عنوان مقاله [English]
Conventional seismic resistant systems generally dissipate earthquake energy through the plastic deformation of structural elements. These systems suffer high residual displacements increasing the cost of repair or even necessitate reconstruction of the building. In recent years, researchers have focused on Self-centering lateral load resisting systems due to earthquake energy absorption in replaceable elements and reduced residual displacement. One of the recent types of these systems is self-centering buckling restrained brace system. In this study, the hysteretic performance of a 9-story structure with a dual steel moment resisting frame system equipped with a self-centering buckling restrained 2-story-x-brace is investigated.
At first, the parameters affecting the performance of the bracing were specified. These parameters included the yielding stress of the bracing core, the ratio of cable pre-stressing force to the cable yielding force, and the ratio of cable to core area. For the yielding stress of the core two values of 240 and 360 MPa, for the pre-stressing ratio five values from 0.1 to 0.5, and for the area ratio, seven values of 0, 0.25, 0.5, 1, 2.5, 5 and infinity were selected. So therefore, a total of 62 models of 9-story structures with dual steel moment resisting frame system equipped with self-centering buckling restrained brace were constructed. The models were analyzed using OpenSEES finite element software. Performing nonlinear analyses under cyclic loading, the hysteresis diagrams were obtained. The optimal design for these models was performed considering residual displacement and energy absorption as two main parameters. Finally, the performance of the optimized structure equipped with self-centering buckling restrained brace was compared with the structure equipped with ordinary buckling restrained brace. According to the results, the optimized self-centering structure may reduce 60% of the residual displacement while its energy absorption drops by only 37%. Generally, the results indicated the prominence of the optimized self-centering structure.