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Plate (Geometry)

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

Plane plate propertyDescription
Modules where available1584964861773-839.png  1584964937253-799.png
Reference plane positionHorizontal in 1584964863812-737.png
 Arbitrary (horizontal, vertical and skew) in 1584964939673-862.png
GeometryAny shape
ThicknessConstant or variable
EccentricityOnly for display
Edge connectionRigid, hinged, elastic (spring) linear or non-linear
MaterialSteel, concrete, timber and general
Orthotropic featureAvailable
Load directionVertical in 1584964866388-702.png
 Arbitrary in 1584964943247-379.png
Load typeAll point, line and surface load
Available analysis resultsDisplacement, internal forces, stresses, stability and vibration shape in 1584964870610-774.png  1584964945063-876.png
Available designRC design in 1584964868831-518.png  1584964946774-926.png
 Timber design in 1584964948250-699.png
Default Short CommandPL

Table: Plate properties

Definition steps

  1. If needed (and available in the current FEM-Design module), set a proper position for the working plane.
  2. Start 1584964968056-114.png  Plane plate command from 1584964974923-837.png  tabmenu and choose 1584964984063-630.png  Define.
  3. Set the properties of the new plate at 1584965014354-973.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).
    • Alignment and Eccentricity (General)
      With alignment the position of the reference (definition) plane can be set to top, center or bottom.
      Eccentricity (e) adds “virtual” distance between the reference plane and the calculation (middle!) plane if “Consider eccentricity in calculation” option is unchecked, otherwise the eccentricity has effects in the calculation. This option is useful for displaying regions with different thickness values.
      warning.pngAlignment and eccentricity have no effect in calculations if “Consider eccentricity in calculation is checked off. They are only to display plate “solid” with its defined position.

      Eccentricity value can be displayed in model view (Display settings).
      The “Consider eccentricity caused by cracking in cracked section analysis” option is for Reinforced concrete slabs. With this option modeling the eccentricity changes after cracking is available. The following figure shows the eccentricity changes.
      Figure: Explaining cracked and uncracked analysis

    • Thickness (General)
      By default, only plate with constant thickness (t1=t2=t3) can be set at Default settings. Use the Variable thickness tool to define different t values that declare the top/bottom surface as a linearly variable plane.
    • Orthotropic features (General)
      The ratio between the E1 and E2 elasticity modules in the main directions can be set here. So, if the value is 1, the new plate will be isotropic, otherwise it is orthotropic. The orthotropy direction can be set with the angle between E1 direction and the plate’s local x’ axis (Alpha).
      warning.pngIn 1584964882760-930.png  Plate module the local x’ axis is always parallel with the global X axis.
    • Material
      Any type of materials can be set for plate Analysis, but design can be run for concrete only. The applied material name can be displayed in model view (Display settings).

  4. Set the default connections for all plate edges to rigid or hinged with the tool palette’s Edges option.
    Figure: Default edge connections
    light.pngUse the Edge connection tool to modify the default connections by the selected edges of a predefined plate. Hinged, rigid, semi-rigid (spring), free connections can be set with linear and non-linear behavior.

    The edge connections can be calculated as plastic behavior, which shows the figure below. The values can be customized.

  5. Choose a geometry definition method for the plate reference plane (set by Alignment and Eccentricity).

  6. Define the plate region in the model view based on the chosen geometry method. In 1584964892355-404.png  module the slab plane can be horizontal only, while in 3D modules any skew position can be set. All region definition points have to be in the same plane. UCS may help to find the requested position of the new plate region.
    Figure: Different working planes for plate definition

Optional steps:

  1. Modify default thickness (Variable thickness)
    Constant slab thickness can be fast modified with the 1584965407799-477.png Properties tool. Just select the plate(s) and set a new value under General Tab.
    Constant thickness can be changed to variable, or reverse, with the 1584965422960-686.png Variable thickness tool.
    Steps of defining plate with variable thickness:
    1. Inactivate the 1584965444666-926.png  link buttons to allow giving different values in the t fields.
    2. Type the t1, t2 and t3 according to the current length unit.
    3. Select the plate you would like to modify.
    4. Define three points in the plane of the selected plate’s reference plane, where t1, t2 and t3 will be measured. The measurement of the thickness values depends on the position of the reference plane (Alignment and Eccentricity).
      Figure: Align the thickness of the middle slab to its neighbors

      Figure: Align circular slab thickness to a variable height wall
      warning.pngThe measurement of the thickness values depends on the position of the reference plane (Alignment and Eccentricity).


      light.pngYou are allowed to place the measuring points outside the region, too.
  2. Modify the default edge connections with 1584965607228-963.png . Just select the plane and then its edge(s) to set connection conditions, and finally set the requested motion and rotation settings.
    Figure: Modification of two slab edges

    Motion-Rotation / Compression-Tension
    The x’, y’ and z’ are valid in the connection’s local system displayed in the preview and as a symbol in the middle of the edges in the model view. Choose “Rigid” or “Free” from the drop-down lists, or type stiffness values (spring connection).
    light.pngActive 1584965667943-189.png  link button assigns the stiffness value typed in the Compression field to the Tension field. Inactive icon 1584965673355-713.png  lets to define stiffness values separately.

    Predefined types
    Click 1584965881918-428.png  to set all motion and rotation components to “rigid”. The result will be a “totally rigid” connection.
    Click 1584965887463-975.png  to set all motion components to “rigid” and all rotation components to free (allow rotation around all directions). The result will be a hinged connection.
    Click 1584965892975-192.png  to set all components to free. This tool gives the possibility to virtually connect independently moving elements.
    Figure: Edge connection types and their displacement effect

    Click 1584965861079-430.png  to assign the stiffness value defined in the Compression field to the Tension field by components.
    Click 1584965866292-309.png  not to allow tension for all connection components.
    Click 1584965872196-134.png  not to allow compression for all connection components.

    Setup “Rigid”
    With this option the value of “infinite” rigidity can be defined by motion and/or rotation for selected connections.
    For all edge connections, the value of “infinite” rigidity can be defined and set as project default at Settings > Calculation> “Rigid” values > Connections.

    light.pngAs a real example, Edge connection gives the possibility to model prefab concrete elements too. Define the objects with the Plate/3D plate commands, set the thickness value of the regions to substitute the real cross-section with the holes, and finally add “hinged” edge connection (C= 0) to one of the region at the common edge with the other one (see the next figure).

    Figure: Modeling slab elements connected to each other (hollow-core prefab slabs)

  3. Add hole with 1584965799489-841.png  tool.
    In 3D modules, select a plate region and define hole in it or cut it by using a geometry mode. Selecting a plate displays the UCS in the reference plane of the plate.
    Figure: Hole and cuttings

    In 1584964910480-366.png  Plate module, just define hole or cutting by using a geometry mode in the required plate reference plane. Selection of the host plate is needed, if the hole region intersects more than one regions.
  4. Modify the reference plane geometry with the Edit menu commands valid for region elements.
  5. Modify the plate properties with the 1584965943457-695.png  Properties tool of the Plate tool palette.
  6. Information (the volume of the plate solid and the position of its centre of gravity) about a selected plate can be inquired with the 1584965948512-470.png  Info tool. A drawing point can be placed in the plate’s centre of gravity, if needed.
  7. Set the display settings of plates at Settings > All > Display > Shell.
  8. The plates are stored on “Plates” Object layers. At layer settings, the default color and pen width can be set for all plate regions. The color and pen width settings by selected plate elements can be modified by Edit > Properties > Change appearance.
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