Seismic response of extended end plate joints to concrete-filled steel tubular columns

This paper investigates the seismic behaviour of extended end plate connections to circular or square concrete-filled steel tubular (CFST) columns using blind bolts. Both the end plate type and the column section type are considered. Results of an experimental study involving four bolted moment-resisting connections subjected to cyclic loading are presented. The failure modes, hysteretic performance, strength and stiffness degradation, rigidity classification, and energy dissipation of the blind bolted extended end plate connections to CFST columns were estimated in detail to investigate the seismic behaviour. The anchorage action of reinforcing rebar welded to the bolt with concrete-filled steel tubes was also explored. The experimental results indicated the blind bolted extended end plate connections with circular or square CFST columns exhibited large hysteretic loops, good ductility, and excellent energy dissipation capacity. Failure modes for test specimens under cyclic loading were similar to those under monotonic loading, and their rotation capacities satisfied the ductility design requirements for earthquake-resistance in most seismic regions. These experimental studies enable improvement in the practical design of blind bolted moment connections.