A case study on mixed angle screw hold-down connections for a 6-Storey CLT shear wall building

Mass timber structures are a growing topic in the New Zealand design environment. To design mass timber buildings to the moderate or high seismic demands of New Zealand, strong stiff, and ductile seismic systems are required. One such system recently developed and tested at the University of Canterbury is the mixed angle screw hold-down connection for Cross Laminated Timber (CLT) shear walls. Through the innovative use of large European self-tapping screws installed at mixed angles with respect to the grain, the strong and stiff performance of screws installed at 45° can be combined with the ductility and displacement capacity of screws installed at 90° to the grain, providing an overall strong, stiff, and ductile connection.