eigen analysis

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rob
Posts: 1
Joined: Tue May 24, 2005 5:39 am

eigen analysis

Post by rob » Tue May 24, 2005 6:35 am

Hi,
I'm trying to have an adaptive pushover imposing a displacement vector instead of a force one and modelling it at each step combining the results of eigen analysis but this seems to be impossible. In particular after the imposition of displacements with sp command opensees seems not to be able to calculate eigenvalues.
Any help or suggestion?
Thanks

fmk
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Post by fmk » Tue May 24, 2005 9:22 am

the displacements you have imposed are implemented using single point
constraints .. the boundary conditions are therefore fixed .. when you do
the eigen analysis these are not considered free degrees-of-freedom.

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