singleFPBearing kInit value

[hgp]

Hi OpenSees community,

I'm curious if it's possible to specify the initial stiffness "kInit" of the singleFPBearing as F_y/u_y rather than the current mu/u_y.

I currently have kInit as defined via the wiki page: mu/u_y. However, I am running into strange results where bearings that take double the load (i.e. inner columns) have half as much initial stiffness as the outer columns. Plotting the hysteresis loop below, I would expect for all loops to have the same stiffness. But as you can see, some loops have inconsistent initial slopes.

https://drive.google.com/file/d/1IRE95B ... sp=sharing

Could this be another issue than kInit? My loads are currently defined as a distributed line load onto the frame here: https://opensees.berkeley.edu/wiki/inde ... me_Example, except isolated.

Thanks for your help in advance.