Experimental seismic behaviour of bottom-through-diaphragm and top-ring connection to SST columns

A new type of connection called bottom-through-diaphragm and top-ring connection to square steel tubular (SST) columns is presented in this paper. Five specimens were designed to investigate the seismic behaviour of this new type connection under cyclic test. Three different configurations were considered in this test, the panel zone enhanced with T-stub, different thicknesses of square steel tubular columns and top-ring plate modified with vertical plate. The failure modes, hysteretic curves, rotation capacity, stiffness degradation, skeleton curves, ductility, and energy dissipation of these connections were analyzed. The effects of these configurations on the connection seismic performance were evaluated. The experimental results indicated that the new bottom-through-diaphragm and top-ring connection to square steel tubular columns exhibited stable and plump hysteretic curves, favourable ductility, and excellent energy dissipation. This proposed connection satisfies the seismic provisions to be utilized in moment-resisting frames.