Constant ductility spectra

[nimish07]

Dear all,

I am trying to get inelastic constant ductility spectra for some accelerograms. It always is the case, that the ductility response history and elastic response history differ in the end of the response.

ie my elastic history returns to zero in the end, while the ductile response hovers at a mean value of 50cm . The ending baselines of elastic and ductile are different.

what is the interpretation of this behavior and are the results correct for using in analysis?

[huffte]

Hi nimish07. The response you describe, if I understand your statements correctly, is to be expected. For the non-linear behavior there is always the possibility of some residual displacement in the system. You should also look at the options in the settings - particularly the post-yield hardening ratio which you are using. The smaller the post-yield hardening ratio, the greater the chance of a larger residual displacement it would seem, though I cannot say that this is strictly the case. Make certain that the value being used is the one you wish to analyze.