Hysteretic performance of all-steel assembled double-cores buckling-restrained braces using Q195 low-yield core

Abstract

This paper focuses on the hysteretic behavior of a proposed all-steel assembled double-cores buckling-restrained braces (DCBRB). The DCBRB employs an I-shaped steel and two channels to resist the global instability of the brace and hence to force the double-cores into high-order buckling mode for the purpose of energy dissipation. Six DCBRB specimens were fabricated, where both Q195 low-yield core and Q235B core were concerned for comparison. The quasi-static cyclic loading was conducted on the DCBRB specimens to investigate the failure modes, as well as the hysteretic behavior from different perspectives, such as hysteretic curves, skeleton curves, compressive strength adjustment factor, energy dissipation capacity and plastic deformation performance. The experimental results demonstrate that the insufficient constraining of the external restraining member could cause the global instability of the buckling-restrained braces. The specimens exhibited great and stable hysteretic responses until the axial strains of cores researched 1.5%. Finally, the cumulative plastic deformation capacities were greater than 300 for all specimens. The finite element models were established to further investigate the influence of constraint ratio and core's width-to-thickness ratio on the hysteretic behavior of the DCBRBs. The numerical results reveal that better global stability is expected to be obtained with a larger constraint ratio ζ, and the limit value of ζ avoiding the global buckling almost increases linearly with the increase of core's width-to-thickness ratio.