Structural Performance of Post-Tensioned CLT Shear Walls with Energy Dissipators

The prestressed-laminated timber (Pres-Lam) system is an innovative low-damage wood-hybrid system that utilizes post-tensioned (PT) mass timber components, e.g., laminated veneer lumber (LVL), glued laminated timber (glulam), and cross laminated timber (CLT), along with various types of energy dissipators, e.g., axial energy dissipators (also called fuses) and U-shaped flexural plates (UFPs). Previous tests carried out on this system focused on scaled (one-third or two-thirds) LVL specimens, whereas limited studies have been conducted on the Pres-Lam system with CLT which has mechanical properties and composition different from LVL. Through comprehensive tests, the lateral-load response of PT-only and Pres-Lam CLT shear walls was investigated in this study. A total of 14 different full-scale PT-only and Pres-Lam CLT walls in four configurations were tested under monotonic and reversed cyclic loading. A user-friendly fuse was designed and adopted in the Pres-Lam CLT wall specimens. PT-only and Pres-Lam CLT shear walls had bilinear elastic and elastic-plastic behavior, respectively, with a stretching point corresponding to the state at which the PT force started to increase. With energy dissipators, Pres-Lam CLT shear walls had higher resistance, maximum lateral drift and energy dissipation compared to PT-only walls. The influence of the initial PT force, the fuse spacing, and the number of UFPs on the stiffness, resistance, maximum lateral drift and energy dissipation of the wall specimens was discussed. The test results also show that the behavior of the Pres-Lam CLT shear walls can be decoupled and a superposition rule can be applied to obtain the stiffness and resistance of such systems. Yielding and buckling of the fuses occurred at the early stage of loading as designed, and localized crushing of wood at the end of panels happened when the lateral drift was at or beyond 2.5%. The test results gave a valuable insight into the structural behavior of the PT-only and Pres-Lam CLT shear walls under in-plane lateral loads. (C) 2020 American Society of Civil Engineers.