Lead Rubber Bearing Properties

Question:

I am trying to understand MIDAS input for the Lead Rubber Bearing Properties.
In the attached screen shot, in the Linear Properties the stiffness is defined as 336.1 tonf/m, then in the Nonlinear properties the stiffness is defined as 1099 tonf/m. How come the stiffness differs in both cases? as it changes from 336.1 to 1099? shouldn't the stifnesses be the same?? please explain in details with examples please






Answer:

The linear effective stiffness of LRB is used to compute the fundamental natural period of a base isolated bridge. It is determined as below. Therefore, the linear effective stiffness can be different from the initial stiffness of nonlinear properties.



You can refer to the articles below for more information.
http://www.iitk.ac.in/nicee/wcee/article/13_3332.pdf
http://www.iitk.ac.in/nicee/wcee/article/WCEE2012_5756.pdf

Regards,
DK Lee
Creation date: 5/28/2018 1:32 AM (dklee@midasit.com)      Updated: 5/28/2018 11:03 AM (dklee@midasit.com)
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