Modeling of Concrete Shear Walls Retrofitted with SMA Tension Braces

A recently developed Shape Memory Alloy (SMA) model is implemented to simulate the seismic retrofit of squat concrete shear walls with novel tension-only SMA braces. The model follows a tri-linear envelope that captures the flag-shaped behavior of superelastic SMAs and the accumulation of plastic straining at large strains. The response of the SMA braces is modeled with tension-only truss elements that are assigned the stress-strain parameters obtained from bare brace testing. The results provide satisfactory predictions of strength, drift, damage, energy, and displacement recovery. The effect of axial load and size of the SMA on the performance of the retrofitted walls are assessed through a parametric study.