Development and experimental validation of an assembled steel double-stage yield buckling restrained brace

A novel assembled steel double-stage yield buckling restrained brace (DYB) was experimentally studied. The DYB core plate comprises one small core plate and one large core plate connected in series. The deformation capacity of the small core plate is restricted by a stopper mechanism. The deformation of the DYB is first concentrated at the small core plate and then shifted to the large core plate once the stopper mechanism is triggered, resulting in double-stage yield behavior of the DYB. Three specimens were fabricated with core plates of different size to study the main influencing factors in the design of DYBs. Quasi-static tests were conducted. Results from a comprehensive experimental study demonstrate that the DYB has a ductile, stable, and repeatable hysteretic behavior. It is a reliable and practical alternative to conventional framing systems in that it can enhance the earthquake resistance of existing and new structures and provide the rigidity needed to satisfy structural drift limits while delivering a stable and substantial energy absorption capacity. The proposed hysteretic model of the DYB was calibrated with the test results, showing good agreement and the capacity to capture characteristic points of hysteresis curves.