Node instabilities in the RZ direction

[Anonymous]

I've got a warning about node instabilities, which I can't seem to be able to fix.

I don't understand why some of the nodes show instabilities whilst others (connecting similar members with similar releases) don't. For example, node 134 shows instability, whilst the equivalent node in the corner further left doesn't.

Any ideas?

[Artur.Kosakowski]

Try to block RX in definition of releases and RZ in the definition of supports.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

Thanks for the response.

You mean, block RX for all members, or just the members with the instabilities? I'm afraid that if I fix the both ends of the horizontal members in RX, they will transfer moments into the columns instead... 

[Artur.Kosakowski]

I'd block for all and then looked at MX values for these elements. You may also try partial releases.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous · Accepted solution]

Fixing rotation about Z in the supports seems to have worked.

thanks

[RHKRSG]

Sir , can you please explain how restricting rotation about x direction affects the instability in z direction , although the solution is working for me but I cannot understand how?