SEISMIC PERFORMANCE OF STRUCTURAL SYSTEMS EQUIPPED WITH BUCKLING-RESTRAINED BRACES

Buckling-restrained braces (BRBs) are often employed for the seismic retrofit of existing buildings and the design of new structures, given their significant contribution in terms of stiffness and added damping. However, BRBs are characterized by a low lateral post-elastic stiffness, leading to excessive residual deformations that may compromise reparability. Moreover, accumulation of plastic deformations in the BRBs may compromise the capability of withstanding multiple earthquakes and aftershocks. The objective of this paper is to provide insight into the performance and residual capacity of dual systems made of BRB frames coupled with moment-resisting frames, through a simplified single-degree-of-freedom model. A non-dimensional formulation of the equation of motion is introduced, the statistic of the normalized peak, residual displacements and cumulated ductility of the system is evaluated for a set of ground motion records. Different values of the BRB target maximum ductility and coupled frame properties are considered.