"Seismic response of post-tensioned LVL walls coupled with plywood sheets"

Laminated veneer lumber (LVL) structural members have recently been proposed for multi-storey timber buildings based on ongoing research at University of Canterbury, New Zealand. The members are designed with unbonded post-tensioning for recentering and ductile connections for energy dissipation. This paper describes the experimental and numerical investigation of post-tensioned LVL walls coupled with plywood sheets under both quasi-static cyclic and pseudo-dynamic seismic testing protocols. It is observed that energy is dissipated mostly through yielding of the nails, and the LVL walls return close to their initial position while remaining virtually undamaged. Different arrangements of nails have been tested to compare their energy dissipation characteristics. Numerical models with appropriate elements to represent the contact interface at the base as well as simulating post-tensioning and hysteresis have been developed to predict the behaviour of the systems and they match the experimental results with good accuracy. The results indicate good seismic performance, characterized by negligible damage of the structural members and very small residual deformations. The only component significantly damaged is the nailed connection between the plywood sheet and the LVL walls. The plywood can be easily removed and replaced with new sheets after an earthquake, which is reasonably cheap and easy to install, allowing for major reduction in downtime. Other advantages include low mass, flexibility of design and rapidity of construction. Post-tensioning of structural members involves low-cost and can be easily arranged on site. With all these benefits together, the concept has potential for consideration as an alternative solution for multi-storey timber buildings.