damping curve

ebe79442114 · Post by **ebe79442114** » Mon Oct 27, 2008 11:42 pm

I have shear strain vs damping ratio curve from laboratory. can I get the damping curve to opensees.

pleas, excuse me for my poor english.

bayram_aygun · Post by **bayram_aygun** » Fri Oct 31, 2008 10:05 am

1) You might want to email

Zhaohui Yang (zhyang@ucsd.edu)
Ahmed Elgamal (elgamal@ucsd.edu)

to inquire about this.

2) You can also try to look at the "opensource" soil program DEEPSOIL

<http://cee-zzvy.cee.uiuc.edu/Website/Deepsoil/>

to find out whether there is a way for you to get to "equivalent" Rayleigh damping coefficients from "shear strain vs damping ratio curve". Once you get (if possible) these "equivalent" coefficients you might be able to use them in OpenSees.

Hope this helps a little bit,

ebe79442114 · Post by **ebe79442114** » Sat Nov 01, 2008 3:46 am

Thanks.
I will study it.

ebe79442114 · Post by **ebe79442114** » Sun Nov 09, 2008 9:59 pm

Flush program can take damping V.S shear strain. thus OpenSees also must able to do this.
how you think?

flush:http://nisee.berkeley.edu/elibrary/Text/61000590

pleas excuse me for my poor english.

jaugalde · Post by **jaugalde** » Wed Dec 03, 2008 9:40 pm

I have shear strain vs damping ratio curve from laboratory. can I get the damping curve to opensees.

I don't see anywhere in the manual where you can specify a user defined damping curve. However, you can specify user defined shear modulus reduction curve for the UCSD multi yield soil materials.

For the pressure independent material you can calculate the damping curve implied by your modulus reduction curve as the unloading-reloading is specified by Masing criteria. So, you can fit your damping curve (or probably fit to some degree target modulus reduction and damping curves). Note you will be fitting your target curves over some strain range, you won't get an exact match when the model uses Masing criteria.