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Due to the efficiency, sustainability, and advances in firefighting technologies, the allowable height for wood buildings was increased from 4 to 6 storeys in 2015 and will be further increased to 12 storeys in the 2020 edition of the National Building Code of Canada, as a result of the advent and application of mass timber products. To match the development in the industry and the increasing need in the market for highly skilled timber engineers, structural timber design curricula at the university level must evolve to train the next generation of practitioners. At most Canadian universities, structural timber design courses are mainly provided in civil engineering departments. In this study, 31 accredited civil engineering programs in Canada were reviewed for structural wood design content at undergraduate and graduate levels based on two surveys conducted in 2018 and 2020. In the 2018 survey, the percentage of structural timber design content was estimated and compared with other engineering materials (e.g., steel, concrete, and masonry), and a similar survey was repeated in 2020 to determine if any significant changes had occurred. In early 2021, two complementary questionnaires were sent to the instructors of timber-related courses across the country to collect quantitative information, including enrollment statistics, percentage dedicated to timber design in combined material courses, and potential topics deemed critical to support the design of modern timber structures. Based on the responses provided, and also on the availability of resources and the research ongoing, the content for five advanced-level courses is proposed to address the needs of the timber design community. The findings presented in this paper will assist the timber industry, government agencies, and educational institutions in effecting potential changes to university curricula to educate the next generation of timber design professionals who will possess the necessary skills and knowledge to meet the challenges in designing modern mass timber structures.

Prefabricated wood construction relies heavily on efficient material handling, yet rigging system design for floor panels remains understudied. This study introduces a novel rigging device that attaches to prefabricated wood I-joist floor panels using self-tapping screws, avoiding potential damage caused by predrilled holes in the sheathing panels and framing members. To establish allowable lifting capacities and optimal installation practices, comprehensive withdrawal tests were conducted on 114-floor panel specimens. Factors influencing withdrawal capacity, such as anchor plate placements, flange materials and width, screw type and quantity, and sheathing panel thickness, were systematically evaluated. Results indicate that withdrawal capacity does not scale linearly with screw quantity and that anchor plates with eight screws centered on the flange enhance performance by up to 20% compared to four-screw configurations. Unexpectedly, thinner sheathing panels yielded higher capacities, potentially due to increased screw penetration depth in the joist flange. In addition, anchor plate orientation, flange width, and flange materials also impact capacity. These findings provide essential data for designing reliable and efficient rigging systems in prefabricated wood construction. [ABSTRACT FROM AUTHOR]

This paper introduces a new low-damage hybrid steel–timber rocking braced frame with self-centring capability and proposes a design methodology in the framework of Canadian design standards. This system consists of a gravity load-resisting timber frame and a steel concentrically braced frame acting as the lateral load-resisting system that is connected using U-shaped steel fuses. The self-centring capability is achieved by post-tensioning strands and rocking bases within the lateral load-resisting system. The system, along with its components, is first introduced. The proposed design method and system performance objectives are then presented. The seismic performance of the system and the proposed design procedure are validated through numerical analyses considering the interaction between the lateral and gravity load-resisting systems. The results of dynamic analyses confirm the enhanced seismic performance of the proposed hybrid system with almost no residual deformations after the earthquake. Moreover, the proposed design guidelines can accurately predict the system's seismic response and demands imposed on the members. [ABSTRACT FROM AUTHOR]

Trembling aspen (Populus tremuloides) is one of the major species within Populus, a predominant genus of hardwoods in North America. However, its utilization has been limited to pulp and paper or wood-based composite boards. This study aimed at evaluating the major physical and mechanical properties of trembling aspen lumber, with an ultimate objective of using this species to produce engineered wood products (EWPs). The testing materials consisted of 2 × 4 (38 mm × 89 mm) trembling aspen lumber pieces in lengths of 8, 10, and 12 feet (2.44, 3.05, and 3.66 m) with two visual grades, select structural (SS) and No. 2. Machine Stress-Rated (MSR), and longitudinal stress wave (LSW), edgewise third-point bending (EWB), and axial tension tests were conducted on the lumber. It was found that, (1) by increasing the maximum knot size by a half-inch from one-quarter inch, the minimum modulus of elasticity (MOE) measured using the MSR, the mean, and the fifth-percentile ultimate tensile strength (UTS) decreased by about 8.8%, 20.1%, and 29.8%, respectively. (2) Approximately 44% of the trembling aspen lumber met the 1450f-1.3E grade for MSR lumber, and 62% qualified for the 1200f-1.2E grade. (3) There was a great potential for manufacturing cross-laminated timber (CLT) of grade E3, with a rejection rate of about 29%. (4) The mean UTS and MOE values of the SS-grade trembling aspen lumber were 22.88 MPa and 9519 MPa, respectively, being 25.5% and 11.3% lower than that of Spruce–Pine–Fir (S-P-F) lumber. The fifth-percentile UTS and MOE values were 11.57 MPa and 7404 MPa, respectively, marking a decrease of 13.3% and 1.5% compared to the S-P-F lumber. (5) The oven-dried specific gravity (SG) of the trembling aspen wood was 0.40, which was about 3.5% larger than the value provided in the Wood Handbook. [ABSTRACT FROM AUTHOR]

Panelized fabrication of light-frame wood buildings has higher productivity than the traditional stick-built method. However, the roof production process is inefficient due to the structural system and construction method. This study proposes a novel roof system to improve the productivity of the panelized construction process for light-frame wood residential building fabrication. This unique system uses a holistic approach to design several roof components considering structural requirements, manufacturing efficiency, and on-site installation factors. This paper presents a case study of the gable roof of a two-story building to demonstrate the implementation of this novel system. The two main components of the novel roof system are the ceiling frame and roof panels. Ceiling frame analysis showed that three different fabrication options are possible in the current off-site setting. Twenty-four nail-connection specimens were tested under shear and uplift loading to determine the load–slip response of nail connections used in structural composite wood such as oriented strand board (OSB) and laminated strand lumber (LSL). The roof panel design requirement was determined based on the nail connection test and finite-element analysis. The results showed that ceiling frames for a gable-type roof can be produced economically using a floor panel production line, and roof panel fabrication is possible using the current wall panel production line. [ABSTRACT FROM AUTHOR]

The main objective of this study was to develop an analytical model for predicting the diaphragm deflection and the induced shear force at the panel joints when the applied load is perpendicular to the panel length. An equivalent finite-element model was developed to capture the elastic behavior of the diaphragm made from the panels and the connections in between. The analytical model's predictions were compared with predictions from finite-element models. The results of an experimental test were used to partially validate the analytical and numerical models in the absence of full-scale diaphragm test data. A sensitivity analysis was carried out with the aim of finding the most influential parameters in the behavior of the cross-laminated timber (CLT) diaphragm. The connection's stiffness and diaphragm size were varied. The difference in diaphragm deflection was investigated, and it was found that under realistic material properties and geometry, the diaphragm deflection was not strongly related to the connection's stiffness. However, the floor's geometry was the key influencing parameter. A parametric study was performed, and the contribution of each deflection component was quantified for each specific case. It was observed that the floor's flexibility was dominated mainly by the shear deflection of the cross-laminated timber panels as well as the slip in the panel joints as the length of the diaphragm increased. This study proposes a method that designers may use to estimate the in-plane displacement of the cross-laminated timber diaphragm when it is loaded perpendicular to the panel's length. [ABSTRACT FROM AUTHOR]