Any models to simulate isolation system?

cctvcctv · Post by **cctvcctv** » Wed May 18, 2005 2:56 pm

such as Bouc Wen model?

berktaftali · Post by **berktaftali** » Thu May 19, 2005 6:12 am

There happens to be a uniaxial material model for BoucWen in OpenSees:

uniaxialMaterial BoucWen tag? alpha? ko? n? gamma? beta? Ao? deltaA? deltaNu? deltaEta?

No documentation, though ...

Hope this helps...

silvia · Post by **silvia** » Thu May 19, 2005 6:31 am

another undocumented feature........ we have to find out if it is still supported in the latest version!!

berktaftali · Post by **berktaftali** » Thu May 19, 2005 7:18 am

Well, I pulled it out from the source of v1.6.2. The CVS says it has last updated 2 years ago, so proceed with caution ...

motalaat · Post by **motalaat** » Thu May 19, 2005 3:45 pm

Yes!!! Docuemtation again. I ran into at least one occasion where I wanted to use this model (which you can only know of if you happened to be writing your own code in OpenSees for something else - or kept a close eye on the discussion forum) but couldn't because of lack of it. Not only is there no documentation, but there seems to be not that many people who know that the model exists or who authored it. By the time I knew, I had already resorted to using a parallel spring-and-damper material model.

This brings me to supporting Silvia's point about requiring people to submit valid documentation before accepting their products into OpenSees (hey, we all complain about documentation but when it comes to be our turn to graduate, I bet we will not be that eager to sit down and do it). By the way, the author is Terje Haukaas if you are interested, by looking in the C++ file. You may contact him for documentation if he has any in e-format. terje@civil.ubc.ca and http://www.civil.ubc.ca/faculty/THaukaas/

stealth_mode · Post by **stealth_mode** » Sat Dec 16, 2006 12:32 pm

Sorry to bother, but have you solved the un-documented parameters problem?

I have the original papers (Wen, Baber and Noori). Even though, I couldn't have solved my problem:

I have a force-displacement curve (actually, capacity curve of a 2-d frame) and I want to represent this curve by using an approximate Bouc-wen model generated curve. I can not find how to choose the parameters (alpha, k0, A and n) to define the physical parameters (initial stiffness, post-yield stiffness ratio, yield strength and displacement) combinatorially. I can define initial stiffness properly (initial stiffness=k0), but when I play with the numbers (actually, A value) to converge to the proposed yield strength, the initial stiffness changes and I do not know what to do with these 4 parameters

silvia · Post by **silvia** » Sun Dec 17, 2006 10:28 am

there are some features in opensees that are not documented on purpose, as they have not proven to be reliable!