Timber buildings made with Cross-laminated Timber (CLT) panels are becoming wide spread in Europe. The fire resistance of CLT panels depends upon several parameters, including the number of layers and their thickness. At the present, EN 1995-1-2:2004 does not provide specific information on the fire design of CLT panels. Several fire resistance tests of CLT panels were performed in different scales by furnace testing using the standard fire curve according to ISO 834-1:1999, however the large number of possible combination of CLT products makes testing too complicated and expensive as a tool for the verification of the fire resistance of several combinations. In this report are presented nine small-scale tests carried-out at SP Wood Technology (Technical Research Institute of Sweden). The tests consisted in specimens of CLT and massive timber exposed at a two steps of constant heat flux in a cone calorimeter (50 and 75 kW/m2). Some specimens were exposed with two different types of fire protection (gypsum plasterboard type F and plywood) and some were tested unprotected. Later, thermal simulations with the same set-up of tests were implemented on the finite element software package in Safir 2007, with the time-temperature curve given by ISO 834 as input; also the analytical calculation of the charring depth following the Eurocode 5 part 1-2 was done. The target of this thesis is to compare performed CLT furnace tests with the smallscale cone calorimeter tests carried out, the numerical results of the thermal model and the analytical results obtained.
An experimental study was conducted to elucidate the effects of thermal penetration on delamination and the potential changes in failure mode of CLT. The first test series studied thermal penetration depths at various heat fluxes. The second test series consisted of single lap shear tests at homogeneous elevated temperatures followed by a...
A large-scale fire test was conducted on a compartment constructed from cross laminated timber (CLT). The internal faces of the compartment were lined with non-combustible board, with the exception of one wall and the ceiling where the CLT was exposed directly to the fire inside the compartment. Extinction of the fire occurred without intervention. During the fire test, measurements were made of incident radiant heat flux, gas phase temperature, and in-depth temperature in the CLT. In addition, gas flow velocities and gas phase temperatures at the opening were measured, as well as incident heat fluxes at the facade due to flames and the plume leaving the opening. The fuel load was chosen to be sufficient to attain flashover, to achieve steadystate burning conditions of the exposed CLT, but to minimize the probability of uncertain behaviors induced by the specific characteristics of the CLT. Ventilation conditions were chosen to approximate maximum temperatures within a compartment. Wood cribs were used as fuel and, following decay of the cribs, selfextinction of the exposed CLT rapidly occurred. In parallel with the large-scale test, a small scale study focusing on CLT self-extinction was conducted. This study was used: to establish the range of incident heat fluxes for which self-extinction of the CLT can occur; the duration of exposure after which steady-state burning occurred; and the duration of exposure at which debonding of the CLT could occur. The large-scale test is described, and the results from both the small and large-scale tests are compared. It is found that selfextinction occurred in the large-scale compartment within the range of critical heat fluxes obtained from the small scale tests.
Project contact is Christian Dagenais at Université Laval
The use of materials in a building is traditionally determined from its combustibility (via ULC S114 or ULC S135) and by its flame propagation index (via ULC S102). The ULC S102 Flame Spread Test, developed in 1943, has historically reduced risk through its method of classifying materials. However, this test does not provide quantitative information on the combustion properties of materials, such as heat flow. The latter is one of the most important variables in the development of a fire. Thus, a new approach would be preferable in order to review the classification of materials according to ULC S102 and ULC S135 (cone calorimeter). The objective of this project is to develop a new approach to classifying materials based on cone calorimeter test results. These results can subsequently be used in numerical modeling as part of a fire safety engineering design. A significant amount of cone calorimeter (ULC S135) testing of materials currently evaluated according to ULC S102 will be required.
Cross-laminated timber (CLT) is a popular construction material for low and medium-rise construction. However an architectural aspiration exists for tall mass timber buildings, and this is currently hindered by knowledge gaps and perceptions regarding the fire behaviour of mass timber buildings. To begin to address some of the important questions regarding the structural response of fire-exposed CLT structures in real fires, this paper presents a series of novel fire tests on CLT beams subjected to sustained flexural loading, coincident with non-standard heating using an incident heat flux sufficient to cause continuous flaming combustion. The load bearing capacities and measured time histories of deflection during heating are compared against predicted responses wherein the experimentally measured char depths are used, along with the Eurocode recommended reduced cross section method and zero-strength layer thickness. The results confirm that the current zero-strength layer value (indeed the zero-strength concept) fails to capture the necessary physics for robust prediction of structural response under non-standard heating. It is recommended that more detailed thermo-mechanical cross-sectional analyses, which allow the structural implications of real fire exposures to be properly considered, should be developed and that the zero-strength layer concept should be discarded in these situations. Such a novel approach, once developed and suitably validated, could offer more realistic and robust structural fire safety design.