Seismic performance evaluation of buckling-restrained braced RC frames considering stiffness and strength requirements and low-cycle fatigue behaviors

摘要

Buckling-restrained braces (BRBs) have been widely adopted in engineering structures for seismic protection owing to their satisfactory energy-dissipating performance at favorable costs. However, the low-cycle fatigue fracture of BRBs may cause structures to fail in unexpected failure modes under strong earthquakes. Moreover, as the two fundamental parameters of a BRB, strength and stiffness exhibit a matching relationship. In this study, the effect of the core plate geometric construction on the strength and stiffness of a BRB was first quantified. Then, a total of 27 seven-story inverted V-type BRB-reinforced concrete frames (BRB-RCFs) with three story shear ratios p and nine corresponding stiffness ratios k were designed. The seismic responses of the structures considering low-cycle fatigue behavior under 22 far-field ground motions were evaluated, in terms of inter-story drift ratios, BRB cumulative plastic deformation, BRB damage indices, etc. The correlations between the seismic performance indices were analyzed. In addition, the effects of story shear ratios and stiffness ratios on the structural seismic response were assessed, and the optimal design for a BRB core was suggested. The analytical results can provide fundamentals to develop the design approach for BRB components and BRB-RCF systems.