How to define the yield strength in Bouc-Wen uniaxial material ?

[EmadOgail]

Hello,

I am performing a time-history analysis on a single-degree-of-freedom oscillator with non-linear stiffness, using the Bouc-Wen model, to be part of a bigger problem.

When solving this problem analytically using MATLAB, the yield strength can be easily implemented in the model by considering the yield displacement (uy) in the equations.

On the other hand, when modeling this oscillator in OpenSees, the Bouc-Wen uniaxial material does not have a parameter to specify the yield strength.

To overcome this problem, I have scaled the ground motion amplitude by (1/uy). The results are the same as MATLAB but multiplied by (1/uy). So, I divided them by this factor and got the same results.

However, this method is not useful when implementing this oscillator in a bigger problem because the other components are affected by the scaled amplitude.

Is there any solution to specify the yield strength or to solve the problem?

Thanks.