Mass timber (MT) building systems are gaining momentum around the world, especially in Canada where Federal and Provincial governments encourage the greater use of wood in construction projects through various promotion programs such as GCWood Program. In the meanwhile, seismic design provisions in the 2020 National Building Code of Canada have been revised, resulting in significantly higher seismic loads for structures in many locations. Consequently, there is a need to develop new lateral load resisting systems that allow mass timber structures to better compete against their counterparts in steel, concrete and masonry. Building on the success of midply shear walls for wood-frame construction, a multi-year research project was initiated at FPInnovaitons to develop MT version of midply shear wall systems that have greater structural capacities, fire, and acoustical performance.
In the first year of this project, literature reviews were conducted to identify the code requirements on MT components and to survey the available LLRSs used in the MTstructures. Conceptual MT midply wall systems meeting structural, fire, and acoustical performance requirements were proposed. An advisory group meeting was held to evaluate the practicability of the proposed MT midply systems. In the next fiscal year, the proposed MT Midply will be optimised further according to the comments and suggestions from the advisory group. Analytical evaluation of the proposed MT Midply wall systems along with necessary tests will be conducted. Based on the evaluation, a go / no-go decision will be made as to whether the study should be continued for the proposed MT Midply.
National Building Code of Canada (NBC) 2020 is the latest edition of the national model code that will be published towards the end of 2021. Based on the best available information from the Standing Committee on Earthquake Design (SCED) at the time of writing this report, the seismic design demand in the NBC 2020 has increased for all site classes for many locations across the country. Also, there are other changes in NBC 2020 that might impact the seismic analysis and design of timber buildings. The main objective of this report is to compare the NBC 2020 to the 2015 edition, with emphasis on the level of the seismic design loads (demands), and potential impacts on the analysis and design of timber buildings.
Abstract
Across B.C. and Canada, communities are under pressure to create better-performing buildings that meet stringent code requirements while reducing construction waste. Meanwhile, consumers are demanding high-quality structures that are delivered quickly and at a reasonable price. Modern methods of construction that include prefabrication can help construction professionals create buildings that meet all these criteria.
Furthermore, prefabrication provides steady employment and is good for the economy. The market opportunities are present across Canada and in the U.S., but prefabrication is not being used to its potential due to several barriers:
Negative perception of quality
Fear of innovation
Lack of information and understanding
Unclear economic benefits
Limited industry capacity
Planning and regulatory complications
Recommendations
A concerted effort to address these barriers includes:
Improving products through research and development
Researching, documenting, and promoting best practices
Developing guidance documents so prefabrication is easier to incorporate
Providing national-level leadership and resources to promote innovation
Successfully implementing these recommendations will require a broad and deep national perspective, an understanding of all stages and aspects of wood construction, and the vision and skills to bring together diverse experts and stakeholders.
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