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instability of type 1 / 2 /3 ...anybody can help ?

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Message 1 of 6
raasha
2031 Views, 5 Replies

instability of type 1 / 2 /3 ...anybody can help ?

Hi guys ..

 i'm trying to study a Stadium roof as a truss 3D model using autodesk robot structurel analysis professionel 2011..

but i'm getting a lot of errors ( instability of type 1 / 2 /3 )..

this is the autocad drawing for the roof 

and i have attached the rtd file for the model 

 

plz reply i dnt have alot of time ...

stade.jpg

Tags (1)
5 REPLIES 5
Message 2 of 6
Artur.Kosakowski
in reply to: raasha

Geometry > Structure type > change from 3D truss to 3D frame. Then add releases or use truss bar attribute where needed.

 

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.

 



Artur Kosakowski
Message 3 of 6
raasha
in reply to: Artur.Kosakowski

thank u 

 

i want to use HEB 160 as a section for bars (frensh code ) but i cant find it ..can u help plz ?

Message 4 of 6
Artur.Kosakowski
in reply to: raasha

Add e.g. EURO section database in the Job Preferences.

Euro section database.PNG



Artur Kosakowski
Message 5 of 6
jo2ny
in reply to: Artur.Kosakowski

Another Instability Type 2 in my model.

Attached rtd file.

 

I keep getting instability type 2, dir. RY in the center of the X bracings, only in the first frame. (node 1056)

I tried:

- checked end bar releases, seems fine by me

- deleted bracings in the first frame, copy bracings from the second frame ( i don;t get instability anywhere else)

- moved all bars and panels 20m away, deleted isolated nodes left behind, moved everything back in position

- i copied the midle frames (2 columns, 1 beam, the X bracings) to another rtd file., ran the model, no more instability

None of these worked...

 

Q1: Any idea how to solve the problem? Should i copy absolutely everything into a new rtd file; will that work?

Q2: I posted this in an existing topic. Should I have opend a new topic or it is better this way ? 

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Message 6 of 6
Artur.Kosakowski
in reply to: jo2ny

In this very case the Sparse solver (Automatic) should report type 3 instead (large difference in stiffness of elements). You can select the Sparse_M solver instead.

 

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.



Artur Kosakowski

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