EXPERIMENTAL STUDY ON MECHANICAL PERFORMANCE OF BUCKLING-RESTRAINED BRACE ON FRAMES WITH HIGH-STRENGTH CONCRETE-FILLED SQUARE STEEL TUBE COLUMNS

Using buckling-restrained braces (BRBs) in frames with high-strength concrete-filled square steel tube columns(HSCFSSTC) can solve issues such as brittle failure and low lateral stiffness. To investigate the mechanical performance of buckling-restrained brace frames(BRBFs), an experiment study was conducted. The investigation involved the design and analysis of a frame system composed of BRBs, HSCFSSTC and H-shaped steel beams. Sub-structures at a 1/3 scale with two types of connections, welded and pin connections, were subjected to pseudo-static tests. The influence of BRBF connection types on the plastic hinge formation mechanism, load-bearing capacity, energy dissipation capacity and stress magnitude of the connection gusset plates was examined. After the test, ABAQUS software was used for finite element analysis of the specimen, and the simulation results were in good agreement with the experimental results.Based on the results, both the welded and pin-connected specimens formed plastic hinges at column bases and the beam ends, which ensured the energy dissipation performance of BRBs. Pin connections were found to exhibit noticeable slippage during loading due to the presence of holes. However, the study found that the plastic hinge formation mechanism, load-bearing capacity, and lateral stiffness of the frames with the two connection types were similar. Furthermore, there was no significant difference in the load-bearing capacity, stress distribution, and magnitude between the two connection types. Nevertheless, welded connections demonstrated a greater potential for broader application as they allowed the BRB to resist horizontal seismic forces earlier than pin connections.