The seismic behavior of Conventional Bracing System equipped with a Iron Based Shape Memory Alloy

Buckling restrained braces have been shown to exhibit favorable energy dissipating characteristics in steel structures during an earthquake and are therefore widely used in passive control of structures. However, they face the problem that they do not return to their original shape upon unloading, and consequently, the structure experiences large permanent deformations after the earthquake which usually makes the structure impossible or uneconomical to repair. In recent years, to solve this problem, researchers have used Iron-based shape memory alloys which have two essential properties of superelasticity and shape memory behavior. These alloys have been considered due to their high energy dissipation capacity, their ability to withstand large strains, recentering and not leaving permanent deformations upon unloading, and their much lower cost than other shape memory alloys. In this research, the seismic behavior of three-story structures braced with buckling restrained braces, iron-based shape memory alloy, and nitinol shape memory alloy, which is one of the most famous shape memory alloys, is investigated. Modeling and Nonlinear dynamic analysis for these structures have been performed in Seismostruct software. Maximum displacements, residual strains, and force-displacement diagrams of these structures have been studied due to the application of different accelerometers of large earthquakes of recent years with different intensities. The results of this study show that braced structures with Iron-based shape memory alloys experience more maximum displacements than Buckling restrained braces, although unlike BRBF they do not leave any permanent displacement. Also, these structures undergo fewer maximum displacements and permanent displacements compared to nitinol-braced structures, and in general, show better performance.