Investigation on the interaction between BRBs and the RC frame in BRB-RCF systems

Abstract

Due to the different mechanical behavior of buckling-restrained braces (BRB) and reinforced concrete frames (RCF), their coupled work in dual structural systems (BRB-RCFs) is complicated, especially their earthquake responses. A series of structures with different numbers of stories and different story shear ratios equipped with BRBs were designed and tested in simulation. Static nonlinear pushover analysis and cyclic loading were simulated to investigate the interaction between BRBs and RCFs. The capacity curves, the story distributions of shear force, axial forces on the columns, strength and stiffness, lateral displacement, interstory drift ratios and hysteresis behavior were evaluated. Adding BRBs in a RCF was found to alter the story distribution of shear force and to significantly increase the axial demands on RC columns in BRB-braced bays. The yield strength, initial elastic stiffness and energy dissipation capacity of BRB-RCF structures are all greater than the sum of the contributions from the braces and the frames independently. That synergistic interaction cannot be ignored in design.