Rayleigh damping problems

[Motaei]

fmckenna wrote:
> betaKcomm will use the stiffness matrix at the last time step .. as for
> modal
>
> It should be in the version available for download. Not all solvers have
> been modified to work with it, all but the sparse should work, and it does
> not work yet in parallel.
>
> there are 2 commands:
> modalDamping $ratio
> modalDampngQ $ratio
>
> the latter ignores adding any part of C to the tangent matrix. the commmand
> uses the existing eigenvectors, so the eigenvector command must have been
> issued first. a wipe currently does not remove the factor, so if in a
> script you want to play with modal and then rayleigh you need to call the
> modal command with a 0 ratio before the analyze. you can issue a rayleigh
> command with he modal to damp out high frequency modes that are not covered
> as Prof. Powell recomends in the PERFORM manual. The issue never popped up
> (in the responses i have looked at) so don't know how much of an issue it
> is as at least for the disp response the response is governed by the
> fundamental modes.
>
> i have not finished with it yet, there are things i wanted to add like the
> ability to have different ratio's for different modes and get it working in
> paralllel. if you notice anything amiss let me know as i am still making
> sure it works for all cases before the commands make it to the command
> manual.

Dear fmckenna
I'm trying to use modalDamping command recommended by prof. Chopra
but apparently the command does not work with some of the integrators provided in OpenSees
I've used modalDamping command with central difference, generalized-alpha and KRAlphaExplicit integrators and the following error appears when I run the code:
IncrementalIntegrator: :getVel<> - not implemented for this integrator
Is there any way that I can use the modal command with the mentioned integrators?
and if there is, can you please provide me with a reference to do so.
Thanks for your time

[fmk]

not till the code is changed and released. if you want to build your own version you could modify said integators to return the vel they are computing.