Hybrid System of Unbonded Post-Tensioned CLT Panels and Light-Frame Wood Shear Walls

Abstract

Cross-laminated timber (CLT) is a relatively new type of massive timber system that has shown to possess excellent mechanical properties and structural behavior in building construction. When post-tensioned with high-strength tendons, CLT panels perform well under cyclic loadings because of two key characteristics: their rocking behavior and self-centering capacity. Although post-tensioned rocking CLT panels can carry heavy gravity loads, resist lateral loads, and self-center after a seismic event, they are heavy and form a pinched hysteresis, thereby limiting energy dissipation. Conversely, conventional light-frame wood shear walls (LiFS) provide a large amount of energy dissipation from fastener slip and, as their name implies, are lightweight, thereby reducing inertial forces during earthquakes. The combination of these different lateral behaviors can help improve the performance of buildings during strong ground shaking, but issues of deformation compatibility exist. This study presents the results of a numerical study to examine the behavior of post-tensioned CLT walls under cyclic loadings. A well-known 10-parameter model was applied to simulate the performance of a CLT-LiFS hybrid system. The post-tensioned CLT wall model was designed on the basis of a modified monolithic beam analogy that was originally developed for precast concrete-jointed ductile connections. Several tests on post-tensioned CLT panels and hybrid walls were implemented at the Large Scale Structural Lab at the University of Alabama to validate the numerical model, and the results showed very good agreement with the numerical model. Finally, incremental dynamic analysis on system level models was compared with conventional light-frame wood system models.