Ce rapport décrit les résultats d’études en cours ou antérieures réalisées par Forintek sur les méthodes utilisées pour l’aboutage du bois et la qualité des produits. Il donne une description détaillée des différents paramètres susceptibles d’affecter le procédé d’aboutage et la qualité du produit fini. Il contient également une masse de renseignements publiés dans le cadre d’ateliers, de conférences ou de revues techniques. Cette information a été regroupée et intégrée dans un format simplifié de façon à être utilisable dans la fabrication des bois aboutés. L’un des chapitres porte sur le processus de qualification et de contrôle de la qualité des bois de charpente aboutés et décrit les normes canadiennes de produits spéciaux applicables. On trouvera à la fin de chaque section un paragraphe traitant d’idées de recherche novatrices, de questions importantes pour l’industrie canadienne du bois abouté et de lacunes dans les connaissances.
Neither the National Building Code of Canada (NBCC) [1], nor any provincial code, such as the British Columbia Building Code (BCBC) [2], currently provide “acceptable solutions” to permit the construction of tall wood buildings, that is buildings of 7 stories and above. British Columbia, however, was the first province in Canada to allow mid-rise (5/6 storey) wood construction and other provinces have since followed. As more mid-rise wood buildings are erected, their benefits are becoming apparent to the industry, and therefore they are gaining popularity and becoming more desirable.
Forest product research has now begun to shift towards more substantial buildings, particularly in terms of height. High-rise buildings, typically taller than 6 storeys, are currently required to achieve 2 h fire resistance ratings (FRR) for floors and other structural elements, and need to be of non-combustible construction, as per the “acceptable solutions” of Division B of the NBCC [1]. In order for a tall wood building to be approved, it must follow an “alternative solution” approach, which requires demonstrating that the design provides an equivalent or greater level of safety as compared to an accepted solution using non-combustible construction. One method to achieve this level of safety is by ‘encapsulating’ the assembly to provide additional protection before wood elements become involved in the fire, as intended by the Code objectives and functional statements (i.e., prolong the time before the wood elements potentially start to char and their structural capacity is affected). It is also necessary to demonstrate that the assembly, in particular the interior finishes, conform to any necessary flame spread requirements.
The Technical Guide for the Design and Construction of Tall Wood Buildings in Canada [3] recommends designing a tall wood building so that it is code-conforming in all respects, except that it employs mass timber construction. The guide presents various encapsulation methods, from full encapsulation of all wood elements to partial protection of select elements. National Research Council Canada (NRC), FPInnovations, and the Canadian Wood Council (CWC) began specifically investigating encapsulation techniques during their Mid-Rise Wood Buildings Consortium research project, and demonstrated that direct applied gypsum board, cement board and gypsum-concrete can delay the effects of fire on a wood substrate [4].
There is extensive data on the use of gypsum board as a means of encapsulation for wood-frame assemblies and cold-formed steel assemblies. However, tall wood buildings are more likely to employ mass timber elements due to higher load conditions, requirements for longer fire resistance ratings, as well as other factors. There is little knowledge currently available related to using gypsum board directly applied to mass timber, or in other configurations, for fire protection. Testing performed to date has been limited to direct applied Type X gypsum board using standard screw spacing, and showed promising results [5, 6, 7]. This represents an opportunity for other configurations that might provide enhanced protection of wood elements to be investigated.
Being able to provide equivalent fire performance of assemblies between non-combustible and combustible construction will thus improve the competiveness of tall timber buildings by providing additional options for designers.
Lack of research and design information for the seismic performance of balloon-type CLT shear walls prevents CLT from being used as an acceptable solution to resist seismic loads in balloon-type mass-timber buildings. To quantify the performance of balloon-type CLT structures subjected to lateral loads and create the research background for future code implementation of balloon-type CLT systems in CSA O86 and NBCC, FPInnovations initiated a project to determine the behaviour of balloon-type CLT construction. A series of tests on balloon-type CLT walls and connections used in these walls were conducted. Analytical models were developed based on engineering principles and basic mechanics to predict the deflection and resistance of the balloon-type CLT shear walls. This report covers the work related to development of the analytical models and the tests on balloon-type CLT walls that the models were verified against.
The objective of this research is to address a knowledge gap related to fire performance of midply shear walls. Testing has already been done to establish the structural performance of these assemblies. To ensure their safe implementation and their broad acceptance, this project will establish fire resistance ratings for midply shear walls. Fire tests will provide information for the development of design considerations for midply shear walls and confirm that they can achieve at least 1-hour fire-resistance ratings that are required for use in mid-rise buildings.
This research will support greater adoption of mid-rise residential and non-residential wood-frame construction and improve competition with similar buildings of noncombustible construction. This work will also support the development of the APA system report for midply walls, which will be a design guideline for using midply walls in North America.
Cette étude compare les performances des différentes machines de classement MSR utilisées actuellement dans l’industrie canadienne du bois de sciage. Cinq machines ont été retenues : La HCLT-7200 de Metriguard, la Dart de Eldeco, la TMG du CRIQ, la Dynagrade de Dynalyse AB et la XLG de Coe Mfg.
This report summarises the work accomplished in this one-year project in which the fire performance of wood-frame buildings was to be documented. A detailed analysis of Canadian and American fire loss statistics for residential occupancies was undertaken in order to assess the impact of the choice of building materials and the nature of fire-safety provisions in building codes on the overall fire safety in buildings. It was expected that the knowledge gained would enable the wood industry to argue more effectively during deliberations of codes and standards committees.
This study demonstrated that buildings constructed in compliance with current North American building code requirements are among the safest in the world. It was found that the fire loss record of wood-frame houses is about the same as that of large apartment buildings of non-combustible construction. It was shown that the ignition of upholstered furniture or mattresses by smokers’ materials is far and away the leading cause of residential fires involving deaths. Most of these deaths occur before the structure of the building becomes damaged by or involved in fire. Enacting more stringent building code requirements is unlikely to pay a large dividend in terms of life safety. In fact, the statistics suggest that significant improvements in fire safety in buildings would be more easily achieved by limiting the flammability of upholstered furniture and mattresses.
A system which integrates architectural and structural design issues for timber connections will be developed for a limited number of connections and loading conditions which are dealt with in various national and international codes and standards. The scope of engineering issues relevant to connections will be expanded to include a wide range of timber connections and engineering solutions which are not covered by code procedures. This will include cases such as 3-dimensional loading configurations, dynamic analysis of connections and more rigorous analysis procedures. Progress on these objectives is described.
