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Structural Response of Cross-Laminated Timber Compression Elements Exposed to Fire

https://research.thinkwood.com/en/permalink/catalogue1338
Year of Publication
2017
Topic
Fire
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Wiesner, Felix
Randmael, Fredrik
Wan, Wing
Bisby, Luke
Hadden, Rory
Publisher
ScienceDirect
Year of Publication
2017
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Fire
Mechanical Properties
Keywords
Reduced Cross-Section Method
Axial Load
Compressive Load
Deformation
Temperature
Zero-Strength Layer
Language
English
Research Status
Complete
Series
Fire Safety Journal
Summary
A set of novel structural fire tests on axially loaded cross-laminated timber (CLT) compression elements (walls), locally exposed to thermal radiation sufficient to cause sustained flaming combustion, are presented and discussed. Test specimens were subjected to a sustained compressive load, equivalent to 10 % or 20 % of their nominal ambient axial compressive capacity. The walls were then locally exposed to a nominal constant incident heat flux of 50 kW/m2 over their mid height area until failure occurred. The axial and lateral deformations of the walls were measured and compared against predictions calculated using a finite Bernoulli beam element analysis, to shed light on the fundamental mechanics and needs for rational structural design of CLT compression elements in fire. For the walls tested herein, failure at both ambient and elevated temperature was due to global buckling. At high temperature failure results from excessive lateral deflections and second order flexural effects due to reductions the walls’ effective crosssection and flexural rigidity, as well as a shift of the effective neutral axis in bending during fire. Measured average one-dimensional charring rates ranged between 0.82 and 1.0 mm/min in these tests. As expected, the lamellae configuration greatly influenced the walls’ deformation responses and times to failure; with 3- ply walls failing earlier than those with 5-plies. The walls’ deformation response during heating suggests that, if a conventional reduced cross section method (RCSM), zero strength layer analysis were undertaken, the required zero strength layer depths would range between 15.2 mm and 21.8 mm. Deflection paths further suggest that the concept of a zero strength layer is inadequate for properly capturing the mechanical response of fire-exposed CLT compression elements.
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Fire Testing of Rooms with Exposed Wood Surfaces in Encapsulated Mass Timber Construction

https://research.thinkwood.com/en/permalink/catalogue1867
Year of Publication
2018
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Su, Joseph
Leroux, Patrice
Lafrance, Pier-Simon
Berzins, Robert
Gibbs, Eric
Weinfurter, Mark
Organization
National Research Council of Canada
Publisher
National Research Council Canada. Construction
Year of Publication
2018
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Keywords
Encapsulated
Mass Timber
Fire Tests
Fire Performance
Char Layer
Fire Regrowth
Language
English
Research Status
Complete
Series
Client Report (National Research Council Canada. Construction)
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Free
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Reliability of Timber Elements Exposed to Fire

https://research.thinkwood.com/en/permalink/catalogue1675
Year of Publication
2016
Topic
Fire
Material
Glulam (Glue-Laminated Timber)
Author
Lange, David
Boström, Lars
Schmid, Joachim
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Fire
Keywords
Reliability
First Order Reliability Method
Eurocode
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3906-3915
Summary
This paper discusses the principles of performance based structural design and motivates the need for probabilistic assessment of the response of structures and an assessment of the consequences of failure. Using the results from a series of tests carried out at SP in Sweden, we extrapolate data required for the assessment of timber structures under a range of parametric fires. This data also includes information required to develop probabilistic models of the response of timber elements under different parametric fires. Using methodologies from the literature, we then carry out a reliability analysis of timber structures, considering uncertainties the timber response to fire. This is carried out using the first order reliability method. We show that the opening factor has an influence on the reliability of timber structures, as a result of the rate of heating in a parametric fire exposure. A minimum reliability, evolving over time, is seen to occur at an opening factor of 0.14m 1/2. Finally, we propose a modification to the Eurocode target reliability indices that allows these to be used as a target reliability index for structures exposed to fire. The proposed modification is dependent on the floor area and the method is exemplified here for a range of floor areas and its application to timber structures is illustrated.
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Structural Response of Fire-Exposed Cross-Laminated Timber Beams under Sustained Loads

https://research.thinkwood.com/en/permalink/catalogue1364
Year of Publication
2016
Topic
Fire
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Lineham, Sean
Thomson, Daniel
Bartlett, Alastair
Bisby, Luke
Hadden, Rory
Publisher
ScienceDirect
Year of Publication
2016
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Fire
Mechanical Properties
Keywords
Flexural Loading
Reduced Cross-Section Method
Zero-Strength Layer
Char Depth
Eurocode
Load Bearing Capacity
Deflection
Heat Flux
Language
English
Research Status
Complete
Series
Fire Safety Journal
Summary
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.
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Effects of Exposed Cross Laminated Timber on Compartment Fire Dynamics

https://research.thinkwood.com/en/permalink/catalogue1340
Year of Publication
2017
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Rooms
Author
Hadden, Rory
Bartlett, Alastair
Hidalgo, Juan
Santamaria, Simón
Wiesner, Felix
Bisby, Luke
Deeny, Susan
Lane, Barbara
Publisher
ScienceDirect
Year of Publication
2017
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Rooms
Topic
Fire
Keywords
Compartment Fires
Heat Release Rate
Temperature
Exposed Timber
Auto-Extinction
Combustible Material
Heat Transfer
Language
English
Research Status
Complete
Series
Fire Safety Journal
Summary
A series of compartment fire experiments has been undertaken to evaluate the impact of combustible cross laminated timber linings on the compartment fire behaviour. Compartment heat release rates and temperatures are reported for three configuration of exposed timber surfaces. Auto-extinction of the compartment was observed in one case but this was not observed when the experiment was repeated under identical condition. This highlights the strong interaction between the exposed combustible material and the resulting fire dynamics. For large areas of exposed timber linings heat transfer within the compartment dominates and prevents auto-extinction. A framework is presented based on the relative durations of the thermal penetration time of a timber layer and compartment fire duration to account for the observed differences in fire dynamics. This analysis shows that fall-off of the charred timber layers is a key contributor to whether auto-extinction can be achieved.
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Residual Compressive Load-Carrying Capacity of Cross-Laminated Timber Walls After Exposed to One-Side Fire

https://research.thinkwood.com/en/permalink/catalogue2689
Year of Publication
2020
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Bai, Yu
Zhang, Jin
Shen, Hao
Publisher
Elsevier
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Fire
Keywords
Residual Compressive Load-carrying Capacity
Fire Test
One-side Fire
Axial Compression Tests
Language
English
Research Status
Complete
Series
Journal of Building Engineering
Summary
Cross-laminated timber (CLT) panels are broadly utilized as structural members in modern timber structures. Variation in the residual resistance of CLT walls after fire exposure may lead to disruption of vertical force transmission and, in turn, structural collapse. To investigate the residual compressive load-carrying capacity of CLT walls after exposed to one-side fire, a series of tests were conducted on 3-ply and 5-ply members: axial compression tests, fire tests, and residual compressive load-carrying capacity tests. Combining the initial geometric defects obtained from the test results and the effect of shear deformation, theoretical formulae describing the compressive load-carrying capacity were deduced. Further considering the different mechanical properties over the residual cross-section model after fire, and the relative position between Region A and CLT orthogonal configuration, the calculation method of the residual compressive load-carrying capacity after fire were derived. The results of the residual compressive load-carrying capacity tests showed that the failure mode of the CLT walls after one-side fire was the eccentric compression, and the nonlinear segments of the load-axial and load-lateral displacement curves after fire accounted for larger proportion than those of axial compression tests. For the same total section thickness, the reduction in residual capacity of the 5-ply walls after fire was less than that of the 3-ply walls. The calculation results of the eccentric compression formulae considering shear deformation and initial geometric defect showed good agreement with the test values of axial compression tests. The residual compressive load-carrying capacity after one-side fire was predicted appropriately, which could be used as reference for assessing the residual load-carrying behavior of CLT elements after fire.
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Structural Capacity of One-Way Spanning Large-Scale Cross-Laminated Timber Slabs in Standard and Natural Fires

https://research.thinkwood.com/en/permalink/catalogue2734
Year of Publication
2020
Topic
Fire
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Wiesner, Felix
Bartlett, Alastair
Mohaine, Siyimane
Robert, Fabienne
McNamee, Robert
Mindeguia, Jean-Christophe
Bisby, Luke
Publisher
Springer
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Mechanical Properties
Keywords
Deflection
Temperature
Load Bearing Capacity
Ventilation
Fire Safety
Language
English
Research Status
Complete
Series
Fire Technology
Summary
This paper describes selected observations, measurements, and analysis from a series of large-scale experiments on cross-laminated timber (CLT) slabs that were exposed to fire from below, using four different heating scenarios, with a sustained mechanical loading of 6.3 kN m per metre width of slab. The deflection response and in-depth timber temperatures are used to compare the experimental response against a relatively simple structural fire model to assess the load bearing capacity of CLT elements in fire, including during the decay phase of natural fires. It is demonstrated that the ventilation conditions in experiments with a fixed fuel load are important in achieving burnout of the contents before structural collapse occurs. A mechanics-based structural fire model is shown to provide reasonably accurate predictions of structural failure (or lack thereof) for the experiments presented herein. The results confirm the importance of the ventilation conditions on the fire dynamics, burning duration, and the achievement of functional fire safety objectives (i.e. maintaining stability and compartmentation), in compartments with exposed CLT.
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Fire Safety of Bonded Structural Timber Elements

https://research.thinkwood.com/en/permalink/catalogue1139
Year of Publication
2014
Topic
Fire
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Klippel, Michael
Organization
ETH Zurich
Year of Publication
2014
Country of Publication
Switzerland
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Topic
Fire
Connections
Keywords
Finger-Jointed
Adhesives
Fire Resistance
Europe
Zero-Strength Layer
Language
German
Research Status
Complete
Summary
The development of polyurethane (PUR) adhesives for engineered wood products started in Switzerland in 1985. Those adhesives satisfied the need for formaldehyde free adhesives, which is mainly attributed to health and environmental reasons. However, due to new requirements concerning the high temperature resistance of adhesives, especially in North America, newly developed adhesives are basically banned from the market, and adhesive manufacturers face a new barrier to approve their new adhesive technologies on the market. The work presented in this thesis clarifies the influence of adhesives on the fire design of glued-laminated timber beams. Additionally, clear scientifically based requirements are identified, which should be met by adhesives used in glued-laminated timber beams in case of fire. In this thesis, twelve different adhesives for both structural and non-structural applications were tested in large-scale fire tests on finger-jointed timber lamellas. Those fire tests indicated that structural adhesives certified according to current European testing standards exhibit sufficient strength in fire for the use in glued-laminated timber beams. Taking into account the crack pattern observed in the fire tests, no significant influence on the fire resistance was found between the studied structural adhesives. Therefore, it is not necessary to consider the influence of adhesives in the design of glued-laminated timber beams, given that the adhesive is approved according to current European testing standards.
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Behaviours of Larch Glued Laminated Timber Beams Exposed to Standard Fire Heating During the Cooling Phase Study on Fire Performance of Structural Glued Laminated Timber Beams Part 1

https://research.thinkwood.com/en/permalink/catalogue1112
Year of Publication
2015
Topic
Fire
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Kanjo, Hinjin
Hidemasa, Yusa
Horio, Takehito
Hirashima, Takeo
Takumi, Matsumoto
Saito, Kiyoshi
Publisher
J-STAGE
Year of Publication
2015
Country of Publication
Japan
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Fire
Keywords
Larch
Load Bearing Capacity
Charring Rate
Cooling
Language
Japanese
Research Status
Complete
Series
Architectural Institute of Japan Structural System
ISSN
1881-8153
Summary
Timber elements, which are different from other structural elements, have a characteristic problem in that the load bearing capacity decreases due to self-burning in the case of a fire, and this self-burning may continue after other fuel in the room has been exhausted. Therefore, the structural fire performance of timber elements should be clarified during not only the heating phase, but also the cooling phase. However, in examining the load bearing capacity of timber elements in a fire, few studies have considered the cooling phase. In the present paper, the fire performance of glued, laminated timber beams is discussed based on load-bearing fire tests that take the cooling phase into consideration.
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The Fire Performance of Exposed Timber Panels

https://research.thinkwood.com/en/permalink/catalogue146
Year of Publication
2014
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Wong, Bernice
Tee, Kong Fah
Publisher
World Academy of Science, Engineering and Technology
Year of Publication
2014
Country of Publication
United Kingdom
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
High-Rise
Charring Rate
Temperature
Eurocode
Language
English
Research Status
Complete
Series
International Journal of Civil and Environmental Engineering
Summary
Cross-laminated timber is increasingly being used in the construction of high-rise buildings due to its simple manufacturing system. In term of fire resistance, cross-laminated timber panels are promoted as having excellent fire resistance, comparable to that of non-combustible materials and to heavy timber construction, due to the ability of thick wood assemblies to char slowly at a predictable rate while maintaining most of their strength during the fire exposure. This paper presents an overview of fire performance of cross-laminated timber and evaluation of its resistance to elevated temperature in comparison to homogeneous timber panels. Charring rates for cross-laminated timber panels of those obtained experimentally were compared with those provided by Eurocode simplified calculation methods. Keywords—Timber structure, cross-laminated timber, charring rate, timber fire resistance.
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10 records – page 1 of 1.