Pushover curve when only non-linearity is from Link elements

04-Unexpected behaviour/errors
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mafmoh123
Posts: 3
Joined: 13 Feb 2018, 10:14

Pushover curve when only non-linearity is from Link elements

Post by mafmoh123 »

Hello,

I have modelled a prefabricated modular building in seismostruct. In this study, my assumption is that the Prefabricated Modules are rigid bodies and the conncetions between these modules are flexible. So, I have modelled the Modules using elfrm element and then added separate rigid diaphragms in XZ plane so that the Modules will behave as rigid bodies. I have used Trilinear symmetric link element to represent the Non-linear connection between the Modules.(Its' like rigid squares connected by links at four corners)

The model is perfectly fine in everything like the period(Eigenvalue analysis), modal mass participation factors and it runs very well in static and Non-linear time history analysis as well.

But my problem is, when i conducted a pushover analysis, it gives me a straight line pushover curve. It seems that neither Non-linearity of the link is taken into account, Nor the geometric Non-linearity get's activated. Could anyone of you please clarify me the reason? is it that, seismostructs Geometric Non-Linearity gets activated only if the frames are non-linear? is it not something natural when the links displace and the Geometric Non-linearity occurs? why am i seeing a linear pushover curve?

https://www.dropbox.com/s/2ilzzwzua5i3o ... n.srf?dl=0 I have my model uploaded here. any comments appreciated, Thanks in advance
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seismosoft
Posts: 1184
Joined: 06 Jul 2007, 04:55

Re: Pushover curve when only non-linearity is from Link elem

Post by seismosoft »

The geometric nonlinearity is also accounted for in link elements. However it is generally visible only with very large, which is a very rare case for link deformatiions. Furthermore, can it be that the deformation in the link element is below the yield displacement, so that you get a linear elastic behaviour?
In general a pushover curve can have a parabolic-like shape if you have nonlinearities activated in your structure.
Finally, note that you have attached the results rather than the input file, hence we could not view your model.
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