Building elements are required to provide sufficient fire resistance based on requirements set forth in the National Building Code of Canada (NBCC). Annex B of the Canadian standard for wood engineering design (CSA O86-19) provides a design methodology to calculate the structural fire-resistance of large cross-section timber elements. However, it lacks at providing design provisions for connections. The objectives of this study are to understand the fire performance of modern mass timber fasteners such as self-tapping screws, namely to evaluate their thermo-mechanical behavior and to predict their structural fire-resistance for standard fire exposure up to two hours, as would be required for tall buildings in Canada. The results present the great fire performance of using self-tapping screws under a long time exposure on connections in mass timber construction. The smaller heated area of the exposed surface has limited thermal conduction along the fastener’s shanks and maintained their temperature profiles relatively low for two hours of exposure. Based on the heat-affected area, the study presents new design principles to determine the residual length of penetration that would provide adequate load-capacity of the fastener under fire conditions. It also allows determining safe fire-resistance values for unprotected fasteners in mass timber construction exposed up to two hours of standard fire exposure.
Fire safety regulations impose very strict requirements on building design, especially for buildings built with combustible materials. It is believed that it is possible to improve the management of these regulations with a better integration of fire protection aspects in the building information modeling (BIM) approach. A new BIM-based domain is emerging, the automated code checking, with its growing number of dedicated approaches. However, only very few of these works have been dedicated to managing the compliance to fire safety regulations in timber buildings. In this paper, the applicability to fire safety in the Canadian context is studied by constituting and executing a complete method from the regulations text through code-checking construction to result analysis. A design science approach is used to propose a code-checking method with a detailed analysis of the National Building Code of Canada (NBCC) in order to obtain the required information. The method starts by retrieving information from the regulation text, leading to a compliance check of an architectural building model. Then, the method is tested on a set of fire safety regulations and validated on a building model from a real project. The selected fire safety rules set a solid basis for further development of checking rules for the field of fire safety. This study shows that the main challenges for rule checking are the modeling standards and the elements’ required levels of detail. The implementation of the method was successful for geometrical as well as non-geometrical requirements, although further work is needed for more advanced geometrical studies, such as sprinkler or fire dampers positioning.
Air leaks have a considerable impact on the energy load and durability of buildings, particularly in cold climates. In wood construction using cross-laminated timber (CLT), air leaks are most likely to be concentrated at the joints between panels and other elements. This study used simulations of heat, air, and moisture transfers through a gap between two CLT panels causing air leakage in winter conditions under a cold climate. A real leakage occurrence was sized to validate the simulations. The aim of this work was to assess the impact on the energy loads and the durability of an air leak, as either infiltration or exfiltration, for different gap widths and relative humidity levels. The results showed that infiltrations had a greater impact on the energy load than exfiltrations but did not pose a threat to the durability, as opposed to exfiltrations. Gap sizes in CLT may vary, but the effect on the energy load was sensitive to the leakage path in the rest of the wall. As expected, a combination of winter exfiltration and a high level of interior relative humidity was particularly detrimental.