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:
In second model I used equal loads and obtain different results:
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
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
Solved! Go to Solution.
Solved by Romanich. Go to Solution.
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?
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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.
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
Let me give detailed answer.
First model - curtain walls with fake beams:
Second model - equal loads without any partition walls and fake beams:
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.
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
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).
Dear Artur
Please, check these two simple models.
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
In Robot 2013 this problem still exist.
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
Thank you, friends from Robot team! Service pack 1 for RSA 2013 solved this problem.
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Roman Zhelezniak
Robot Evangelist & Passionate Civil Structural Engineer
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
Save as under new name as rtd without results, then zip, then send.
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.
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.
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.
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