Force Slabs to Span One-Way

[Anonymous]

Hi Guys,

I am attempting to force some of the panels in my model (see pdf) to span transveresly one-way.

I changed the panel calculation model to match the intent, and I changed the X axis of each panel to match the one-way span.

http://docs.autodesk.com/RSA/2012/ENU/filesROBOT/GUID-F57A58F9-81AA-4410-84EA-6BFFD83D115-214.htm

http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Floors-span-direction/m-p/3349655/highlight/...

• Finite Element Type: Shell  ( I need to know the BM and Shear and axial forces in the slabs)
• Rigid connection of nodes for the slab - diaphragm-stiffened - Full Stiffening  (I wanted slab diaphragm actions to limit effects of horizontal forces)
• Transfer of loads - simplified - One Way   (Slabs were originally designed to span continuously transveresly one-way and therefore contain a greater amount of reinforcing in the transverse direction)

I tried to verify the model, but got these errors: 

"Forbidden use of a compatible node or a support in a slave node of the rigid link".  Which affected all the nodes around the one-way slabs I defined.

"The load has not been distributed correctl | there are no objects that carry the load"

Changing the slabs back to Panel calculations model default "Shells" didn't fix the problems.

At some point I also changed the vertical panels with linear releases to diaphragm action, again to limit effects of horizontal forces.   But changed the setting back to "Rigid connection of nodes for the slab - Without Stiffening" after getting the error "incorrect panel calculation model" (see pdf).

What panel calculation model settings should I select to get the indicated slabs continuously spanning one way?

Can I have the vertical panels with linear releases providing stiffness transversely?

Are the vertical panels with linear releases affecting the one-way spanning slabs?

As you probably guessed, this is a development from yesterdays post.

http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Panels-with-Linear-Releases-Create-Isolated-...

I've sent a message to Autodesk strucutral support with the problem model.

Thanks.

[Rafal.Gaweda]

Andrew,

while waiting for the file please use updated robot version. Please install all available SPs.

(It will not solve all your problems \ questions but it helps ).

[Anonymous]

• Finite Element Type: Shell  ( I need to know the BM and Shear and axial forces in the slabs)
• Rigid connection of nodes for the slab - diaphragm-stiffened - Full Stiffening  (I wanted slab diaphragm actions to limit effects of horizontal forces)
• Transfer of loads - simplified - One Way   (Slabs were originally designed to span continuously transveresly one-way and therefore contain a greater amount of reinforcing in the transverse direction)

With full stiffened diaphragm you won't see bending or shear in your slab I think.  Full stiffening means parts of slab cannot deflect relative to another therefore no bending.  Just use flexible stiffening

You are probably not getting the panel to work because is it's spanning one direction only but there are no supports on at least one side of those slabs (in either x or y direction) so where can the load transfer to?

What panel calculation model settings should I select to get the indicated slabs continuously spanning one way?

Use an orthotropic slab to make the slab truly one way spanning.

Can I have the vertical panels with linear releases providing stiffness transversely?

Vertical panels will still act as stiffeners for lateral loads

Tony

[Artur.Kosakowski]

Rafal will have a look at your file but I think that in the typical situations you can try to mesh panels and use the thickness definition shown below:

[Rafal.Gaweda]

Andrew

"Forbidden use of a compatible node or a support in a slave node of the rigid link".  Which affected all the nodes around the one-way slabs I defined.

Use RLINKS

"The load has not been distributed correctl | there are no objects that carry the load"

I do not see this warning message, Have you generated model before running verification ?

Changing the slabs back to Panel calculations model default "Shells" didn't fix the problems.

 Have you generated model before running verification ?

At some point I also changed the vertical panels with linear releases to diaphragm action, again to limit effects of horizontal forces.   But changed the setting back to "Rigid connection of nodes for the slab - Without Stiffening" after getting the error "incorrect panel calculation model" (see pdf).

http://docs.autodesk.com/RSA/2012/ENU/filesROBOT/GUID-F57A58F9-81AA-4410-84EA-6BFFD83D115-214.htm  -> Note: Diaphragms can be generated only on horizontal panels in the XY plane.

What panel calculation model settings should I select to get the indicated slabs continuously spanning one way?

Can I have the vertical panels with linear releases providing stiffness transversely?

Are the vertical panels with linear releases affecting the one-way spanning slabs?

Answered by Tony and Artur above

[Romanich]

Artur, Rafal - can you create development request to remove this limitation for diaphragms ( only on horizontal panels in the XY plane) ?

[Rafal.Gaweda]

Which limitation?

Forbidden  use of supports in slave nodes ?

[Romanich]

Note: Diaphragms can be generated only on horizontal panels in the XY plane.

[Rafal.Gaweda]

Rigid links are defined using global directions so it is not possible to correctly define "diaphragm" on inclined plates, walls in different planes than parralell to ZX ZY global planes.

[Anonymous]

Romanich,  could you not just bump up membrane stiffness using user defined stiffness matrix to replicate this effect?  

[Romanich]

Rafal, I'm understood. Too bad, but..

Tony, in this case (with bump up) we obtain error. Please, read paper by Ed Wilson.

[Anonymous · Accepted solution]

"With full stiffened diaphragm you won't see bending or shear in your slab I think.  Full stiffening means parts of slab cannot deflect relative to another therefore no bending.  Just use flexible stiffening"

OK.  I tried your suggestion, but the results didn't look correct.  I've now made them all default shells.

"You are probably not getting the panel to work because is it's spanning one direction only but there are no supports on at least one side of those slabs (in either x or y direction) so where can the load transfer to?"

The slab is supported on all edges.  I attached a screenshot not displaying the supports.

"Forbidden use of a compatible node or a support in a slave node of the rigid link"

Using RLinks has solved this problem, but i don't understand why.  Rafal, can you elaborate on what that error means?

"Diaphragms can be generated only on horizontal panels in the XY plane.".  

Noted.

I was unable to replicate the load distribution error.  Must have something to do with the model generation.

Artur, thanks for the advice on orthotropic slabs.  Now I just have to  decide on realisitc stiffness coefficients to account for the steel reinforcing in each direction.

Cheers.

[Rafal.Gaweda]

Using RLinks has solved this problem, but i don't understand why.  Rafal, can you elaborate on what that error means?

http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-331BE2BD-5672-40EA-A6B5-D4420E78F379.htm

http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-88C4C842-5D90-4E85-8F8C-D47D6E474E29.htm?highl...