Dear All,
I'd like to know how the RSA is handling the offsets for frame members, for example suppose that there is an ordinary vertical column and if there are horizontal beams connecting to top node of that column with different offset settings. Then how the RSA deals with that, visual observation reveals that RSA creates artificial lever arm for differently connecting beams.
Your englightment will be appreciated.
Regards,
Solved! Go to Solution.
Solved by Artur.Kosakowski. Go to Solution.
You may say that an offset is a virtual rigid link with no real generation of 'the other' node.
http://docs.autodesk.com/RSA/2013/ENU/filesROBOT/GUID-DFB075D8-BD24-4946-8D4F-3175E93DEBA3.htm
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Thanks a lot indeed,
So basically how this maps into FEM theory implemented in RSA, by assuming that this rigid link has same as the beam properties Ix, Iy, Iz , A, poisson ratio etc.. except that Young Modulus is much more higher than the beam ?
Is my assumption correct ?
Regards,
For RLink approach yes, other wise the kinematic relations method (exact solution) is used.
Do we have the kinematic approach in RSA? Because I haven't seen such an option in any of RSA toolbar. Can you elaborate it ?
Regards,
They are used if RLinks are switched off. Mind that Sparse and Multi-threaded solvers due to their architecture force use of RLinks regardless of the setting in Job Preferences.
Hi,
This feature in which we are able to model an offset by a kinematic constraining rather than using Rlinks is really interesting, i wasn't aware that we were able to do that..
Can we do such a modeling (by kinematic constrains) for a diaphragm too? (i.e instead of assigning Rlinks between master node and slave nodes)? I mean, can we just constrain some d.o.f of selected nodes?
Can we do such a modeling (by kinematic constrains) for a diaphragm too?
Yes, the general rules I described above apply. You have to switch off RLinks and set the solver as Frontal, Skyline or Iterative.
Thank you for your reply Artur,
Do you mean that even if we model manually a diaphragm by defining manually rigid links between nodes, we can switch off the Rlinks in Job Preferences and then there would be kinematic constrains?
Thank you Artur,
One more question about Rlink elements (I don’t know if it’s needed to make a new post with another title about that).
What the help topic for RLINK type elements says that: “..provides the ability to use a concentrated mass matrix for dynamic problems” does it mean that when using RLINK elements the mass that correspond to all slave nodes is transferred and concentrated to the master node? In such case are we obliged to select Lumped without rotations for the mass matrix in the Modal Analysis Parameters in order to have only diagonal non zero values in the mass matrix (when provided that all nodes of each storey of the structure are slave ones to a master node)?
Thank you.
No, this only means that you have to use RLinks when you want to use lumped (concentrated) mass matrix for a model with rigid links.