Cyclic tests for steel frame with unbonded steel plate brace encased in panel

Abstract Quasi-static tests for two panel buckling-restrained braced frames (panel BRBFs), each of which consists of one two-story steel frame and two diagonal or chevron-shaped panel buckling-restrained braces (panel BRBs), were done to examine the impacts of constructional details on hysteretic response of the panel BRBFs (PBRBFs). Each panel BRB consists of one unbonded steel brace and either one assembled steel panel or one steel-concrete composite panel. Obvious yielding of panel BRBs and framing members developed from inter-story drifts of approximately 1/375 and 1/75 respectively. Local buckling of unreinforced segments of beams occurred when story drifts nearly reached 1/50. Local buckling of columns and tension fracture of steel components occurred at story drifts far larger than 1/50. The PBRBFs didn’t fail within story drifts of 1/30 in the first load stages and still exhibited stable behavior before eventual failure, which was attributed to tension fracture of either encased braces or other components, in the second load stages. The skeleton curves of each specimen are close to a trilinear model and those of both panel BRBs and frame are close to a bilinear model. All panel BRBs exhibited good ductility and qualified cumulative inelastic deformation capacity. The tests revealed that the capacity design generally confines most inelastic action in panel BRBs within story drifts of 1/50. The constructional details, including configurations of panel BRBs, width-to-thickness ratios of elements that meet moderately ductile requirement for H-shaped framing members, strengthening measures and connections, were generally acceptable to ensure good performance of the panel BRBFs.