Uniaxial quasi-static cyclic tests on the hysteretic behavior of a novel type of all-steel buckling-restrained brace

To minimize the residual welding deformation in the steel core of cruciform cross-section of conventional buckling-restrained braces (BRBs), a novel type of all-steel BRB, called Angle BRB (ABRB), has been developed. The steel core of ABRB consists of four angle steels of equal sides to form a non-welding cruciform yielding cross-section, and the outer restraint is composed of two angle steels of equal sides welded longitudinally to form a square hollow cross-section. Uniaxial quasi-static cyclic tests for four ABRB specimens were carried out to investigate the hysteretic behavior, in which the effects of boundary condition, construction of rotation restraint at the brace end, construction at the core projection, loading length, etc. are considered. The relative initial geometric imperfection in the yielding segment of the steel core specimens was measured before the tests, which shows that such imperfection can be well controlled within the limit of 1/1000. The test results indicate that the ABRB specimens with rigid connection exhibit better hysteretic performance than other specimens. The local compression-flexure failure mode is inclined to occur at the core projection for the ABRB specimens with pin connections and without rotation restraint at the brace end. The local compression-flexure failure occurs earlier when the loading length increases, which can be safely prevented by setting rotation restraint at the brace end. The seismic behavior of the ABRB specimens are analyzed and it is revealed that the ABRB specimens with rational constructions exhibit plump and stable hysteretic performance before failure, indicating good ductility and satisfactory cumulative hysteretic energy dissipation capacity, which shows that ABRB can serve as an effective passive energy dissipation device for structures.