Zerolength drift

[hbma]

Hi,
What does "recorder drift" show when used for a zerolength element? I mean it might not be drift ratio anymore. Is this just displacement between 2 nodes of zerolength element?

kind regards

[fmk]

drift recorder takes the difference between nodal displacements and divides by the difference between the nodes .. if zero difference you should get a divide by 0 error.

[hbma]

The code has proceeded without any error, although the difference is 0. I have obtained data and diagrams and i dont know what they represent.
Indeed, i have used zerolength to model isolators in my project,

[fmk]

you should have seen an error message if all elements have zero length in dirn of interest .. if some don't have zero length you will record info on those ONLY .. here is a sample script.


model Basic -ndm 2
node 1 0 0 0
node 2 0 0 0
uniaxialMaterial Elastic 1 100.
element zeroLength 1 1 2 -mat 1 1 1 -dir 1 2 3
fix 1 1 1 1

recorder Node -file node.out -node 1 2 -dof 1 disp
recorder Drift -file drift.out -iNode 1 -jNode 2 -dir 1

timeSeries Linear 1
pattern Plain 1 1 {
load 2 1. 1. 1.
}
analysis Static
analyze 1

[SUMMERER]

The code for one case is "recorder Drift -file drift1.out -iNode 1 -jNode 2 -dof 3 -perpDirn 1" , "recorder Drift -file drift2.out -iNode 13 -jNode 2 -dof 3 -perpDirn 1", and the zerolength element is consist of node 1 and node 13.
Do the above two codes mean curvature? The curvature of the zero-length element can be obtained by obtaining DRFT1-DRIFT2?
PLEASE HELP ME!
Looking forward to your reply!

[selimgunay]

No these are not related to curvature.

[SUMMERER]

No these are not related to curvature.

Thank you for your answer! May I ask what does this mean?

recorder Drift -file drift1.out -iNode 1 -jNode 2 -dof 3 -perpDirn 1"

Looking forward to your recovery. Thanks again

[selimgunay]

This is a recorder to obtain the drift (displacement normalized by length of the member) between nodes 1 and 2 for DOF 3. You can find explanations of the parameters used in this recorder here:

https://opensees.berkeley.edu/wiki/inde ... t_Recorder

[SUMMERER]

This is a recorder to obtain the drift (displacement normalized by length of the member) between nodes 1 and 2 for DOF 3. You can find explanations of the parameters used in this recorder here:

https://opensees.berkeley.edu/wiki/inde ... t_Recorder

Thank you for your reply and information. I have learned it, but I still don't know " -Dof 3-perpdirn 1" means. Why divide the rotation between two nodes by the distance between them?
Looking forward to your reply

[selimgunay]

The common usage of this is for horizontal displacements to obtain the drift ratio as the displacement divided by the length of the element. It is not so meaningful for rotations.

[SUMMERER]

The common usage of this is for horizontal displacements to obtain the drift ratio as the displacement divided by the length of the element. It is not so meaningful for rotations.

Thank you for answering my questions, I can get your enthusiastic answer is my luck!