NONLINEAR NUMERICAL STUDY OF THE SEISMIC RESPONSE OF MODULAR MASS TIMBER BUILDINGS USING SUPERWOOD STRUCTURAL MEMBERS AND SELF-CENTERING PANELS

Abstract

Self-centering structural systems, with their high energy dissipation capacity and minimal residual drifts, have been the focus of contemporary studies in seismic design. These systems concentrate earthquake energy in replaceable fuse elements and enable rapid post-event recovery and immediate occupancy. They also offer innovative solutions for resilient construction when paired with sustainable construction strategies. A promising platform for implementing and scaling such technologies is modular mass timber construction, which has gained recognition for its inherent advantages such as rapid assembly, reduced construction time, and low environmental impact. However, conventional lateral force-resisting systems can sustain permanent damage under severe seismic loading, while low-ductility intermodular connections limit reusability, architectural flexibility, and buildingheight in modular buildings. This dissertation addresses these limitations by introducing a series of innovative modular self-centering systems. The seismic response of modular mass timber buildings that utilize superwood structural members and Self-Centering Superwood Boards (SC-SWB) is investigated. The SC-SWB system is developed as a lateral force-resisting mechanism that incorporates delignified-densified “superwood”, with exceptional mechanical properties, and stainless steel replaceable hysteretic dampers (RHD). Analytical expressions defining system behavior were derived and validated against 3D continuum and 2D wireframe finite element models. A three-story prototype structure designed for high seismicity was evaluated through nonlinear static (pushover) and dynamic (time history) analyses, with parametric studies examining its adaptability. Results demonstrate the system’s ability to maintain elastic behavior in primary structural members while exhibiting minimal to no residual drift. A design study of superwood structural members, including superwood-mass timber hybrid elements and modular hollow superwood structural sections, is then conducted. The enhanced performance and design limitations of each member are examined through parametric studies. The Self-Centering Modular Superwood Rocking Wall (SC-MRW) system, incorporating these hollow superwood elements and RHD coupling devices, is introduced next. Analytical formulations describing system behavior are derived and cross-validated against finite element simulations. Finally, the integration of SC-SWB modules into a complete modular mass timber building design, featuring decoupled gravity and lateral load-bearing systems that eliminate the intermodular connections, is explored. The global seismic performance of 3D macro-models is assessed under various design conditions, including torsional irregularities and module-level base isolation configurations. This research highlights the potential of the proposed systems to advance post-disaster resilience by overcoming key challenges in modular timber construction, particularly the limited reusability of structural components and the absence of resilient lateral force-resisting systems.