Plate (Geometry)

Plane plate property	Description
Icon
Modules where available
Reference plane position	Horizontal in
	Arbitrary (horizontal, vertical and skew) in
Geometry	Any shape
Thickness	Constant or variable
Hole	Available
Eccentricity	Only for display
Edge connection	Rigid, hinged, elastic (spring) linear or non-linear
Material	Steel, concrete, timber and general
Orthotropic feature	Available
Load direction	Vertical in
	Arbitrary in
Load type	All point, line and surface load
Available analysis results	Displacement, internal forces, stresses, stability and vibration shape in
Available design	RC design in
	Timber design in
Default Short Command	PL

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  Plane plate command from  tabmenu and choose  Define.
   

3. Set the properties of the new plate at 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.

     Alignment 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).

     In  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

   Use 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   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:

7. Modify default thickness (Variable thickness)
   Constant slab thickness can be fast modified with the 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  Variable thickness tool.
   Steps of defining plate with variable thickness:
   1. Inactivate the   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

      The measurement of the thickness values depends on the position of the reference plane (Alignment and Eccentricity).

      
       

      You are allowed to place the measuring points outside the region, too.

8. Modify the default edge connections with  . 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).

   Active   link button assigns the stiffness value typed in the Compression field to the Tension field. Inactive icon   lets to define stiffness values separately.

   Predefined types
   Click   to set all motion and rotation components to “rigid”. The result will be a “totally rigid” connection.
   Click   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   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
   
   Behavior
   Click   to assign the stiffness value defined in the Compression field to the Tension field by components.
   Click   not to allow tension for all connection components.
   Click   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.

   As 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 (Cx = 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)

9. Add hole with   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  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.
10. Modify the reference plane geometry with the Edit menu commands valid for region elements.
11. Modify the plate properties with the  Properties tool of the Plate tool palette.
12. Information (the volume of the plate solid and the position of its centre of gravity) about a selected plate can be inquired with the  Info tool. A drawing point can be placed in the plate’s centre of gravity, if needed.
13. Set the display settings of plates at Settings > All > Display > Shell.
    
14. 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.