Advtantage of Modified IMK curve of BWBN Curve

[bibhasp]

In SeismoStruct Bouc-Wen-Baber-Noori(BWBN) hysteresis curve is not available, whereas this is available in OpenSEES. What is the advantage of Modified IMK hysteresis curves over BWBN curves?
Modified IMK curves are piecewise linear, whereas BWBN curves are SMOOTH, which I think more realistic model for hysteresis. Please explain.

[huffte]

As to the advantages and disadvantages of each, I cannot fully attest. However, I believe you will find that the 'Smooth' model in SeismoStruct effectively corresponds to the BWBN model to which you refer. So both options are actually available in SeismoStruct. Best of luck in your work.

[bibhasp]

Thank you huffte.