Rigid links in ROBOT - how are distributed forces

[gajewskijarek]

I have a question to "Rigid Links". What is the rule for the distribution forces from master node to the slaves nodes. Because I did a simple test for transfer Moment and Force (figure under), I blocked the UZ for the slaves nodes.

It is looks like depending from geometry of the slaves nodes.
I also tested an centric and eccentric master node position in terms to the columns.
Answer is important when we use "rigid links" for example to connect beam element and shell element.

[Artur.Kosakowski]

You can think of a rigid link as of a very rigid bar element connecting a master node with a slave one. The unblocked d.o.fs can be then assumed as corresponding releases applied to this bar at the slave node end.

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.

[gajewskijarek]

Ok. That's right - for simple situation. But I still don't know why I received the results on the below figures.

In HELP (F1) I didn't find the answer.
It must be some rule according to which forces transfer from Master node to Slave Nodes ( when we have more slave nodes) - I suppose it's geometric rule.  Most of the programs (FEA) have the similar function "rigid links".

[Artur.Kosakowski · Accepted solution]

Some programs have  some geometric rules and if I remember correctly STAAD uses or at least used to use something like that (sort of having the same displacements for connected nodes) but in Robot it is as I described it. Try to replace rigid links with rigid bar elements with appropriate releases at the slave nodes when applicable and compare the results.

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.

[Tuctas]

Can we know how much rigid are these fictitious bars that connect the master node with the slave nodes? I mean the arithmetic value of the rigidity of these rigid links (in all d.o.f's).

[teixeiranh]

Why would you want to know that?

[Tuctas]

The understanding of the exact simulation of rigid links always maters.

[Artur.Kosakowski]

As far as I remember it is either 1000 or 10000 time more rigid than the elements it connects.

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.

[Tuctas]

O.k. However, if you find out which of the numbers (1000 or 10000) is used, please let me know. Does this amplification concerns all the d.o.f's (the same factor for all d.o.f's)?

[Artur.Kosakowski]

10000 and yes 

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.

[Dirgs]

Hello,

I've some trouble on an analysis model of a small building. The model was already partially constructed and it has membrane rigid links created on each story, which I cannot delete.
Already had tried delete the nodes on rigid link table and by graphic interface, but each time I run it, they appear again...Can you please help with this?

Thanks,

Dirgs

[Rafacascudo]

This comes from " panel calculation model"

your slabs are assigned with a type that has partial (XY) or full stiffenning(rigid body) on "connection of nodes for the slab"

If you don´t know the type which is assigned to your panels goto View/Display.../panels/panel description/calculation model type