Constraint Equations

burnningcat · Post by **burnningcat** » Thu Oct 01, 2009 2:06 am

Dear Sir,

Would anyone teach me how to introduce a constraint equation in OpenSees? For example, how to make DOF3=DOF1+DOF2? I mean how to make the degree of fredom 3 equal to the sum of degree of freedom of 1 and 2?

Thank you for your help!

silvia · Post by **silvia** » Thu Oct 01, 2009 7:45 am

if they are the same dof you can use trusses in series.

Post by **fmk** » Thu Oct 01, 2009 4:07 pm

you would need to write some C++ code to do that

burnningcat · Post by **burnningcat** » Fri Oct 02, 2009 6:53 am

Dear fmk,

Thank you for your reply, but would you please tell me if there is any example to write the constraint equaitons?(like the implementation of a new element and the material). Or would you please tell me from which file I can start?

I know this question is quite difficult to explain, but I really don't know how to start. Thank you!

Post by **fmk** » Fri Oct 02, 2009 11:23 am

you need to construct an MP_Constraint object .. have a look at the equalDOF command in OpenSees/SRC/modelbuilder/tcl/TclModelbuilder.cpp for an example.