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.
In this project, CUrisk was employed to assess and compare the risk-to-life due to fire in mid-rise and high-rise residential and office buildings of wood construction and of non-combustible construction and to demonstrate how fire protection measures can be tuned to ensure a mid-rise or high-rise building of wood construction is as safe as a similar building of non-combustible construction.
The computation results show that [...] Comparisons between the numbers of deaths and injuries of scenarios with and without suitable fire protection systems show the importance of fire protection systems in reducing life risk from fire in all buildings. Sustaining the reliability of fire protection systems through proper design, installation, inspection, and maintenance is important to achieve the life safety objectives.
This study assesses the seismic performance of a new hybrid timber-steel moment-resisting connection for mid-rise heavy timber structures. This system consists predominantly of timber members, but utilizes a steel yielding link at the beam-column joint that improves seismic performance by replacing connection components that are susceptible to brittle failure with ductile steel elements. The steel-to-timber connection was made using self-tapping screws. By localizing all inelastic behaviour to a single ductile component, design with high seismic force reduction factors becomes justifiable. Four connections were tested; a majority of the plastic rotation was localized to the link, high levels of ductility were achieved, and the steel-to-timber connections remained undamaged. A numerical study was performed on a hybrid frame using the proposed connection, and an equivalent steel-only frame. Results showed that drifts and accelerations remained within allowable limits, indicating that well-detailed hybrid connections can result in seismic performance similar to steel-only frames.
Presented in this paper are the results of an experimental program investigating the out-of-plane behavior of CLT panels under static and blast loading. A total of 18 CLT panels, with panel thicknesses of 105 and 175 mm corresponding to a 3-ply and 5-ply panel, respectively, were investigated with the aim to determine the dynamic increase factor (DIF). An average dynamic increase factor of 1.28 on the resistance and no apparent increase in stiffness from static to dynamic loading were observed. Two resistance material predictive models that account for high strain-rate effects and the experimentally observed post-peak residual behavior were developed. A single-degree-of-freedom model was validated using full-scale simulated blast load tests, and the predictions were found to match well with the experimental displacement-time histories.
This study which involves the development of fire loads and design fires for residential and non-residential mid-rise buildings is part of NEWBuildS’ “Rationalization o f Life Safety - Code Requirements fo r Mid-rise Buildings” project. The project is focused on analysing the code requirements that relate to fire resistance and the use of automatic sprinklers for mid-rise buildings built with combustible or non-combustible construction. The ultimate goal of the project is to come up with alternative solutions and, potentially, trigger changes in the code requirements for mid-rise buildings.
A review, compilation, and analysis of fire load survey data was conducted from available literature for residential and office buildings. A web survey of floor areas was also conducted for floor areas of mid-rise buildings. Fire loads and fuel packages for midrise buildings were developed based on previous surveys as well as the web survey. The fire load data in conjunction with statistical data was used to select fire scenarios from which design fire scenarios were chosen.
The fire characteristics of the selected fuel packages, such as heat release rate, and production of toxic gases, were analyzed using the two-zone fire risk analysis model, CUrisk, in order to develop appropriate design fires for mid-rise buildings.
This thesis studies the fire behaviour of Cross Laminated Timber (CLT) panels in partially protected rooms. A one-dimensional heat transfer model was developed to determine the fire resistance of CLT floor and wall panels. During this study, three room fire tests were conducted at Carleton University Fire Research Laboratory to determine the maximum percentage of unprotected CLT surface area that will yield similar results to that of a fully protected room. The rooms had a single opening and were constructed entirely using 3-ply, 105 mm thick CLT panels. A non-standard, parametric fire using furniture and clothing as fuel was used and 2 layers of gypsum board were used to cover the ceiling and the protected walls. The Heat Release Rate, temperature, charring rate and gypsum falloff time of each test was collected. The results obtained from the room test were then compared to the numerical heat transfer model to evaluate its accuracy.
