The hysteresis loop of SMA elements looks like a flag. Such a hysteresis has the benefit of some energy dissipation along with minimal residual deformations upon removal of the load, hence mostly preferred for re-centering devices.
Figure 1. Idealized stress-strain curve of Superelastic SMAs
It is possible to simulate superelastic SMA behavior in SAP2000 using multiple link elements as described in Andrawes, B., and DesRoches, R. (2005).“Unseating prevention for multiple frame bridges using superelastic devices.”Smart Mater. Struct.,14(3), S60–S67.
Figure 2. Schematic diagram of superelastic SMA model developed using two links elements element from Adrawes and DesRoches 2005
Using a multilinear elastic and multilinear plastic link in parallel we get the following flag shaped force-deformation behavior:
Figure 3. Force-Deformation curve. Example of superelastic SMA modeled using two links elements
Figure 4. Multilinear Elastic Link. Example of superelastic SMA modeled using two links elements
Figure 4. Multilinear Plastic Link. Example of superelastic SMA modeled using two links elements