Element with birth and dead

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Jimzhao
Posts: 10
Joined: Sun Dec 27, 2009 8:50 pm
Location: ZheJiang University of Technology

Element with birth and dead

Post by Jimzhao » Mon Feb 22, 2010 6:29 pm

Could you tell me that how to OpenSees consider the elenment with birth and dead capacity? I Want to use Opensees to simulate the construction process of bridge .
Thanks very much!

fmk
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Post by fmk » Tue Feb 23, 2010 10:51 am

when you add/remove nodes, elements, constraints to/from the model the domain is flagged as hacvng changed and the analysis re-initializes itself to take this into account. the state of the other elements in the model does not change.

when adding elements most (NOT ALLl) elements look at current nodal displacements and if non-zero, store these as initial displacements .. all subsequent state determination is done with these initial nodal displacements subtracted from the current ones.

when removing an element, the resisting forces from the element at the node are obviously removed and if there were any this makes the node unbalanced for the next analysis step. note if you remove elements you cannot leave dangling nodes.

songlianglong
Posts: 9
Joined: Sun Jan 24, 2010 7:41 pm
Location: southeast university

problem about opensees

Post by songlianglong » Mon May 17, 2010 10:41 pm

[quote="fmk"]when you add/remove nodes, elements, constraints to/from the model the domain is flagged as hacvng changed and the analysis re-initializes itself to take this into account. the state of the other elements in the model does not change.

when adding elements most (NOT ALLl) elements look at current nodal displacements and if non-zero, store these as initial displacements ..

just how to "store these as initial displacements .. "?
please,please!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:shock:

fmk
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Post by fmk » Tue May 18, 2010 9:56 am

they are stored in the elements .. have a look at the source code ..

[url]
http://opensees.berkeley.edu/cgi-bin/cv ... C/element/
[/url]

songlianglong
Posts: 9
Joined: Sun Jan 24, 2010 7:41 pm
Location: southeast university

add a new element

Post by songlianglong » Tue May 18, 2010 4:17 pm

[quote="fmk"]they are stored in the elements .. have a look at the source code ..

[url]
http://opensees.berkeley.edu/cgi-bin/cv ... C/element/
[/url][/quote]

i am so frustrated. i have not learned c++ so i can not understand the source code?
if i want to add a new element to the domain during a analysis,must l use the code written by c++?

Jimzhao
Posts: 10
Joined: Sun Dec 27, 2009 8:50 pm
Location: ZheJiang University of Technology

Re:

Post by Jimzhao » Thu Apr 28, 2011 10:51 pm

fmk wrote:
> when you add/remove nodes, elements, constraints to/from the model the
> domain is flagged as hacvng changed and the analysis re-initializes itself
> to take this into account. the state of the other elements in the model
> does not change.
>
> when adding elements most (NOT ALLl) elements look at current nodal
> displacements and if non-zero, store these as initial displacements .. all
> subsequent state determination is done with these initial nodal
> displacements subtracted from the current ones.
>
> when removing an element, the resisting forces from the element at the node
> are obviously removed and if there were any this makes the node unbalanced
> for the next analysis step. note if you remove elements you cannot leave
> dangling nodes.

thanks very much! a long time leaving!

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