The objective of the current project is to develop a performance-based design process for wood-based design systems that would meet the objectives and functional statements set forth in the National Building Code of Canada. More specifically, this report discusses the fire and seismic performance of buildings, as identified as a priority in a previous FPInnovations report (Dagenais, C. (2016). Development of Performance Criteria for Wood-Based Building Systems).
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.
FPInnovations carried out a survey with consultants and researchers on the use of analytical models and software packages related to the analysis and design of mass timber buildings. The responses confirmed that a lack of suitable models and related information for material properties of timber connections was creating an impediment to the design and construction of this type of buildings. Furthermore, there is currently a lack of computer models and expertise for carrying out performance-based design for wood buildings, in particular seismic and/or fire performance design.
In this study, a sophisticated constitutive model for wood-based composite material under stress and temperature was developed. This constitutive model was programmed into a user-subroutine which can be added to most general-purpose finite element software. The developed model was validated with test results of a laminated veneer lumber (LVL) beam and glulam bolted connection under force and/or fire.
During the past few years, a relatively new technology has emerged in North America and changed the way professionals design and build wood structures: Cross-laminated Timber (CLT). CLT panels are manufactured in width ranging from 600 mm to 3 m. As such, fastening them together along their major strength axis is required in order to form a singular structural assembly resisting to in-plane and out-of-plane loading. Typical panel-to-panel joint details of CLT assemblies may consist of internal spline(s), single or double surface splines or half-lapped joints. These tightly fitted joint profiles should provide sufficient fire-resistance, but have yet to be properly evaluated for fire-resistance in CLT assemblies.
The experimental portion of the study consisted at conducting ten (10) intermediate-scale fire-resistance tests of CLT floor assemblies with four (4) types of panel-to-panel joints and three (3) CLT thicknesses. The data generated from the intermediate-scale fire tests were used to validate a finite element heat transfer model, a coupled thermal-structural model and a simplified design model. The latter is an easy-to-use design procedure for evaluating the fire integrity resistance of the four commonly-used CLT floor assemblies and could potentially be implemented into building codes and design standards. Based on the test data and models developed in this study, joint coefficient values were derived for the four (4) types of CLT panel-to-panel joint details. Joint coefficients are required when assessing the fire integrity of joints using simple design models, such as the one presented herein and inspired from Eurocode 5: Part 1-2.
The contribution of this study is to increase the knowledge of CLT exposed to fire and to facilitate its use in Canada and US by complementing current fire-resistance design methodologies of CLT assemblies, namely with respect to the fire integrity criterion. Being used as floor and wall assemblies, designers should be capable to accurately verify both the load-bearing and separating functions of CLT assemblies in accordance with fire-related provisions of the building codes, which are now feasible based on the findings of this study.
FPInnovations initiated this project to demonstrate the ability of wood exit stairs in mid-rise buildings to perform adequately in a fire when NBCC requirements are followed, with the intent of changing perceptions of the fire safety of wood construction. The objective of this research is to investigate further the fire safety afforded by exit stair shafts of combustible construction, with the ultimate objective of better consistency between the provincial and national building codes with respect to fire requirements for exit stair shafts in mid-rise wood-frame construction.
Sustainable, safe, durable, cost-effective and efficient; wood is used across Canada in occupancy classes such as business, residential, commercial and assembly. In the United States, many mixed-use buildings have been designed as “podium” buildings; a wood structure bearing on a podium of noncombustible construction. The International Building Code includes provisions that allow wood buildings, often housing residential or business occupancies, to be constructed over a podium of noncombustible construction accommodating mercantile or assembly occupancies.
The concept of a horizontal fire separation, acting to a certain degree as a “horizontal firewall”, was introduced in the International Building Code in the mid-2000s, allowing the podium to be considered a separate and distinct building from the wood structure that sits overtop. Since podium structures are becoming increasingly “à la mode” in the construction industry, integrating the horizontal fire separation concept into the National Building Code of Canada would allow the industry to benefit from the advantages of wood construction in mixed-use buildings
At the request of FPInnovations, this technical report has been prepared as a guideline for the implementation of design provisions for wood podium buildings into the National Building Code of Canada. Various strategies, special considerations, and possible risks for fire safety in this type of building are explored.
The main objective of this study is to evaluate the heat release rate and fire growth contribution due to heat delamination characteristics of CLT manufactured with four types of adhesives used for face bonding, when exposed to a constant radiant heat flux. The evaluation is performed using the principles of ISO 5660-1 “Reaction-to-fire tests - Heat release, smoke production and mass loss rate – Part 1: Heat release rate (cone calorimeter method)”. The American version of this test method is ASTM E1354 « Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter ».
The long-term objective is to determine which currently accepted test methods allow for the most suitable evaluation of heat delamination characteristics of adhesives used in structural engineered wood products, based on their actual end-use applications (e.g. bending, compression, combined stress, cross-plies, etc.).
Recent architectural trends include the design and construction of increasingly tall buildings with structural components comprised of engineered wood referred to by names including; cross laminated timber (CLT), laminated veneer lumber (LVL), or glued laminated timber (Glulam). These buildings are cited for their advantages in sustainability resulting from the use of wood as a renewable construction material. Previous research has shown that timber elements contribute to the fuel load in buildings and can increase the initial fire growth rate – potentially overwhelming fire protection system and creating more severe conditions for occupants, emergency responders, and nearby properties.
The overarching goal of this project Fire Safety Challenges of Tall Wood Buildings Phase 2 (involving five tasks) is to quantify the contribution of CLT building elements (wall and/or floor-ceiling assemblies) in compartment fires and provide data to allow comparison of the performance of CLT systems against other building systems commonly used in tall buildings.