Instability type 3

[StructuralSilver55]

I'm having instability type 3 problems with this structure. I dont know why when I solve one of them (i.e. deleting the node and creating an alternative part of the structure), another one problem appears (all of them instability type 3).

Thank you very much for your help!

[Rafal.Gaweda · Accepted solution]

[StructuralSilver55]

Thank you very much Rafal!

This is one of the most common mistakes, if we use panels over the bars , when the mesh is generated most times in the corners the points of the mesh are duplicated (also in intersection with other panels). Robot has any option to detect it? i.e. two points in less than 1 cm is a very common error. 

[Rafal.Gaweda]

Robot has any option to detect it?

http://forums.autodesk.com/t5/Robot-Structural-Analysis/API-addin-for-short-calculation-elements-det...

i.e. two points in less than 1 cm is a very common error. 

Use Correction (Edit \ Correct) to merge them.