Influence of the SMA Constitutive Model on the Response of Structures

Strong earthquakes may impose significant displacements in structures, which can result in excessive displacements at structural joints. Previous numerical studies have shown that the recentring capability of shape memory alloys (SMA) can be applied to limit joint openings and maximum longitudinal displacements. However, these studies do not focus on the influence of the SMA constitutive model adopted on the estimated displacements. A sensitivity analysis was performed using simplified two-degree-of-freedom models, which represent two-frame reinforced concrete bridges with various ratios of natural periods of vibration, connected by SMA bars. These models were implemented in a MATLAB based program for nonlinear dynamic analysis. The obtained results show that the relative displacements are more sensitive to the SMA model than the absolute displacements.