Development and Testing of Innovative Earthquake-Resistant Systems for Hybrid Wood-Steel Structures

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The objective this research program is to develop novel and innovative high-performance earthquake-resistant systems for wood structures. This will be accomplished through the design of new hybrid wood-steel structural forms, which take advantage of the high strength-to-weight ratio, sustainability, and aesthetic value of wood, and the excellent earthquake performance of advanced steel passive damping systems. The type of wood building that most people are most familiar with is a residential house. This is a light-frame structure made of wood walls which consist of plywood sheathing nailed to lumber studs. There has been a recent push in Europe and North America to start to build different types of structures out of wood more often. For example, the “Wood First” initiative in British Columbia mandates that all new government structures must be constructed out of wood if possible. To fully meet this need, new research is required to determine how to best build larger and taller structures. Instead of using light-frame construction methods, these larger structures are typically built using heavy timber beams and columns and/or solid wood walls. One of the most significant challenges in the design of these larger and taller buildings in timber is to determine how to properly design them to resist earthquakes. Since wood is a brittle material, wood structures often rely on the bending and deformation of steel bolts or nails to accommodate the severe shaking caused by earthquakes. This design method tends to result in significant damage to wood building elements. This research program will investigate ways to prevent damage in the wood members by using specially-designed steel elements to limit the loads in the wood members and to dissipate energy from the structure during an earthquake. These steel elements accommodate and resist the earthquake loads through the action of special “self-centering” mechanisms, which provide the added benefit that they return a structure to a fully upright position during and after an earthquake.These types of high-performance earthquake resistant elements have been previously applied widely in steel and concrete structures. This research program will develop ways to integrate existing high-performance earthquake dampers and structural forms into a wood context to increase the performance and competitiveness of wood buildings. New cross-brace connections for heavy timber frames will be developed and tested that are designed to prevent wood members from being damaged while permitting the introduction of self-centering cross-braces. Full-scale self-centering beam-to-column connections that utilize long steel pretensioned tendons will be adapted to wood frame systems and tested in the laboratory. In addition, solid timber walls which are allowed to rock at their foundation and at every level above will be designed, modelled and tested.It is anticipated that this research program will increase the competitiveness of wood for use in the construction of larger and taller residential, commercial and industrial structures, especially in seismically active zones in British Columbia, Quebec and Eastern Ontario. Hopefully, this will, in turn, benefit the Canadian forestry industry and, therefore, the Canadian economy and society at large.