define negative stiffness

[Ahil_Anand]

In Takeda curve, 5 parameter should be define. I have a section with Mu lower than My, but with more displacement. It means that the slope of the behaviour curve is negative after yeilding. Therefor, Ku is negative and the ratio between Ky and Ku is also negative, but I can define a negative value for this parameter (third parameter in Takeda curve). What should I do in this case?

[seismosoft]

Hi Ahil_Anand,
Unfortunately, you cannot define a negative stiffness between My and Mu using the Takeda or any other multi-linear curve in SeismoStruct.
If you use a zero post-yield stiffness, is the loss of accuracy significant?

Seismosoft Support