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Beam offsets

15 REPLIES 15
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Message 1 of 16
stefanlatea
2826 Views, 15 Replies

Beam offsets

Hi,

 

I try to improve my structural design model.

 It's possible to set offset member length of "T" beams on column faces? (now the program set the beams offset at theyr edge overlap).

In Etabs it can set an rigid zone factor for the elements connections. I try to set for my structure, putting all the partial stiffness coefficients 0,8, for example, and assign to all beams and column elements but i received some errors at calculation. How can I do?

 

Thanks

 

 

15 REPLIES 15
Message 2 of 16

reduce length and stiffness.PNG

 

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Artur Kosakowski
Message 3 of 16

Thank you, Artur! 

 

but, which is the explanation for  stiffness coefficient change just for Ry?

 

i understand there is no chance to limit offset length beams at column faces (for my situation)

 


Regards

Message 4 of 16

but, which is the explanation for  stiffness coefficient change just for Ry?

 

That was just the example of the definition of such release type. You can apply the reduction for other d.o.fs as well.

 

 

i understand there is no chance to limit offset length beams at column faces (for my situation)

 

You can define any values using UX (local) fields

 

UX offset.PNG

 

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Artur Kosakowski
Message 5 of 16
Tuctas
in reply to: stefanlatea

However, it will be really very useful if T beam's lenght could be automatically reduced directly on columns sides..
Message 6 of 16
Artur.Kosakowski
in reply to: Tuctas

Have you tried to use the offset definition from the message 2 above?

 

http://docs.autodesk.com/RSAPRO/2014/ENU/filesROBOT/GUID-63486561-1D79-4056-A945-890FD7CED7AB.htm



Artur Kosakowski
Message 7 of 16

one more thing,


What I noticed is that if i add for all beams and columns, 1 on Ry stiffness coefficient (I think it is for a total joints stiffness) the structure period will increase that means a less rigidity for entire structure. it's not that i expected.

Thank you, Artur.

Message 8 of 16

I have made a quick test and in my case the results for model with no releases and 1.0 partial coefficients RY are the same which is what is expected. Could you attach your model please?



Artur Kosakowski
Message 9 of 16
Tuctas
in reply to: Artur.Kosakowski

  Have you tried to use the offset definition from the message 2 above?

 

  The results by using that option is what is shown in picture "xy view" in message 1. The offset is bigger than the distance between the center and the side of columns (as it should be).

Message 10 of 16

sure,

 

now, I see that I get and error on calculation

Message 11 of 16

In Robot elastic releases are provided by use of DSC elements. In the current version of Robot these elements are not compatible with the offsets therefore Robot terminates the analysis when both applied to the same bars (if you force it to run calculations the obtained results will be incorrect).

The workaround is to replace offsets with rigid links connecting 'shortened' beams and columns with their 'intersection' nodes while keeping the definition of elastic releases as they are.

 

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 12 of 16

Hi Artur,

 

"...Robot terminates the analysis when both applied to the same bars"

 

I have a model where I have elastic releases and offsets (that curved bridge) , but not applied to the same bars . The error is also showing up.

 

These 2 bars (bridge girder with offset and little bar simulating elastomeric support) are connected by a rigid link.

 

I would like to keep the offsets instead of rigid links as it saves me a LOT of time.

 

Is there any other way to do it?



Rafael Medeiros
Robot Structural Analysis

Message 13 of 16

Try this settings:

 

settings.PNG

 

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Artur Kosakowski
Message 14 of 16

So , if it´s not on the same bar(offset and elastic release) ,I may ignore the Error warning and trust the results???

 

I did a test(simple beam) and even with offset and elastic release applied to the only bar available  , the results were good!!!

 

In which particular case should I trust this error warning??



Rafael Medeiros
Robot Structural Analysis

Message 15 of 16
Tuctas
in reply to: Rafacascudo

In my opinion, just vote the following request on the whish list...:

http://forums.autodesk.com/t5/robot-structural-analysis/offsets-in-robot/idi-p/5256537

 

Message 16 of 16

They should not be used on the same bar

 

offset and release.png

 

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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