Analytical and experimental studies on buckling-restrained brace with gap-supported tendon protection. (January 2020) - Wang, Chun-Lin
Abstract: This paper proposes a new brace called TP-BRB, composed of a conventional buckling-restrained brace (BRB) with a gap-supported tendon protection (TP) in parallel. The gap-supported tendon protection remains inactive before the deformation of TP-BRB reaches a threshold value, while obtaining a high axial stiffness after the threshold value is exceeded. Under strong earthquake, the TP-BRB is expected to provide structures with effective energy dissipation capacity and mitigate the risks of global collapse caused by low post-yield stiffness of the conventional BRB. As the earliest part of the research on the TP-BRB, this paper firstly presents both the stiffness characteristics of the hysteretic curve and a theoretical formula of residual deformation. Secondly, a quasi-static test is conducted, the results of which illustrate that TP-BRB shows a stable hysteretic behavior, a skeleton curve with significant tri-linear characteristic, and a smaller residual deformation than a conventional BRB. Finally, parametric studies based on numerical models show that, with the reduction of the threshold value ( u 0 ) and the increase of the ratio ( γ ) between the axial stiffness of BRB and gap-supported tendon protection, both the residual deformation and the equivalent damping ratio of TP-BRB decrease, but the secant stiffness of TP-BRB increases. Highlights: A new brace is composed of an inner buckling-restrained brace and an external gap-supported tendon protection. Theoretical analyses about stiffness characteristics and residual deformation of the new brace were detailed. Test results shows it has stable hysteretic behavior, tri-linear characteristics and small residual deformation. Hysteretic behaviors of brace are affected by the axial stiffness of its components and initial gap.