Damage-control design and hybrid tests of a full-scale two-story buckling-restrained braced steel moment frame with sliding gusset connections

Buckling-restrained braces (BRBs) are widely adopted as supplementary energy dissipation devices in steel moment frames (MFs) in Asia to improve the energy dissipation capacity of the whole system. Such systems are referred to as buckling-restrained braced moment frames (BRB-MFs). Nevertheless, adopting BRBs does not guarantee desirable seismic performance of the whole system, as frame action may cause premature fracture or buckling of BRB corner gusset connections, and such frame-to-gusset interaction may limit the ductility of such system. In our previous studies, a sliding corner gusset connection was proposed and proved to be able to substantially reduce the detrimental frame action at the connection level. In this paper, study was extended to (1) damage-control design of BRB-MFs with such connections in pursuit of enhanced system ductility, and (2) experimental evaluation on seismic behavior of BRB-MFs with such connections at the system level. The damage-control design method was first presented and a full-scale two-story BRB-MF designed by such procedure was experimentally studied under four levels of earthquake loading through hybrid tests, followed by a pseudo-static test to examine its failure mode. Test results showed that the sliding gusset connections effectively released the frame action at the system level. By adopting the damage-control design procedure, the test BRB-MF exhibited excellent seismic performance up to an inter-story drift ratio of +/- 3 %, and plastic hinges of the MFs developed in the controlled positions without fracture or buckling under four levels of earthquake loading. With the improved ductility of MFs, BRBs achieved their full potential as energy dissipation devices.