Experimental study on the seismic behaviour of the connection between concrete-filled twin steel tubes column and steel beam

This study evaluates the feasibility of a new type of connection between the concrete-filled twin steel tubes (CFTST) column and steel beams. The formation and feature of the new connection were described firstly; it mainly consists of vertical stiffeners and embedded anchorage plates. The experiments were conducted on seven one-half scaled specimens including six CFTST column-beam joints and one square concrete-filled steel tube (CFST) column-beam joint. And, seismic behaviours including hysteresis curve, typical failure modes, load-carrying capacity, ductility, energy dissipation capacity, etc. were studied. Connections behaved as predicted that plastic hinges were achieved in steel beams. Connections with ribbed anchorage plates are of higher load-bearing and deformation capacity than connections with no ribs; the extension of the vertical stiffener can move the buckling zone away from the column, so the joint's initial stiffness was improved. The hysteretic characteristic of connections was stable; the energy dissipation capacity, strength and ductility were sufficient. In the whole loading, the stiffness degradation was obvious and bearing capacity degradation was slow. Test results show that connections with good aseismatic behaviour can easily achieve the anti-seismic design principle, namely strong column-weak beam and strong joint-weak member.