Seismic behavior of exterior connections between I-section beams and T-shaped close-section special-shaped all-steel columns

Special-shaped columns with close-section design are considered more advantageous than conventional circular or square columns, offering a desirable esthetic appearance and optimal utilization of indoor space, coupled with competent load-carrying capacity. This study systematically investigates the seismic behavior of a 1/2-scale welded connection between an I-section beam and a previously developed T-shaped close-section special-shaped all-steel column. Three distinct connection types at different strengthening levels of both beams and columns were constructed and tested under reversed cyclic load, with a compression ratio of 0.28 applied to the columns. Comparative analysis is conducted on the connections, focusing on damage patterns, failure modes, stiffness, load-carrying capacity, and deformation capacity. Furthermore, numerical study is undertaken to investigate the plastic region development and the energy dissipation mechanisms of the connections. The study results reveal that the connection involving the non-strengthened beam and the least strengthened column exhibits the greatest energy dissipation capacity among the connections. This is attributed to its favorable deformation capacity, complemented by appropriate load-carrying capacity. Moreover, it is observed that the beam-connected channels contribute to increased plastic regions within the connections, concurrently safeguarding the core tubes of the columns under earthquake scenarios.