Dear STKO team,
I have manually written a model which consists of a 2D zeroLength Element and a 2D Elastomeric Bearing (Bouc-Wen) Element, resembling a base-isolated structure. Essentially there are 3 nodes in total, all of which are located at [0, 0]; the elastomericBearingBoucWen is connected to Node 1 and Node 2, the zeroLength is connected to Node 2 and Node 3. The model works fine.
However, when I try to replicate this in STKO, I've encountered this issue that a line of input "model BasicBuilder -ndm 2 -ndf 2 " is always automatically written in the STKO-generated "nodes.tcl" file, just above the definition of the third node which is only connected to the zeroLength element. Now since the "nodes.tcl" file is always sourced ahead of the "elements.tcl" file in "main.tcl", when running the analysis, OpenSees would tell me in the WINDOWS command prompt that the elastomericBearingBoucWen element cannot be generated because I've got only 2 ndf. This is not an issue when writing the .tcl file manually as I could just type "model BasicBuilder -ndm 2 -ndf 3 " at the begining of the file and leave it. But how can I enforce "-ndf 3" in STKO so to generate the elastomericBearingBoucWen Element?
I'm affirmative the rest of my STKO model works fine, because if I replace the elastomericBearingBoucWen element with a zeroLength element in STKO so that in such a case -ndf 2 is good for all, the model works just fine and the results are identical to those from the corresponding manually written .tcl script.
Many thanks!
Ziliang
ndf problem
Re: ndf problem
If you want the nodes of the zero length to have 3 DOFs in 2D, make sure you tell STKO to use the U-R (displacement-rotation ModelType)
- ZLUR.png (26.22 KiB) Viewed 1390 times