VisualAnalysis Tutorials: Validating the Model and Results
The purpose of this tutorial is to demonstrate how model and results can be validated. These features can be very helpful with trying to find problem spots and explain why a model may not be behaving correctly.
Modeling the Structure
Create a new plane frame project.
- Draw a 10 ft long beam with both supports "Free from external restraints"
- Specify the beam as a "W 21x50" shape
- Apply a uniform Dead Load of "-5 K/ft" in the Y direction
- Apply a nodal Dead Load of "-5 K" to the right side of the beam in the X direction
Your model should look similar to the figure below:
Validating the Model
From the main menu, select the Analyze | Check Model for Errors command to check the model for errors. You will now be prompted with a menu box stating that "Changes should be made to your model: 1 members should be removed." Presented options are to choose "Yes" to fix problems, choose "No' will ignore problems, or "Cancel' will abort. Choose No. The results of the check will now be shown. Problems will be listed with possible solutions.
This check can be helpful if done before an Analysis to ensure that it will analyze correctly, or after an Analysis has failed and you are trying to isolate the problem. This check can also be helpful in erasing members that may have been drawn accidentally. Make the model stable by specifying the left support as fixed, creating a cantilever. Now, Analyze your model using a First Order Analysis (Model View-Modify Tab of the Project Manager).
Validating the Results
In the Result View window, select the "Results" tab in the Project Manager and expand the "Statics Check" heading. You can now change which direction you want the Static Check is taking place. The X and Y directions show a 0% error. Select the "Z Moment" direction. You will notice an error of 0.06%. Note the value of this statics check for First Order results.
Now, select P-Delta Analysis (Model View-Modify Tab of the Project Manager) and Analyze your model. Look at the "P-Delta" results for the "Z Moment" direction. The 0.001% error is lower because the software is now taking into account the displaced locations of the loads.
Use the Analyze | Result Validation Checks command to validate the results. This is another way for VisualAnalysis to find errors in your model. In this case, no errors are found. Use caution with these automated checks, because not all errors can be detected. The Check Model for Errors and Result Validation checks can be very helpful to make sure your model is behaving accurately and displaying reasonable results. These checks may not catch every mistake, but are a very good way to help locate a problem, if one exists. You can also create a report of the Statics Check for analyzed load cases using the Report | Report Wizard. This report will list the load case, % error, etc. If the error is very small as in the case of our tutorial model, the Status will be listed as "Ok".