topic Node instability in Robot Structural Analysis Forum

Node instability

Anonymous — Tue, 03 Nov 2015 21:59:49 GMT

This is my first time using Robot--I'm trying to do a basic structural analysis for my Revit project. When I import and run calculations in Robot I get a series of messages:

and then when I look at my max displacements and deflections they're really wild and all over the place. What should I do to fix this so that I don't get really insane results and can actually use Robot?

Re: Node instability

Rafacascudo — Tue, 03 Nov 2015 22:51:19 GMT

Search forum.look for similar posts.
Click on the error messages and unstable nodes will be highlighted.
Sometimes it is obvious why the node is unstable.Lack of support, too many bar releases, etc.
Instabilities of type 1 and 2 cannot be ignored. Type 3 can be ignored if displacements are coherent with structure size and loads.
If you still cannot solve the problems by yourself, send the model

Re: Node instability

Anonymous — Wed, 04 Nov 2015 06:04:14 GMT

I looked through a variety of related posts and am still not quite certain what's wrong. There are some bars that look to be attached in the Revit analytical model but then aren't in Robot? Here's a link to the .rtd file.

Re: Node instability

Rafal.Gaweda — Wed, 04 Nov 2015 08:05:47 GMT

Why do not you look at your model , esspecially in nodes reported in warning messages, and correct it first?

It is inaccurate.

Re: Node instability

Anonymous — Thu, 05 Nov 2015 02:08:51 GMT

Because the elements were connected and I can't quite figure out how to move the nodes to connect to the nearby bars of the truss? I've never used Robot before--and I'm trying to just get quick results to make sure my Revit model is relatively accurate.

Re: Node instability

Rafal.Gaweda — Thu, 05 Nov 2015 08:20:27 GMT

Because the elements were connected

I have shown you - they are not connected.

and I can't quite figure out how to move the nodes to connect to the nearby bars of the truss? I've never used Robot before--

Edit \ Edit \ Move

or

Edit\ Detailed Correct -> to line

and I'm trying to just get quick results to make sure my Revit model is relatively accurate.

Unfortunately your Revit analystical model is not accurate enough.

Re: Node instability

Anonymous — Fri, 06 Nov 2015 07:35:42 GMT

Thanks! I've tried to connect all of the members and most of the warning messages have gone away--but I cannot get rid of node instability warning for four nodes even though they look connected.

Is there anything I can do to fix this?

Re: Node instability

Rafal.Gaweda — Fri, 06 Nov 2015 08:01:17 GMT

Without the file... too many releases