Resilient steel frames installed with self-centering dual-steel buckling-restrained brace

As one type of effective earthquake-resisting structural systems, buckling-restrained braced frames are expected to provide good seismic performance through significant plastic yielding to dissipate earthquake energy. This plastic deformation can cause significant structural damage and residual drift, leading to high retrofitting cost or even demolishment of structures after strong earthquakes. As a result, development of new systems that can not only dissipate seismic energy, but also possess self-centering ability, becomes necessary. This paper makes use of a newly proposed type of self-centering dual-steel buckling-restrained braces (SC-DBRBs). The SC-DBRB consists of a low-yield-point steel and a high strength steel, in which the low-yield-point steel mainly provides energy dissipation ability, and the high strength steel offers self-centering ability and additional energy dissipation ability during strong earthquakes. Compared with a conventional BRB (CBRB) commonly with a typical bilinear constitutive model, the SC-DBRB has a trilinear hysteretic behavior, leading to early re-yielding of the low-yield-point steel during subsequent strain reversals. This early re-yielding mechanism can greatly mitigate residual deformation of the SC-DBRB. In this paper, the constitutive model of the SC-DBRB is first established, and its correlation with main design parameters is also discussed. To demonstrate the self-centering ability of the SC-DBRB and its effect on post-earthquake performance of structures, a series of six-story and nine-story steel frames were numerically investigated using ABAQUS: unbraced frames, CBRB-equipped frames and SC-DBRB-equipped frames. Time history analysis results show that the SC-DBRB can effectively reduce residual drift.