid in the beam’s local co-ordinate system.
      Inactive component means a fixed motion/rotation, while a checked component behaves according to the user-specified rigidity value.

      With the „Rigid” and the „Hinged” buttons pre-defined end condition values can be applyed to the bar ends.
      The local x’ axis always points the beam end, so the start and end point position can be followed from the beam’s local co-ordinate system.

      Only the released motion (arrow) and rotation (two-headed arrow) components are displayed in the model view (Display settings).
      The connection settings is not available in 1584954757118-166.png , the end connections are always fully rigid.
      Eccentricity in analytical model (End conditions)
      Eccentricity has effect in calculation. The default position (center of gravity) of the beam axis (local x’ axis) can be set in the aspect of analysis/design calculation.
      The axis position (symbolized with yellow point in the section) can be set with its coordinates in the local y’z’ plane, or can be placed into special section points (e.g. plate corners) by dragging the yellow point into the requested position.
      Two type of eccentricity option can be chosen:
      First type (“End releases applied at the ends of the theoretical axis”) is typically used for modeling RC bars which work together with concrete slabs (slab normal forces transfers to the bar).
      Figure: Modeling of a “ribbed concrete slab”

      The second type (“End releases applied at the ends of the gravity (physical axis)”) is for modeling single plate and bars which are not working together.

      Figure: Modeling of a steel beam under slab in 3D Structure module

    • Physical model
      Eccentricity of the physical model can be set in the Physical model tab, in a similar way as the Eccentricity of analytical model. It has no effect on the calculation.

    • Material
      Any type of materials can be set for beam Analysis, but design can be run for concrete, steel and timber beams only. The applied material name can be displayed in model view (Display settings).

  4. Define the direction of the cross-section y’ axis (only in 3D modules).
    The y’ axis cannot be modified in the 1584954762112-163.png  module, so it is always parallel with the Global X-Y (working).
  5. Choose a geometry definition method for the beam reference line (axis).
  6. Define the beam 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 1584955305201-229.png  Properties tool of the Beam tool palette.
  3. Set the display settings of beams at Settings > All > Display > Beam, Column and Truss.
  4. The beams are stored on “Beams” Object layers. At layer settings, the default color and pen width can be set for all beams. The color and pen width settings by selected beam elements can be modified by Edit > Properties > Change appearance.
Copyright 2023 StruSoft AB
FEM-Design Wiki