Element with birth and dead

[Jimzhao]

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]

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]

[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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[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]

[songlianglong]

[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]

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!