Calibration of nonlinear spring for collapse of RC frames

[andrett7]

Dear all,

I'm a little bit confused about the calibration of nonlinear spring for RC members in a frame. I followed the equation proposed by Fardis (2001) and Haselton to calibrate the bilin material of the springs, but if I compare the initial vibration periods of the frame with the same frame without springs the former is more flexible.

Should I modify the initial stiffness of the spring (namely Yield drift) ? The equations of Haselton are still valid for members in a frame?

Thanks in advance,

Andrea

[fmk]

just adding springs unless inf stiff will make structure more flexible .. they tlk about the efects in this paper, though i do not necessarily agree with their soln you can try it.

Zareian, F. and Medina, R. A. (2010). “A practical method for proper modeling of structural damping in inelastic plane structural systems,” Computers & Structures, Vol. 88, 1-2, pp. 45-53.

[andrett7]

Thanks Frank,

I'll read the paper. So in your opinion another possibility is to simply use the parameters coming from the calibration made by Haselton for the inelastic spring and the inertia of the gross section for the elastic member in between?

Thanks again,

Andrea

[fmk]

i haven't read the paper so i have no opinion on it .. i was just explaining why the period is going to change when you through in those springs.

[ghaemiansaeed]

you can add -jntOffsset using secAggregator command