Create a parametric profile by sketching (closed profile example)

Question:
How can I create a closed parametric profile with variable angles using the Sketch Editor?

Answer:
The following support article will take you through step by step instructions for creating a parametric profile using the Sketch Editor. In this example a parametric rectangular hollow section will be created using the Sketch Editor. The finished profile is shown below. The overall height, overall width, height of top flange, height of bottom flange and web thickness can be varied for this example profile.

See also: Create parametric profiles by sketching
 

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Example

1. Open Sketch Editor

Set up a grid

The Sketch Editor uses the same grids that appear in the Tekla Structures model views. In this example we will hide the existing grid then create a grid that will help us draw the outline of the shape. After the profile outline has been sketched we will switch off grid display.

1. Click on one of the grid lines to select it, then right-click and select Hide

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2. From the Tekla Structures Edit tab, select Grid > Create grid

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3. Enter the values shown in the X and Y coordinates below and click Create.

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The Z coordinates will not be used so there is no need to change these.

Sketch the outline of the profile

Zoom in on the grid as shown below. You will need to create two closed polylines: one for the outer boundary and one for the inner boundary.

1. Click the Sketch polyline button
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2. Click points 1,2,3,4,1 and click middle mouse button to complete the first polyline
3. Click points 5,6,7,8,5 and click middle mouse button to complete the second polyline

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Hide the grid

1. Double-click somewhere on the background inside the Sketch Editor to bring up the View Properties window
2. Click Display... button
3. Untick Grids and click Modify

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Save the sketch

1. Click the Save sketch button  
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2. Enter a name for the sketched profile into the Prefix field and click OK.

The name must be all uppercase and contain all letters.
 

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Using the profile in the model

1. After saving the sketch, close the Sketch Editor by clicking the cross in the top right corner of the Sketch Editor window
2. Create a beam or column in the model then double-click it to open its Properties
3. Click the Profile: Select... button, the Select Profile dialog opens
4. Type the name of the section into the Filter: field and click the Filter button
5. Click the + sign to expand the selection tree and select the section
6. Click Apply and then OK

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7. Click Modify in the part Properties dialog box to change the profile.

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Modify the sketch

1. Open the Profile catalog, File > Catalogs > Profile catalog

Note: You cannot modify profiles when opening the profile catalog via the Select... button in the part properties dialog box.

2. Search for the profile in the Profile catalog
3. Right-click on the profile and select Edit profile. This will open the profile in the Sketch Editor

Add a horizontal and vertical dimension

1. Hide the grid if it is showing, select grid, right-click and select Hide
2. Click the Sketch horizontal dimension button  
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3. Create a dimension across the top of the profile
4. Click the top left corner of the outer polyline followed by the top right corner and then click somewhere above the profile to place the dimension line

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Tip: If you want to be able to click anywhere in the background, make sure the Snap to any position button 

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 is selected. You can toggle this on and off using the F7 key or if a modelling command is active, you can right-click and select Free from the context menu.
 

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5. Click the Display variables button 
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    to open the Variables dialog box

When you create a dimension, a variable is created as shown below. Change the value of the variable by selecting the Formula cell, typing a larger number and pressing the Return key. The width of the profile will increase to this value.
 

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6. Using the Sketch vertical dimension button 
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    create a vertical dimension from the bottom left to the top right of the profile. Test it is working by changing its value in the Variables dialog box.

Tip: It can be easy to make mistakes when using the sketch editor for the first time so it is recommended that you regularly save the sketch by clicking the Save sketch button.

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This way if you make a mistake you can easily go back to the last working version.

Create a user input variable

1. In the Variables dialog box, click Add

A new variable is added. This variable will be used to hold the value entered by the user for the total width of the profile.

2. Rename the variable ui_b. For clarity we distinguish input variables from other variables by prefixing them with ui_, which stands for 'user input'
3. Rename the Label in dialog box to b. This will be the name that appears in the Profile catalog

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4. Create another variable and give it the name ui_h, and the Label in dialog box will be h

For each variable we can choose whether to show it to the user or hide it by selecting Show or Hide in the Visibility column.

5. The two variables that have just been added should have their visibility set to Show but the two dimension variables should be set to Hide.

Add a formula

The formula cell can be used to define the logic that converts the input into a sensible result. Here we will create a simple formula that assigns the value of the user input variables to the corresponding dimensions.

1. But before doing that copy the value from the b1 Formula cell to the ui_b Formula cell and copy the value from the h1 Formula cell to the ui_h Formula cell
2. In the Formula cell of b1 type =ui_b
3. In the Formula cell of h1 type =ui_h

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4. Now increase the values in the ui_b and ui_h Formula cells to slightly larger numbers and the shape of the profile should change accordingly.

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You can now try changing the variables in the model.

5. Click the Save sketch button  
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Try using the profile in Tekla Structures. Note: You do not need to close the Sketch Editor while you do this.

6. Double click on a beam or column to open its Properties and click the Profile: Select... button, the Select Profile dialog box opens
7. Select the profile and type in some new values in the Value cell
8. Click Apply and OK
9. Click Modify in the part's Properties dialog box.

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You can also modify the profile's width and height by typing these values into the Profile field in the format shown below.

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Add variables to control the top and bottom flange depths

1. Add a vertical dimension from the top of the outer polyline to the top of the inner polyline and another one from the bottom of the outer polyline to the bottom of the inner polyline.

Note: If you were to add a dimension from the top of the inner polyline to the bottom of the inner polyline you would no longer have any freedom to vary any of the vertical dimensions because they would each be locked to their current value by the other dimensions.

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2. Add two new user input variables and link these to the new dimensions using the formula as shown below.

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Add a variable to control the web thickness

1. Add two more horizontal dimensions as shown below.

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We want both webs to have the same thickness. We can achieve this by adding a formula that sets one of the variables equal to the other variable.

2. Enter =b2 in the Formula cell of b3

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3. Add another user input variable for the thickness called ui_b1
4. Enter =ui_b1 in the Formula cell of dimension b2

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Add an image of the profile to the catalog

1. Create an image of the profile and save it as a .bmp file in the Bitmaps folder of the installation folder

For example, if you have installed Tekla Structures version 2018 to C:\TeklaStructures, it needs to be saved in C:\TeklaStructures\2018\Bitmaps.
 

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See also

Create a parametric profile by sketching (open profile example)
Create parametric profiles by sketching