element death and birth

amceuma · Post by **amceuma** » Wed May 14, 2008 11:01 am

Hi Dr.silvia
Are there elements such as element death and birth (in ANSYS) in opensees?
if the answer is NO how can I establish this type of elements?
Thanks

silvia · Post by **silvia** » Wed May 14, 2008 12:40 pm

you might have to develop your own.

pejman_opensees · Post by **pejman_opensees** » Wed May 14, 2008 9:18 pm

Although Opensees does not have such capability same as Ansys or Abaqus, there is another approach that you might find it useful for at least element death. As Silivia said, you might want to develope such thing by your own, but through the use of fatigue material (Uriz 2004), you will be able to model element death somehow.

silvia · Post by **silvia** » Wed May 14, 2008 9:33 pm

i don't know what these element events are, but you can remove/add an element in the midst of an analysis.

amceuma · Post by **amceuma** » Thu May 15, 2008 4:05 am

Thanks for your reply
I want to analyze X bracing system that one of this braces act in + direction and other act in reverse direction.How can I remove/add in midst of an cyclic or eigenvalue analysis?

silvia · Post by **silvia** » Thu May 15, 2008 5:54 am

use the remove command.
remove element $elementtag

make sure you remove the loads/recorders on it.

amceuma · Post by **amceuma** » Thu May 15, 2008 11:36 pm

Dear Dr.silvia
thanks foy your reply
I 'd appreciate if you help me how can I use add/remove command for mentiond purpose (in midst of eigenvalue analysis for determining the period of structure) for example on 1-story 1-bay, X braced frame.
Thanks before

silvia · Post by **silvia** » Fri May 16, 2008 5:31 am

you just have to do two eigenvalue analyses, one before one after you remove the elements.
i have never done this, so you might want to play with something simple.

amceuma · Post by **amceuma** » Fri May 16, 2008 8:25 am

Thanks Dr.silvia
I done your advise but it didn`t affect .
I think for this purpuse some changes sould be done in source code of eigen analysis.Is it right?
and perform of this changes is too hard for me as a beginer operator!!!!!!!!!!!!
Thanks for your advise

silvia · Post by **silvia** » Fri May 16, 2008 9:35 am

no, this is not a program issue, it is a modeling issue.