modeling SMA braces in 6story steel frame

[roshen.rj]

Indeed the scb response curve is appropriate for the link element. I thought that you meant that you were trying to use the SMA material model with the link element. Regarding the convergence problems that you face, carry out a search for 'convergence', you will find numerous posts. Specifically for the link element, make sure that all DOFs are fixed. An eigenvalue analysis might give you valuable insignt
Seismosoft Support

Yes, all the DOFs have been fixed except the DOF to describe the SCB response. I have run an eigen value analysis already and obtain 10 eigenvalues. Even the pushover seems to be working fine

[seismosoft]

Carry out a search in the form for convergence problems. There is also a section in the User's Manual on how to fix such convergence problems.
Have a look at the Convergence Details page in the post processor, you might get valuable information.
Seismosoft Support