Cyclic tests of assembled self-centering buckling-restrained braces with pre-compressed disc springs

Abstract

The assembled self-centering buckling-restrained brace (SCBRB), consisting of a novel type self-centering (SC) part and a buckling-restrained brace (BRB) part that work in parallel under cyclic loads, was constructed to reduce residual deformation of the brace and to provide additional energy dissipation capacity by the compressed disc springs in the SC part. Tests were carried out to mainly investigate the effects of constructional details, as well as the self-centering ratio of pre-compressed force of SC part to compression strength of BRB part at a specific story drift, on the hysteretic behavior of SCBRBs. The tests revealed that, compared with the BRB, residual deformation of the SCBRBs was greatly reduced and that the residual deformation almost disappeared when the self-centering ratio, under story drifts of 2%, is larger than 1.0. For each SCBRB, axial strength is mainly from the SC part and energy dissipation is mostly from the BRB part within the drifts of 3%. With increase of the self-centering ratios under the same pre-compressed force, both the residual deformation of SCBRB and the energy dissipation of BRB part decreased. Meanwhile, energy dissipated by the SC part is about 18–25% of total energy of SCBRBs under the drifts of 2%, indicating that the SC part can provide not only resilience but also energy dissipation. Tension fracture of encased steel plate brace in SCBRBs occurred and the other assembled components kept intact after tests, facilitating repair of encased brace and reuse of intact components. On the whole, the SC part, the BRB part and SCBRBs exhibited stable hysteretic behavior and bilinear backbone curves. Good elastic deformability of the SC part ensured remaining capacity of SCBRB after tensile failure of BRB.