Residual displacement/permanent deformation

04-Unexpected behaviour/errors
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Residual displacement/permanent deformation

Post by zhanggqi »

I am running a time history analysis of a regular RC column. I scaled the acceleration history loading to a very high level. The max drift during the earthquake is about 5%. From hysteretic curves, I can see a lot of yielding and energy dissipation.
However, when I look at the structural displacement at the end of the analysis, the residual displacement/permanent deformation is still very small. Does this look normal?
I saved the seismostruct file and two result screenshots here ... EWtAa?dl=0

Any suggestions are appreciated.

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Re: Residual displacement/permanent deformation

Post by seismosoft »

Hello Zhanggqi,

A permanent drift of 2.5cm in 6m is a drift of 0.4%. This is by no means small. It implies a rotation of 180*atan(2.5/600)=0.75 degrees, i.e. almost 1 degree. This is not small, epsecially considering that the section of the pier is highly reinforced with large confinement (16mm/10 spiral hoops).
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Re: Residual displacement/permanent deformation

Post by huffte »

I will add that residual displacement can vary from almost zero to a value slightly less than the maximum displacement, depending on the ductility level, post-yield stiffness, the period of the structure, degradation, and the ground motion, among other parameters. You cannot base a residual displacement estimate on a single ground motion. You might find the following interesting: ... scillators
Tim Huff

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