Code provisions for seismic design of multi-storey post-tensioned timber buildings
Recent developments and successful preliminary experimental validations of innovative types of ductile connections for multi-storey seismic-resisting laminated veneer lumber (LVL) timber buildings have opened major opportunities for extensive use of structural timber in seismic regions. These particular solutions, named jointed ductile connections or hybrid systems are based on post-tensioning techniques to assemble structural LVL members for both frame and shear wall systems which are designed to exhibit controlled rocking deformations during seismic loading. These systems have been proposed and uccessfully tested using concepts developed for high-performance seismic-resisting precast concrete buildings, currently being approved in major seismic codes and design guidelines worldwide. The extremely satisfactory results of quasi-static cyclic and pseudodynamic experimental tests on exterior beam-column joint subassemblies, column-to foundation connections and shear wall systems have provided valuable confirmation of the high seismic performance of these LVL systems, as well as the reliability of the adopted design criteria and methodology. In this paper, after a brief introduction to the concept of post-tensioned seismic-resisting LVL structures and an overview of experimental results, particular focus will be given to seismic design aspects, within a performance-based design approach, as a sound basis for the preparation of seismic design code provisions.