Seismosoft | Earthquake Engineering Solutions

Hello everybody!
I'm writing because I have some problems with a Seismostruct 2016 model by performing incremental dynamic analyses. I modeled a steel moment resisting frame with leaning columns accounting for second order effects by means of force based elements.

The model is avaliable at this link :
https://we.tl/L0jQ9v46UW

After a number of steps, nodal equilibrium is not verified and columns go in plastic range while beam sections remain in elastic range. When I perform the push-over analysis one other behaviour is shown. In particular, the frame show a quite global mechanism. Is there anybody who can explain me what is wrong in my model?
Thank you very much.

Hi eppy,

The earthquake record that you are applying is rich in high frequency content and it is very strong.
It is not unreasonable to have significant higher order effects and to expect that the structure will not show a smooth behaviour as described in a pushover analysis, where the structural behaviour is assumed to follow the 1st mode.
You can check about higher mode effect both with the deformed viewer and by plotting the nodal deformations at each floor (e.g. 31-1, 21-1 and 11-1)

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