Evaluation of CLT Bracing Walls Using the P21 Cyclic Testing Protocol

This study investigates the feasibility of using CLT shear walls to replace some or all light timber frame bracing walls in residential buildings that are within the scope of NZS 3604. The proposed wall configuration uses a continuous steel base angle with a series of uniformly spaced self-tapping screws to provide shear and moment resistance at the base of the wall. Three full-scale, 3-ply CLT wall specimens were cyclically tested using the P21 loading protocol to evaluate their hysteretic behaviour. Each wall exhibited a ductile failure mode through screw yielding until eventual fracture of some base screws. The hysteretic behaviour was more severely pinched than plasterboard or plywood-sheathed light timber frame shear walls. The performance of these walls is considered compatible with typical bracing walls in the scope of NZS 3604 because they yielded at a similar drift ratio (between 0.1-0.21%) and their ultimate strength was reached at a drift ratio between 0.9-1.9% drift. A strength method from the literature was able to conservatively predict the strengths of the three wall specimens.