A computationally efficient nonlinear model was developed and implemented in the OpenSees
software platform (Mazzoni et al. 2013) to simulate the cyclic behavior of the SC-BRB. The
hysteretic SMA material model developed by Taftali (2007) was modified to better capture
features of the behavior critical for loss of restoring force in self-centering systems using SMA.
The Taftali (2007) model was based on six parameters (see Figure 4a) including modulus of
elasticity for the austenite phase, E SMA , forward transformation stress (austenite to martensite),
F s
AS , secondary slope during transformation, R s , strain at which the transformation to martensite is
complete, d f
AS , modulus of elasticity for the fully transformed martensite, R m , and a reverse
transformation stress (martensite to austenite), F f
SA .