QUASI-STATIC CYCLIC TESTS ON THE HYSTERETIC BEHAVIOR OF BUCKLING-RESTRAINED BRACES WITH A T-SECTION CORE

Abstract

An all-steel assembled buckling-restrained brace is proposed, in which both the core and the restraining members are made of section-steel. The brace has the advantages of assembly, replaceable core, easy fabrication, low cost and can be used for strengthening existing members. The steel core is composed of two angle steels and stiffening plates to form a T-shaped section. The restraining members are formed by bolting plates and angle steels through mat strips. Quasi-static cyclic tests for six specimens were carried out to investigate the hysteretic performance, seismic performance and failure modes. The effects of adding filler plates in the core, the gap between the core and the restraining members, the spacing between the two angle steels of the core, and the stopper configuration on the hysteretic performance were analyzed. The results show that the actual performance of the brace was basically consistent with the design performance. The brace specimens exhibited stable hysteretic performance. Adding filler plates in the middle of the core shows little influence on the hysteresis performance. An excessive gap between the core and the restraining member and excessive spacing between the two steel angles of the core reduced the hysteresis performance. The hysteretic performance of the braces with middle stoppers were better than the brace with end stoppers. The analysis of the seismic performance of the specimens shows that the braces have satisfactory ductility and cumulative plastic deformation capacity, which can be used as dampers in structures. By analyzing the failure modes, the stress concentration of the welding at the end of the stiffening plates will make the failure position move from the yielding segment to the stop of the weld. The middle stopper of the core can reduce the adverse effects of friction.