Development and experimental study of a new dual tee-section buckling-restrained brace

Abstract

A new buckling-restrained brace with a dual-tee core (DTBRB) was proposed to reduce the out-of-plane buckling of the core, improve the fatigue property, and increase the bearing capacity of the brace. The restraining part included the assembled restraining plates, the fillers, and the assembled channel steels. The core consisted of two T-sections separated from each other and placed symmetrically. The outer part of the core was utterly constrained by the assembled restraining plates, while the inner edge part was only restrained by the assembled channel steel, and the web was unrestrained. All DTBRB specimens performed excellent hysteretic behavior, and no obvious degradation of stiffness and bearing capacity was observed before the failure. The flange and web of DTBRB had multi-wave buckling deformation. Compared with the buckling-restrained brace with the rectangular section core, setting the web on the rectangular steel plate to form a tee-section core was an available approach to decrease the out-of-plane buckling of the flange. The web with a small height-to-thickness ratio had no obvious out-of-plane buckling and could effectively restrain the out-of-plane deformation of the flange. The web with a large height-to-thickness ratio had plastic buckling deformation, causing torsional deformation of the flange. The design formula to prevent the out-of-plane buckling of the web was established. The design method of the dual-tee core of DTBRB was proposed based on the suggestion of the partially buckling-restrained brace with a steel plate core.