Scholarship & Research
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Item Pilot study of a high capacity ductile seismic holdown for cross laminated timber(Montana State University - Bozeman, College of Engineering, 2019) Nicholas, John Howison; Chairperson, Graduate Committee: Damon FickNew manufactured wood products referred to as mass timber have allowed for greater seismic load capacities than ever before for designing wood structures. The increased capacities could allow for taller wood structures; however, traditional wood connections do not meet the seismic performance needs for new manufactured wood products such as cross laminated timber (CLT). New connection methods must be investigated to allow for the growth of the CLT industry in mid- and high-rise structures. The objective of this research is to develop a wood connection to resist larger uplift forces experienced in CLT structures and provide energy dissipation in seismic events. The connection development was performed through fastener testing using self-drilling dowel fasteners for concealed connections with steel knife plates installed in a wood member. Finite element modeling and testing of reduced section steel plate to provide a ductile response to cyclic loading was performed to determine the feasibility of this connections style. The results of the investigation indicate that reduced section steel plates that limit the connection failure to a desired location in the steel plate could greatly increase the seismic performance of CLT seismic force resisting systems.Item Characterizing the mechanical and structural performance of hydraulic-lime CMU wall components and assemblies(Montana State University - Bozeman, College of Engineering, 2015) Haunt, Tucker Trostel; Chairperson, Graduate Committee: Michael BerryConcrete is the most commonly used building material in the world. As a result, the production of portland cement accounts for seven percent of the carbon dioxide produced by industry worldwide. A more environmentally-friendly alternative to portland cement could significantly reduce carbon dioxide emissions, and thus reduce the carbon footprint of the concrete industry. One possible alternative to portland cement is hydraulic lime, which creates less carbon dioxide during its production than portland cement. Further, hydraulic lime reabsorbs carbon dioxide as it cures, through carbonation. Despite these advantages, there are some logistical issues associated with using hydraulic lime in modern construction (e.g., increased cure times). Using hydraulic lime in concrete masonry units provides an opportunity to overcome some of these limitations and thus take advantage of the environmental benefits associated with its use. While the use of lime as the binder in masonry construction is not a new concept, modern building codes have evolved around components made with portland cement rather than hydraulic lime. The, research discussed herein investigates the mechanical and structural performance of hydraulic lime masonry components, and evaluates the efficacy of simple mechanics models used to predict their performance. First, the performance of individual masonry components (i.e., mortar, grout, and block) are evaluated, followed by an evaluation of simple masonry assemblies (e.g., prisms). Finally, a series of five wall assemblies were tested to determine the in-plane shear resistance of hydraulic-lime wall systems. It was found that while the strength of the hydraulic lime masonry components/assemblies were significantly less than those made with portland cement, the use of hydraulic lime in this application is feasible.