Robot Structural Analysis Forum
Welcome to Autodesk’s Robot Structural Analysis Forums. Share your knowledge, ask questions, and explore popular Robot Structural Analysis topics.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Curtain walls and modal analysis

14 REPLIES 14
SOLVED
Reply
Message 1 of 15
Romanich
3858 Views, 14 Replies

Curtain walls and modal analysis

Dear friends

Please check my conclusion about using Curtain walls in modal analysis. In first model I used Curtain wall and obtained the following results:

 

mod1.png

mod2.png

 

In second model I used equal loads and obtain different results:

 

mod3.png

mod4.png

 

Also, I made load to mass conversion with coefficient 1. Certainly, I checked model without any curtain walls and loads except self weight. The results coincided with the first model. My opinion is that we cannot use curtain walls in modal analysis, because they don’t taken into account. Maybe I'M wrong Smiley Happy

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Tags (3)
14 REPLIES 14
Message 2 of 15
Artur.Kosakowski
in reply to: Romanich

Two points:

 

1. Robot in order to be able to distribute load (including self weight) from curtain wall needs to detect supporting objects which can be either a panel edge or a beam. In your case the floor panels should be defined as starting/ending at the partition wall locations rather than as a single panels for the entire floor or you should add fake beams under the partition walls.

 

2. You may consider if the self weight of a partition wall should be modeled as a linear load at the location where the partition wall is 'now' as an owner of the building may change thits location (or add new) at some point in time ('later'). Perhaps you can think about adding some uniform load on the floor panel 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
Message 3 of 15
Romanich
in reply to: Artur.Kosakowski

Ok Artur, I've tried use fake beams (simple steel bar with diameter 1 cm) and modal analysis results not changed.

You absolutely right, I'm always add some uniform load on the floor panel. 

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Message 4 of 15
Romanich
in reply to: Artur.Kosakowski

Let me give detailed answer.

First model - curtain walls with fake beams:


fake_beams_plus_curtain_walls.png

fake_beams_plus_curtain_walls_Mxx.png

fake_beams_mode.png

 

Second model - equal loads without any partition walls and fake beams:

Equal_loads.png

Equal_loads_Mxx.png

Equal_loads_mode.png

 

As you can see, results from static analysis approximately the same. But results from Modal analysis is different. Maybe Robot have hidden ability to convert automatically generated forces in masses? I think the problem in this.

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Tags (2)
Message 5 of 15
Artur.Kosakowski
in reply to: Romanich

It is hard for me to discuss a particular situation without looking at the corresponding model but in general (some restrictions may apply) :

 

1. Cladding load (load generated by triangular and trapezoidal distribution method) is taken into account for static analysis provided the load carrying object can be detected (see bending moment diagram for case 2 on the attached picture 2)

2. Such load can be converted into mass (and this is standard rather than hidden functionality of Robot) in the way shown on picture 1.

3. Such generated mass is taken into account for modal analysis (in my example this is the only mass as the disregard density option is switched on in the parameters of the modal analysis).



Artur Kosakowski
Message 6 of 15
Romanich
in reply to: Artur.Kosakowski

Dear Artur

Please, check these two simple models.

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Message 7 of 15
Romanich
in reply to: Romanich

In Robot 2013 this problem still exist.

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Message 8 of 15
Romanich
in reply to: Romanich

Thank you, friends from Robot team! Service pack 1 for RSA 2013 solved this problem.

Do you find the posts helpful? "LIKE" these posts!
Have your question been answered successfully? Click 'ACCEPT SOLUTION' button.

Roman Zhelezniak

Robot Evangelist & Passionate Civil Structural Engineer

LinkedIn | Robot & Хобот | App Store for Robot
EESignature


Message 9 of 15
tony.ridley
in reply to: Romanich

I am running 2013 with SP1 and I'm getting the problem of curtain wall not being including in modal mass.  I will send file via large file transfer to Artur/Rafal if you are interested. 

 

Tony

Message 10 of 15
Rafal.Gaweda
in reply to: tony.ridley

Save as under new name as rtd without results, then zip, then send.



Rafal Gaweda
Message 11 of 15
tony.ridley
in reply to: Rafal.Gaweda

Here it is

Message 12 of 15

Tony,

 

Am I right saying that you have only claddings (no materials properties assigned) in your model? I think that you should replace them with curtain walls that have their self-weight included in the modal analysis.



Artur Kosakowski
Message 13 of 15

NO, I was running the model with claddings but also with user defined calculation options for mesh (check the "BONDEK" definition.  

 

I changed BONDEK to "Deck Slab" and it works OK.  

 

 

Message 14 of 15

Tony,

 

Please look at post 5 and the pictures attached there. I'm very sorry if I'm wrong but it seems that you missed the fact that to include self-weight of claddings you have to use load to mass conversion (and switch off use of self-weight in the modal analysis parameters). I made a quick test with the 'right' settings and Bondek panel calculation model assigned to panels 83 and 1931 obtaining similar results for introduced self-weight case case and modal analysis total mass.



Artur Kosakowski
Message 15 of 15

Yes thats what I was missing.  Thanks!

 

Tony

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report