How to Model Tension-Only Bracing in RISA-3D
Before reading this, be sure to check out the article linked below on X-Bracing. In RISA-3D, you can set a member to be tension-only by selecting...
Do you get an instabilities warning when you’re trying to do a simple 2D model in RISA-3D?
Below is the easiest way to test and fix the instability:
- Open the Node Reactions spreadsheet, and see which joint is unstable.
- In the Boundary Conditions spreadsheet, apply a Reaction to the joint in the degree of freedom that was LOCKED.
- Re-run the model and examine the Node Reactions.
If the reaction that is restraining the instability is showing a ZERO force or moment, then the instability is inconsequential to the results. Also, if the reaction that is restraining the instability is showing a non-zero force or moment, then you have a problem with the model that must be corrected for you to get valid results.
How Do I Avoid Instability Warnings in a RISA-3D Model?
Admin : Jun 13, 2011 12:00:00 AM
Have you ever received an instability warning when running a three dimensional RISA-3D model? This is because RISA-3D cannot build the stiffness...
How Should I Model Boundary Conditions for a Truss in RISA-3D?
Admin : Dec 16, 2010 12:00:00 AM
When it comes to trusses in RISA-3D, boundary condition definitions (pin vs. roller) can make a huge difference. Let’s take an example of a...