Experimental and numerical study of buckling-restrained braces configured with out-of-plane eccentricity under cyclic loading

This study focuses on variations in the hysteretic behavior of buckling-restrained braces (BRBs) configured with or without out-of-plane eccentricity under cyclic loading. Quasi-static experiments and numerical simulations were carried out on concentrically and eccentrically loaded BRB specimens to investigate the mechanical properties, energy dissipation performance, stress distribution, and high-order deformation pattern. The experimental and numerical results showed that compared to the concentrically loaded BRBs, the stiffness, yield force, cumulated plastic ductility (CPD) coefficient, equivalent viscous damping coefficient and energy dissipation decreased, and the yield displacement and compression strength adjustment factor increased for the eccentrically loaded BRBs. With the existence of the out-of-plane eccentricity, the initial yield position changes from the yield segment to the junction between the yield segment and transition segment under a tensile load, while the initial high-order buckling pattern changes from a first-order C-shape to a second-order S-shape under a compressive load.