Civil Engineering Association

dears freinds
dynamic analysis of structures with software versions 14.5-21 robotbat not mention any error messages, but if you throw the dynamic analysis of the same file with the version analyzed robot2009-2011 error messages show the unstable node type "n".
After much checking, I think these versions are a big problem

I answer to your question after 7 months and I think you have already finish your project , but this maybe help someone else.
There are three types of instability errors,
Type 1,2,3.
Usually type 1 is more serious.
I suggest you to check the offsets of your bar members , their releases [u]and their supports,

the basics that you mentioned are not the cause of this error message that appears when using the 2009-2011 version of the software robot.
analysis of the same file with versions 14.5-versions21 generates no error message.
if you've used earlier versions of the robot, you'll have the same conclusions.

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(09-11-2010, 10:03 PM)spy1551 Wrote: [ -> ]I answer to your question after 7 months and I think you have already finish your project , but this maybe help someone else.
There are three types of instability errors,
Type 1,2,3.
Usually type 1 is more serious.
I suggest you to check the offsets of your bar members , their releases [u]and their supports,

you talk about what project? you said that 07 months is here that I do this project !!!!! you astonish me.
you know that the transition from computer software is a breeze that does not have the time, especially for people who are competent.
tool is a computer game called play station

@rachid1968
Your first post was published at 09/02/2010.
In Greece we use different form for the date. I thought that it has been posted at 09 February. Obviously it was posted at 02 September 2010.
I am using Robot since the version 19 from the French Robobat.
I have been update to Autodesk Robot Structural Analysis 2009 but I didn't have this problem.

Your error is
Type 2 '' in node 492 ver RZ ''
So I suggest you to check the releases of the bars who interfer to the node 492 or the support in node 492[b].
For further and more partcular details I must see your model.
If you have saved in version 20 , you can sent it to me with email to check it with the version 2009.

thank you very much.
why the error message does not display for when I do the analysis is done with the robot versions version14.5 to version21.

My older models in robot 19 which don't have any errors they still don't have any errors in newer version.
Maybe this problems is caused because.
1. The reasons I told you in previous posts.
2. The data doesn't read correctly by newer versions.
3. Newer version do more checks.

You can also go to
ANALYSIS-VERIFICATION and check
Errors-Warnings-Notes

I still think that the problem is on your releases.
GEOMETRY-RELEASES and try to do change those members who interfer to node 492.

This error appears only when introducing the concept of floor infinitely rigid "diaphragm" for the dynamic and seismic study of the structure.
if you throw the dynamic study without introducing the notion of master node and slave node, no error message during the dynamic analysis.

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connectivity of nodes that operate in space is the same, namely the effect of continuity of bars ensure the complete transmission times deflections.
why the node 492 that triggers ERROR?

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3D MODEL WITH EFFECT OF DIAPHRAGM

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If your master node isn't part of the structure (e.g you have introduced it at the geometrical center) make sure that is properly supported. It''s support must block the degrees of freedom that have been considered free in the rigid diaphragm (UZ,RX,RY should be blocked.)
Your last images shows that you 've left some direction unblocked.

Analysis of these structures with robot14.5 version 21 does not generate any error message even if we introduce the concept of the diaphragm ....
it' here amazes me!

I've noticed no such problems with versions 21 to 2011. Rigid diaphragm works properly 100%. Maybe your model isn't properly red by 2011 version.