Self-centering hybrid moment braced frame: Stiffness control and the self-centering acceleration adverse effect

The self-centering brace (SCB) generally exhibits higher initial stiffness than the buckling-restrained brace (BRB), which has great effects on structural performance. In this work, a stiffness control SCB (S-SCB) is proposed to overcome the difficult adjustment of the initial stiffness of the existing SCB. Via the simulation of the S-SCB, it is found that a higher initial stiffness increases the energy dissipation capacity and has no influence on the residual deformation. Four 9-story S-SCB frames (S-SCBFs) with different stiffnesses are simulated, and the influences of the energy dissipation capacity and intensity on the structural response are also considered. It is found that the increase of the initial stiffness can reduce the displacement response, but the serious amplification of the peak absolute floor acceleration (PAA) appears on the middle or lower floors, namely the self-centering adverse effect (SAE). The SAE can be reduced by the lower initial stiffness, high activated stiffness, and greater energy dissipation capacity of the S-SCB. An assessment method including two indices is proposed to describe the degree of acceleration amplification and the floor distribution characteristics. The indices of the S-SCBF are found to exhibit significantly different characteristics from those of the BRB frame (BRBF) and the moment-resisting frame (MRF). The maximum PAA of the S-SCBF is found to be 1.5 times less than that of the BRBF with the same skeleton curve. The feasibility of the acceleration assessment method is verified by a set of frames with 4-, 8-, and 16-story.