Sliding gusset connections for improved seismic performance of BRB-RC frame: Damage-control design and subassemblage tests

Although buckling-restrained braces (BRBs) have been widely adopted to improve the seismic performance of RC frames (RCFs), their performance was often limited by premature failure of the RCF joint or the gusset connection in the braced bay due to significant frame-to-gusset interaction induced by conventional gusset connections. Previous studies by the authors have validated the effectiveness of sliding mechanism mitigating such an interaction for steel moment-resisting frames, in which relative sliding at the frame-to-gusset interfaces was allowed by providing low-frictional layers. In this study, two innovative sliding gusset connections, featured by sliding anchor plate (SA) and sliding gusset plate (SG) configurations, respectively, are proposed for the BRB-RCF to mitigate the negative frame-to-gusset interaction. A damage-control design procedure is presented to prevent undesirable failure of the BRB-RCF joint. Cyclic tests of five BRB-RCF subassemblages with different connection details were conducted to evaluate the reasonable sliding mechanism and the effectiveness of the design pro-cedure. Structural behaviors of the RCFs, connections and BRBs are compared with the case adopting conven-tional gusset connection. Test results showed that the SA connection is more effective than the SG connection mitigating the frame action effects, including reducing the shear force and energy dissipation demands on the RCFs, shifting the crack pattern of RCF from shear to flexural mode, and reducing the gusset plate stress, but has no significant influence on the overall hysteresis and energy dissipation capacity of BRBs. The damage-control design procedure is effective ensuring reliable BRB force transfer to the RCF joint and mitigating the normal interaction at the connecting interfaces. Future research needs for improved structural performance and design of the SA connection are provided finally.

Automated summary

In this study, two innovative sliding gusset connections are proposed to mitigate the negative frame-to-gusset interaction in buckling-restrained brace (BRB) reinforced concrete frames (RCFs). A damage-control design procedure is presented to prevent undesirable failure of the BRB-RCF joint. Cyclic tests of five BRB-RCF subassemblages were conducted to evaluate the sliding mechanism and the effectiveness of the design procedure.