The key objective of this study is to analyze full-scale fire-resistance tests conducted on structural composite lumber (SCL), namely laminated veneer lumber (LVL), parallel strand lumber (PSL) and laminated strand lumber (LSL). A sub-objective is to evaluate the encapsulation performance of Type X gypsum board directly applied to SCL beams and its contribution to fire-resistance of wood elements.
The test data is being used to further support the applicability of the newly developed Canadian calculation method for mass timber elements, recently implemented as Annex B of CSA O86-14.
The report concludes with the recommendation that it would be useful to run an extensive set of cone calorimeter tests on SCL, glue-laminated timber and CLT products. The fundamental data could be most useful for validating models for predicting flame spread ratings of massive timber products and useful as input to comprehensive computer fire models that predict the course of fire in buildings. It is also argued that the cone calorimeter would be a useful tool in assessing fire performance during product development and for quality control purposes.
The present work aims at evaluating the combustibility characteristics (i.e. reaction to fire) of structural composite lumber (SCL) when tested in compliance with the cone calorimeter standard ISO 5660 [7, 8, 9]. More precisely, this study evaluates the heat release rate, total heat release, mass loss, effective heat of combustion, smoke obscuration as well as the presence of toxic gases when SCL products are tested in conformance with ISO 5660.
Moreover, this study is solely focused on SCL elements that are thick enough to act as semi-infinite solids (thermally thick solids), as opposed to typical thin combustible finish products. Tests data are also compared to those obtained for visually-graded solid wood specimens of the SPF species group.
Combustibility
Composite Lumber
Laminated products - Fire resistance
Structural Composites - Properties
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These tests were performed to support the approval and construction of a tall wood building in Quebec City (13-storey). While a calculation methodology is provided in Chapter 8 (Fire) of the CLT Handbook [3], the Association des Chefs en Sécurité Incendie du Québec (ACSIQ), the Régie du bâtiment du Québec (RBQ) and other stakeholders requested these tests be performed so that they could witness the actual fire performance of the specified assemblies. As such, the main objective was to demonstrate at least a 2 h FRR of the CLT assemblies, which is the minimum required rating as prescribed by the National Building Code of Canada [4] for structural elements and fire separation walls of exit stair ways and elevators shafts in tall buildings (greater than 6 storeys).
Numerous representatives from Quebec and Ontario were present for either one or both days of testing, including RBQ, the Cities of Montreal, Ottawa, and Quebec City as well as fire services personnel from Montreal, Ottawa and Gatineau. FPInnovations, Nordic, the Canadian Wood Council (CWC), and CHM fire consultants were also in attendance.
Le bois lamellé-croisé (CLT), un système de construction relativement récent pour lequel l’intérêt ne cesse de croître dans le secteur de la construction d’Amérique du Nord, contribue à la définition d’une nouvelle classe de produits massifs en bois. Le CLT est un composant structural à base de bois très prometteur, qui présente un potentiel élevé pour fournir des solutions de construction rentables pour les bâtiments résidentiels, commerciaux et institutionnels ainsi que pour les grandes installations industrielles. L’acceptation de la construction en CLT dans l’environnement réglementaire canadien requiert la conformité aux dispositions relatives à la protection incendie du Code national du bâtiment du Canada (CNBC), entre autres choses.
Des essais au feu approfondis ont démontré la capacité du CLT à fournir un degré de résistance au feu pouvant atteindre près de 3 heures lorsque le matériau est mis à l’essai dans des conditions de plein chargement conformément à la norme CAN/ULC S101. De plus amples renseignements sont également fournis sur les propriétés de sécurité incendie connexes, y compris l’indice de propagation des flammes et les dispositifs coupe-feu.
Les éléments de CLT sont utilisés dans les systèmes de construction d’une façon similaire aux dalles de béton et aux éléments muraux massifs ainsi qu’aux éléments utilisés dans la construction en gros bois d’œuvre en limitant les vides de construction créés grâce à l’utilisation des éléments massifs en bois, ce qui contribue à réduire le risque d’incendies dans ces vides de construction. En outre, la construction en CLT utilise généralement des panneaux de CLT pour les planchers et les murs porteurs, ce qui permet d’obtenir une compartimentation ayant une résistance inhérente au feu et contribue une fois de plus à réduire le risque de la propagation d’un incendie au-delà de son point d’origine (compartiment d’origine).
Le présent document propose une méthodologie visant à déterminer la résistance au feu des éléments de CLT. En tant que modèle déterministe fondé sur les concept de calculs aux états limites, cette méthode permet de calculer la résistance des éléments de CLT soumis à une exposition au feu standard (soit la norme CAN/ULC S101) à l’aide des mécanismes techniques de base du bois pour les calculs de résistance au feu allant jusqu’à 3 heures, qui ne sont limités que par la disponibilité actuelle des données. La méthode utilise un ajustement linéaire échelonné de la vitesse de carbonisation, une épaisseur de la couche carbonisée de 7 mm dont la résistance et la rigidité sont supposées nulles, un coefficient de résistance égal à l’unité, un coefficient de durée d’application de la charge de courte durée, et des résistances spécifiées ajustées à leurs valeurs moyennes pour prédire les temps moyens de résistance au feu des éléments de murs et planchers de CLT qui suivent étroitement les temps réels de résistance au feu des éléments testés. Bien que certaines améliorations à cette méthode soient encore possibles, ces comparaisons suggèrent que la méthodologie prédit de façon prudente la résistance au feu des éléments de CLT.
Cross-laminated timber (CLT) panels have the potential to provide excellent fire resistance often comparable to typical massive assemblies of non-combustible construction. Due to the inherent nature of thick timber members to slowly char at a predictable rate, massive wood systems can maintain significant structural capacity for extended durations when exposed to fire.
In order to facilitate the acceptance of future code provisions for the design of CLT panels for fire resistance, a one-year research project was launched at FPInnovations in April 2010. The main objective of the project is to develop and validate a generic procedure to calculate the fire-resistance ratings of CLT wall and floor assemblies. A series of full-scale fire-resistance experiments is currently under way to allow a comparison between the fire resistance rating measured during a standard fire-resistance test and that calculated using the proposed procedure.
In light of the fact that the research project is just beginning, a simple but conservative design procedure is presented in this chapter, following the current state-of-the-art information from Europe and North America. The Canadian Standard for Engineering Design in Wood (CSA O86) can be used to calculate the fire-resistance rating of CLT panels along with the same methodology that is currently used for calculating the fire-resistance ratings of glued-laminated timber and “heavy” timber in the United States, New Zealand and Europe. This method is called the reduced (or effective) cross-section method and allows the use of the design values that can be found in CSA O86. It is recommended that a qualified fire protection engineer undertake or oversee the design of CLT assemblies for fire resistance. The fire protection engineer should work closely with the structural engineer so that the implications of fire exposure to the structural design are considered.
The main objective of this study is to evaluate the fire-protection F- and T-ratings of selected fire stops and sealing joints in cross-laminated timber assemblies, in accordance with CAN/ULC S115 test method, “Standard Method of Fire-Tests of Firestop System”.
Recommendations are given in this report with respect to proper detailing to ensure that the tested closure devices, when used in mass timber plate construction, will perform as expected. It is noted that test data is to date limited, and further testing may result in revision of these recommendations.
Glulam and CLT innovative manufacturing process and products development : effects of manufacturing parameters on the fire-resistance of CLT assemblies
This study was part of a broader project entitled Glulam and CLT Innovative Manufacturing Process and Product Development. The main objective of the current study is to evaluate the effect of CLT panels manufacturing parameters on its fire resistance. More specifically:
§ To evaluate the effect of CLT manufacturing (gluing) parameters on the heat delamination resistance under standard fire conditions;
§ To improve the fire-resistance of the CLT panels.
