Cross-Laminated Timber (CLT), has increased the possibilities of building with wood. CLT consists of multi-layer panels, manufactured with lumber boards that are glued together, alternating the direction of their fibers for each layer. The successful introduction of CLT into the Canadian market indicates that there is potential for further market penetration in North America, and more specifically the United States. To increase the understanding of the market potential for CLT in the U.S., this dissertation aimed at identifying the critical factors influencing the willingness of U.S. construction professionals to adopt innovative wood-based construction materials, such as CLT. The overall objective was achieved by: (a) investigating the level of awareness, perceptions, and willingness to adopt CLT among structural engineers and construction firms; (b) developing a conceptual model including the most critical factors that influence the adoption of innovate wood-based construction materials among structural engineers and construction firms; and (c) identifying distinct market segments for CLT adoption in the U.S. The outcomes from this research help fill the gap in the knowledge about the market adoption process for innovative wood-based materials in the construction industry. This study also contributes to advance the development of the CLT industry in the U.S. by increasing the demand of wood-based construction materials and supporting the creation of employment in a sector of critical importance to the U.S. economy. Findings from this thesis provide useful information that will help these actors accelerate the adoption of CLT through well-designed educational programs, demonstration projects, marketing strategies, and policy incentives.
One of the recent additions to the panoply of engineered wood products is cross-laminated timber (CLT). CLT is a prefabricated, large-scale, solid wood panel that consists of multiple layers of lumbers stacked together, with each layer arranged perpendicular to the next layer, glued with structural grade adhesives, and pressed. The use of massive CLT panels in wood construction provides several advantages over the traditional wood frame systems, making it particularly attractive for tall wood building construction. These main advantages are satisfactory distribution of defects, adequate seismic performance, ability to carry large loads, improved strength and stiffness, adequate acceptable fire performance, acceptable acoustic performance, and improved pre-fabrication.It is expected that as the CLT market will continue to mature, more diversified grades and special CLT products will be introduced into the markets. One special CLT product developed in at Oregon State University has been designated as hybrid CLT. Hybrid CLT refers to CLT panels manufactured with layers of high- and low-grade and low-density species, which aims at improving the economic efficiency and sustainability of the CLT industry with focus on the North America market.One of the potential issues with hybrid CLT panel application is related to the unknown performance of the connection systems which are highly dependent on the density of the wood in which the fasteners embed. Most of the existing models that have been developed for estimation of the fasteners capacities in withdrawal and lateral loading scenarios are developed based on the assumption of uniform density profile across the layers to which fasteners penetrate. In a hybrid CLT panel, there is a possibility of a variation in density profile along the panel thickness so that the fasteners can be driven into wood of different densities and driven in directions parallel and perpendicular to grain. Because of the potential variation in density profile in the hybrid CLT, the connection system performance cannot be predicted using design models used for uniform density profile applications similar to the models in National Design Specification (NDS) . Therefore, there is a need for evaluation of connections performance in hybrid layup.The main objective of this work is to characterize the performance of connection systems for hybrid CLT. This is achieved through testing and modeling of single fastener connections and then testing and modeling of the typical connection systems. So, the specific objectives are: (1) evaluate the single fasteners performance to account for density variation and compare the results to a proposed modified model, (2) perform an experimental program to test different connection systems with different hybrid CLT panel layups, (3) develop a numerical algorithm based on the use of meta-heuristics tools to fit the optimal parameters for constitutive models to match the experimental data for the connection systems, (4) obtain the optimal parameters for constitutive models of the connection systems tested.
Wood-frame is the most common construction type for residential buildings in North America. However, there is a limit to the height of the building using a traditional wood-frame structure. Cross-laminated timber (CLT) provides possible solutions to mid-...
CLT is becoming global. New countries and regions increasingly realize the potential of what can be done with CLT. As a result, new markets are forming and new companies are entering the industry. Every new region or country that opens its doors to CLT has its own challenges and opportunities. However, there is the unique opportunity to learn from the existing Original Market in Europe and the companies that have been successful there for many years. Especially the German-speaking alpine region was, and still is, the cradle of CLT innovation. Therefore, this research,using qualitative methods, analyzed market characteristics and business models of this region. Lessons learned over the years were identified such as the importance of high-level timber education, the role of designing for building services, hype versus reality with respect to tall wood buildings and how careful design processes are key to competitiveness of CLT buildings. Threats and challenges in the North American CLT market were also identified there. The combined findings give an enhanced understanding of how the implementation of CLT in North America, as an example of a new global market, can be fostered.