Experimental performance and structural analysis of plywood-coupled LVL walls

Prestressed-laminated timber (Pres-Lam) design has recently been adopted for multistory timber buildings based on ongoing research at the University of Canterbury, New Zealand. This system combines large timber members with unbonded posttensioning for recentering and ductile connections for energy dissipation. This paper describes the experimental, analytical, and numerical investigation of posttensioned laminated veneer lumber (LVL) walls coupled with plywood sheets subjected to both quasi-static cyclic and pseudodynamic seismic testing protocols. Different arrangements of nails, used to connect the plywood coupling panels with the posttensioned timber walls, have been tested to compare their energy dissipation characteristics. Simplified numerical macromodels with rotational spring elements have been developed to accurately represent the recentering contribution from the posttensioning and the pinched hysteric contribution of the nailed connections. The testing results provided good seismic performance, characterized by negligible damage of the structural members and very small residual deformations following drift levels of 2–2.5%. The only components significantly damaged, as designed, were the nailed connections between the plywood sheets and the LVL walls. These plywood sheets can be easily and cheaply removed and replaced with new sheets after an earthquake, creating a major reduction in postearthquake downtime. Combining these benefits together, the concept has potential for consideration as a cost-effective, high-performance solution for multistory timber buildings.