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Incorrect load distribution for panels with openings filled with other panels

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Message 1 of 9
PatrickEC
467 Views, 8 Replies

Incorrect load distribution for panels with openings filled with other panels

As you can see in the picture below, there is a large panel with two openings. There is also a small panel with increased load inside of each of the two openings.

 

Load_distribution_01.png

 

Load_distribution_02.png

 

The load distribution for the larger panel apparently ignores the openings and consequently overestimates the total load. After deleting the smaller panels, the larger panel load distribution is correct.

 

The workaround that I am currently using is splitting the larger panel such that there are no openings.

 

I attached models for your reference. The load distribution in Load distribution.rtd is incorrect. The total reaction for Load Case 1 should be 700sf x 100psf = 70000lbs, but is 80000lbs.

8 REPLIES 8
Message 2 of 9
Rafacascudo
in reply to: PatrickEC

You don´t need to create an opening and then create another panel. Just create the larger and the (inside) smaller panels. Robot is smart!!  Smiley Happy

 

To correct your model , just delete the openings( objects 24 and 25)

 

To check the "real" larger panel , select it and open/edit in another window



Rafael Medeiros
Robot Structural Analysis

Message 3 of 9
PatrickEC
in reply to: Rafacascudo

@Rafacascudo

 

Thanks for your suggestions. This is not how I modeled it, it is exported from Revit.

 

Your solution works, but I cannot use, because I have a very large model and would need to manually delete dozens of openings. And if I delete all the opening in the model, than the empty openings will be lost.

 

Any other ways to fix it?

Message 4 of 9
t.sautierr
in reply to: PatrickEC

Sort your pannel by area, sort your openings by area, export to excel, when you find to areas exactly the same keep the number of the opening, make a list and deleted the list in RSA?

Message 5 of 9
t.sautierr
in reply to: t.sautierr

No better : select your small pannels, select the points related to this pannels by the quick selection, and then select the objects related to the previous points. Unselect pannel and points, and your openings will remain selected, ready to be deleted

Message 6 of 9
Rafacascudo
in reply to: PatrickEC

Patrick,

 

  Do the " dummy" smaller panels come also from Revit or were they modelled in Robot?

 

  I opened your model again and if you change the calculation model to shell instead of " two way" and assign proper material to the panels , you will not have to delete the openings and there will be no problems with the load distribution .



Rafael Medeiros
Robot Structural Analysis

Message 7 of 9
PatrickEC
in reply to: t.sautierr


@t.sautierr wrote:

 select the points related to this pannels by the quick selection


Could you please elaborate? I do not understand what to do here.

Message 8 of 9
PatrickEC
in reply to: Rafacascudo


@Rafacascudo wrote:

  Do the " dummy" smaller panels come also from Revit or were they modelled in Robot?



Everything comes from Revit. I did not model anything in Robot.


@Rafacascudo wrote:

  I opened your model again and if you change the calculation model to shell instead of " two way" and assign proper material to the panels , you will not have to delete the openings and there will be no problems with the load distribution .


Thanks for this observation. I have a reason not to use shell elements. I have a steel structure with steel grating floors. Therefore, I use panels only for load transfer and it is not desired to include panels in the calculation model.

Message 9 of 9
Rafacascudo
in reply to: PatrickEC

If you don´t want finite elements , then , I think there´s no easy way to select the openings that have the same  small slabs´s contour.

 

   Maybe you can try to select all the small slabs ,all the openings and open them in another window("edit in new window"). Them , it should be easier to select the slabs and openings that are " together". Again ,Open these in a new window , both will remain selected . Then unselect all your small slabs through quick select.Only the openings you need to delete will remain selected. Delete them.

 

Can´t think of an easier way. T. sautier method would be nice if we could select the objects/panels by its contour points, but I don´t think it is possible.

 

Maybe Rafal ,Artur , or Pawel can suggest a better solution!

 

 



Rafael Medeiros
Robot Structural Analysis

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