Base Shear vs. Top Displacement Response in LRB System (Bouc-Wen Model)

[Oleg Dzampaev]

Dear Сolleagues,

I have developed a model of a four-story reinforced concrete building with a soft story, base-isolated using a Lead Rubber Bearing system.

I am trying to plot the Base Shear versus Top Displacement curve. However, as shown in the figure below, my final result does not match the typical hysteretic behavior of the Bouc-Wen model presented in the SeismoSoft documentation (https://help.seismosoft.com/seismostruc ... ?agt=index).


How can I justify the correctness of my results, and why does the response not follow the expected bilinear shape?

Best regards,
Oleg Dzampaev

[Oleg Dzampaev]

P.S. For your reference, the isolator properties used in the model are shown in the figure below:

Please also note that I used the Total Support Force to represent the Base Shear in this plot.

[seismosoft]

The smooth curve is derived under normal loading conditions, e.g. a smooth force-displacement curve, constant axial loads and no dynamic response.
However, indeed the curve seems to be a bit strange, and most likely this is related to the overall dynamic response of the entire structure. Probably you will need to discuss the details of your model with your supervisor.
Seismosoft Support

[Oleg Dzampaev]

Thank you for your reply.

Could you perhaps point me to some example models that incorporate seismic isolation, purely for illustration and to better understand the typical response?

[seismosoft]

In our Sample models database, there are simpler models that display the use of isolators (see the SeismoStruct support page on our website).
Unfortunately, larger and more complex models of isolated buildings are proprietary to their respective developers and therefore cannot be distributed.
Seismosoft Support