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SkyCiv Structural 3D

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  4. Plates


Plates are the two-dimensional elements of a structure. Most commonly they are used to model slabs, walls, and decks under applied loads.

SkyCiv has powerful meshing and plate analysis capabilities, to help engineers 2D plates such as slabs and retaining walls. Plates can be defined as any material, and after solving, the user is able to get the internal forces, pressures, and deflection of this shell element. These results can be displayed in the graphical interface, exported as CSV results, or in PDF format via our analysis reports.


Click here for more information on SkyCiv Plate Analysis Results

Creating Plates

Plates can be created (and edited) via the form, the datasheet, or by using mouse controls. To use mouse controls, ensure you are in the plates menu. Click the nodes – without dragging – that form the plate. Click the last node a second time to end the plate.

To specify a plate in SkyCiv Structural 3D simply provide values for:

  • Node IDs – The nodes which make up the plate. Specified by the node numbers separated by commas.
  • Plate Thickness – The thickness of the plate. For thick Mindlin plates, it is recommended that the plate area to thickness ratio is below 8.
  • Material ID – The ID used to identify the material of the plate.

Advanced Settings

The Advanced Settings for plates can be viewed by activating its toggle switch. Advanced form fields have blue labels, and include options for:

  • Rotation Z – The rotation (in degrees) of the plate about its normal axis (it’s local Z-axis).
  • Plate Type – The type of plate element. Mindlin plates are the recommended default. They take into account shear deformations which is appropriate for thick plates and is based on Mindlin-Reissner Theory. Kirchhoff plates do not consider shear deformations which are suitable for thin plates.
  • Offset – Offset the plate perpendicular to its plane. Similar to member offsets, the plate is connected to the node locations using rigid links.
  • Plane State – Choose whether to calculate Plane Stress or Plane Strain during the analysis of your plate

As a plate is created, it will appear as a shaded region with a label. Plates are identified by their plate number which appears in the middle of the plate by default. Users can click and move the plate number label if they wish.

Troubleshooting Models with Multiple Plates

Sometimes with larger structures (or structures with multiple plates) may fail to solve due to improper connectivity during the meshing phase. We highly recommend meshing all your plates at once to avoid issues like this.

If your structure has multiple plates and is failing to solve, we recommend re-meshing the structure all at once. The easiest way to do this is to:

  1. Select all (CTRL + A) and Click Advanced – Plates – Plate Mesher
  2. Click Unmesh to unmesh all your existing plates
  3. Select all the plates again (CTRL + A) and go back into the Mesher (Advanced – Plates – Plate Mesher)
  4. Then select Unstructured Quadrilaterals
  5. Click Mesh

The software will then mesh all your plates in one go – ensuring proper connectivity throughout your model. This is the most reliable method as it ensures adjacent plates are connected with common nodes.


In this example, we will create a plate and apply some supports.

1) Plot the four nodes (0,0,0) , (1,0,0) , (1,1,0) and (0,1,0).

2) The plate can be created in 4 different ways to make it quick and easy, based on your preferred method of input. Let’s look at each one.

1. Using the Left Menu:

Firstly, plates can be created in a form by clicking the ‘Plates’ menu button on the left navigation bar. Specify 1,2,3,4 as the order of the plate nodes in the ‘Node IDs’ field. Click Apply.

2. Right Click:

Highlight the nodes that will bound your plate, then right click – Add Plate. The software will automatically put the nodes into clockwise direction and apply a plate. Highlighting the nodes is easy with CTRL + Click drag (in two directions) or CTRL + A to select all nodes:

3. Using the Datasheet

Thirdly, plates can be created by clicking into the Plates Datasheet. This method is similar to the first, except in tabular format. It allows you to view or create many plates at once. Specify 1,2,3,4 in the ‘Nodes’ column and click apply to create a plate. Note, when specifying nodes in the table, order the nodes as they appear around the plate. i.e. go in a clockwise or counter-clockwise order to create a “string” of nodes that make up the plate.

4. Click Between Nodes:

Lastly, plates can be created by using mouse controls. To use mouse controls, ensure you are in the Plates menu. Click the nodes – without dragging – that form the plate. Click the last node a second time to end the plate.

3) Apply 4 supports by clicking the ‘Supports’ menu button, and enter in 1,2,3,4 in the ‘Node ID’ field.

Here is what the plate should look like:

 Now you have the plate created, check out the next article to follow this example and learn how to mesh your plate.


Orthotropic Plates

Orthotropic plates can also be added in SkyCiv Structural 3D. To add orthotopic plates. First start by adding an orthotopic material (with Ex, Ey, Gxy, Gxz, Gyz) under the Materials menu:

Adding Orthotropic Plates in SkyCiv Structural 3D
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