Seismic resilience timber connection—adoption of shape memory alloy tubes as dowels

This study investigates a novel timber dowel-type connection system using superelastic shape memory alloy (SMA) bar and tubes as dowels, in order to provide self-centering effect. Double-shear connections with SMA and mild steel dowels were tested under dynamic loadings at different displacement levels. The results showed that SMA dowel-type connections have good self-centering behaviours and can mitigate the residual deformation effectively compared with steel dowel-type connections after excessive deformation; although the steel dowel-type connections present higher strength. These tests reveal that the connection with tube dowels show higher equivalent viscous damping ratio than those use solid bar as tube would allow larger deformation to dissipate energy. To demonstrate application of the benefit of this system, an analytical model of a 3-storey timber framed structure was built for parametric study. The results showed that the structures with conventional dowel-type type connections exhibit large unrecoverable deformation after timber framed structures experience an earthquake. In comparison, those with the connections developed in this project show limited unrecoverable deformation due to the self-centering capacity of the connections.