The Static and Dynamic Interface: Mass Timber Rocking Wall Resilience

In 2010 and 2011, Christchurch, New Zealand experienced multiple unprecedented earthquakes. One hundred and eightyfive lives were lost and, by 2015, 40% of buildings in central Christchurch had to be demolished due to structural damage. In that same year, LEVER Architecture won a competition hosted by the USDA and Softwood Lumber Board to develop Framework (Figure 1), a 12-story, 150 ft. tall mass timber building in Portland, Oregon, a region of high seismicity in the United States. The project team, many with direct experience of the New Zealand earthquakes, focused on designing a sustainable, resilient, damage-resistant building. To serve as a demonstration of mass timber’s structural and aesthetic capabilities for tall buildings in seismic zones, the entire superstructure of the project is composed of mass timber, including both gravity and lateral force-resisting systems (Figure 2). The most innovative feature of the building’s lateral system is its post-tensioned re-centering rocking wall. This system was chosen as an opportunity to advance the architectural and structural engineering professions’ understanding of tall, recentering mass timber wall buildings, their requisite performance-based engineering methods, review criteria by the Authority Having Jurisdiction (AHJ), and best practices for detailing the interface between the rocking wall and static building elements, i.e., deformation compatibility. The design team focused on maximizing exposure of wood structural elements, a challenge that required successful fire-testing of previously unproven assemblies to ensure exposed timber structural elements and their concealed connectors met the fire-resistance requirements while also accommodating The Static and Dynamic Interface: Mass Timber Rocking Wall Resilience