Hysteretic behavior and resilience analysis of a new self-centering buckling restrained braces

Abstract

The self-centering buckling restrained braces (SC-BRBs) are capable of dissipating energy through BRBs elements during seismic events and restoring to their initial positions after the earthquake, thus reducing residual deformations in structures. The traditional design of the SC-BRBs has a complex structure with dual/three steel load transfer tubes and prestressed tendons anchored by steel end plates as a prestressing system. The complexity of these structures and the possibility of errors in machining dimensions and interactions between components can result in uncertainties of the mechanical behavior of the traditional SC-BRBs. As a consequence, a new design has been developed that uses the brace component as the inner load transfer tube for improved stability and load transfer capabilities in this paper. The structural features and mechanics of the new SC-BRB are first described. Then, to examine the performance of new SC-BRB, a quasi-static cyclic loading test was conducted on one scaled model specimen. The results showed that the new SC-BRB exhibited a consistent flag-shaped hysteretic response, with maximum residual strain of 0.15% within the target design drift of 2%. Nonlinear finite element analyses using ABAQUS were conducted to examine the influence of initial prestress magnitude and properties of prestressing tendon materials on the performance of the new SC-BRBs. The findings indicate that pretension is crucial for full self-centering capabilities of the new SC-BRB. When pretension exceeds the yield bearing capacity of the BRB core, it results in full self-centering and eliminates residual deformations. Additionally, the elastic elongation of the prestressing tendon material determines the deformation capacity of the new SC-BRB, while the elastic modulus of the material affects its post-yield stiffness.