hi every one,
i read the topics regarding the support displacements,but i still have problem.
suppose that we have a line in x direction,existing on a pipe rack which has a deflection in x,z direction due to seismic.

what is the method if we want to put a rest support and induce the displacements of the rack??
here is what i think:

for example node 20.

20 cnode to 1020
+y restraint

now we go to displacements and put the displacements of the rack in X,Z direction to the Cnode.

now my question is,while we just connect the two nodes in +y direction,so the movement of the rack in X,Z direction will not be induced to the node!!!

and what will be the situation if we want to guide the line?

i will appreciate if anyone can help.

Hi khodayar

"now my question is,while we just connect the two nodes in +y direction,so the movement of the rack in X,Z direction will not be induced to the node!!!"

No it will not be introduce to the node.You will find some effect if you put rest support with frictional co efficient.
If no friction is used then structural behavior of piping behavior wiill be entirely different in terms of axial & lateral movement.

Now if guide is used in connecting node that guide support pull pipe to follow structural lateral deflection.

Again you if add axial stop with rest + guide with CNODE then than support force pipe to follow lateral+ axial movement same as structural.Then piping deflection & structural deflection will match in terms of X & Z movement.

Hope that clarify the point.


Regards

Habib

Habib,
tnx for your comment.

if you refer to the application guide of caesar(single directional restraint and guide),you will see that they put a guide support for a pipe on a structure and also put the whole displacements in all direction for the CNODE.(including the axial movement)
it means that they consider that even if you do not have a support and cnode in axial direction,but the displacement will be induced to the piping.
it is still a little confusing for me!!

kind regards,

Hi khodayar

Yes I take a look at application guide.
I like to understand phenomena separately.
First support +Y at 20 reference to CNODE 1020. Node 20 is related to node 1020 by +Y only.

Now come to node 1020 that is structure placed at global reference with anchor means ( with displacement 0,0,0,0,0,0).
If I like to put displacement I have to put like ( displacement 3,0,3,0,0,0).

We can not put Dx=3 & dz =3 rest leave blank. Because that is structural support reference.
Same as when we put nozzle displacement value manually.

Just check one thing Put support +Y at 20 Cnode 1020. Do not use node 1020 in the model , then node 20 will be considered as free point ,not support.

Regards

Habib