Feasibility study on a self-centering beam-to-column connection by using the superelastic behavior of SMAs

High ductility in traditional beam-to-column connections is often coupled with beam local buckling. These plastic local buckling deformations are difficult and very costly to repair in any post-disaster reconstruction. This paper investigates a new connection consisting of an extended end-plate, long shank SMA bolts, continuity plates, beam flange ribs and web stiffeners. Advanced 3D models of traditional end-plate bolted connection and the SMA connection are created, and the behavior of the two types of connections is compared. The results show obvious cyclic elongations of the bolts in the SMA connection compared to the beam local buckling in the traditional connection. Rather than the plastic hinge forming away from the column face in the traditional connection, a superelastic hinge forms just at the beam-to-column interface in the SMA connection with the moment-carrying capacity of bolt cluster controlled below the elastic flexural capacity of the connecting beam. The connection deformations are recoverable upon unloading. Moreover, the SMA connection ductility is significantly influenced by the length of the SMA bolts. For SMA bolts which are 1.2 times longer than the standard bolt, the inelastic interstory drift angle reaches 0.035 rad, which indicates that the proposed connection can be designed with sufficient ductility.