Why do I get an analysis element too short error/warning?

Question

Why do I get "an analysis element length is lower than the limit", error or warning?

 

Answer

The “analysis element too short” error or warning, is reported when an analysis element is shorter than the error or warning limit set under the Home ribbon > Model Settings > Validation page, as shown in the screenshot below.

 

We build the physical model by placing the beam, column or other objects between support points. Behind the scenes, Tekla Structural Designer builds the analysis model for you automatically.

Two incoming members will result in a beam split into three analysis elements

 

None of the analysis elements above will result in an error or warning because the length of each analysis element is greater than the limits set under the Home ribbon > Model Settings > Validation page

The screenshot below displays the default length limits set in Tekla Structural Designer.

With the settings shown below;

• an Error will be reported if the analysis element length is shorter than 10mm
• a Warning will be reported if the analysis element length is shorter than 50mm in length

 

Example

In the example below, there is a brace on gridline A, which is intended to connect to the top of the column on gridline A/1.

In the Structure scene view it would appear to be connected at the intended point.

 

If you Validate the model, an error is reported.

Double clicking the validation error will switch the active Scene view to the Solver view and highlight the location of the issue for further investigation.

In the Properties window it reports the length of the analysis element. In this example it is 8mm, which is less than the error limit of 10mm.  

 

To resolve the issue you need to re-position the brace so that it connects to the node at the top of the column.

 

You could also have adjusted the limit to greater than 8mm, however, having very small analysis elements can cause ill-conditioning of the matrix during analysis. See the linked article to the right for further information on this.