Seismic design and subassemblage tests of buckling-restrained braced RC frames with shear connector gusset connections

Abstract

As a high-performance hysteretic damper, buckling-restrained braces (BRBs) can significantly improve the seismic behavior of engineering structures and protect the main building components from damage. However, the complex BRB-to-reinforced concrete (RC) member connection is not conducive to the development of BRBs in RC frames, and the frame action effect may make the gusset plate more susceptive to premature fracture under severe earthquakes. In this paper, a novel BRB connection in which the gusset plate and RC components were entirely connected by the shear connectors was proposed for a more reliable BRB-to-RC joint in new RC building structures. The gusset-to-beam and gusset-to-column interfaces are significantly reduced due to the absence of the anchor plates, and thus the negative effect of the frame action can be remarkably eliminated. Based on the generalized uniform force method (GUFM), the seismic design approach of the proposed gusset plates was developed. Cyclic tests of two full-scale BRB-RCF subassemblages with different connection details were conducted to gain insights into the seismic performance of the proposed connections. The test results demonstrated that both the perfobond strip (PBL) and welded shear stub (WSS) gusset connections exhibited stable behavior even at the 3% interstory drift ratio (IDR). As expected in design, BRBs ruptured under low-cycle fatigue loading and the plastic hinges of the beams were successfully transferred to the outside of the gusset connection regions. No damage can be observed at the gusset plates during the tests, which indicates that the proposed connections and the design approach are effective. The Numerical analysis models were constructed and good agreement between the simulation results and the test results was observed.