Structural response of cross-laminated timber compression elements exposed to fire

Wiesner, Felix; Randmael, Fredrik; Wan, Wing; Bisby, Luke; Hadden, Rory M.

doi:10.1016/j.firesaf.2017.05.010

Cited by 36 publications

(13 citation statements)

References 19 publications

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“…These results agree with the literature. Wiesner et al [50] exposed timber walls to a constant heat flux and found zero-strength layers between 15 and 22 mm. Schmid et al exposed timber to the standard fire and found zero-strength layers of up 19 mm.…”

Section: Discussion On Zero-strength Layermentioning

confidence: 99%

Thermal Response of Timber Slabs Exposed to Travelling Fires and Traditional Design Fires

et al. 2020

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Engineered timber is an innovative and sustainable construction material, but its uptake has been hindered by concerns about its performance in fire. Current building regulations measure the fire performance of timber using fire resistance tests. In these tests, the charring rate is measured under a series of heat exposures (design fires) and from this the structural performance is deduced. Charring rates are currently only properly understood for the heat exposure of a standard fire, not for other exposures, which restricts the use of performance-based design. This paper studies the charring rates under a range of design fires. We used a multiscale charring model at the microscale (mg-samples), mesoscale (g-samples), and macroscale (kg-samples) for several wood species exposed to different heating regimes and boundary conditions. At the macroscale, the model blindly predicts in-depth temperatures and char depths during standard and parametric fires with an error between 5% and 22%. Comparing simulations of charring under travelling fires, parametric fires, and the standard fire revealed two findings. Firstly, their charring rates significantly differ, with maximum char depths of 42 mm (travelling), 46 mm (parametric), and 59 mm (standard fire), and one (standard fire) to four (travelling fire) charring stages (no charring, slow growth, fast growth, steady-state). Secondly, we observed zero-strength layers (depth between the 200 °C and 300 °C isotherm) of 7 to 12 mm from the exposed surface in travelling fires compared to 5 to 11 mm in parametric fires, and 7 mm in the standard fire. Both traditional design fires and travelling fires, therefore, need to be considered in structural calculations. These results help engineers to move towards performance-based design by allowing the calculation of charring rates for a wide range of design fires. In turn, this will help engineers to build more sustainable and safe structures with timber.

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Section: Discussion On Zero-strength Layermentioning

confidence: 99%

Thermal Response of Timber Slabs Exposed to Travelling Fires and Traditional Design Fires

et al. 2020

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“…However, it must be reiterated that the RCSM method, in its current form, was not developed, and should not be used, for CLT. Previous researchers have already demonstrated that application of the RCSM to CLT is likely to result in unsafe capacity predictions [37][38][39]. It is expected that future versions of the Eurocode will suggest modifications to the charring rates and the zero strength layers to attempt to provide more conservative simplified design solutions for CLT and other engineered timber products.…”

Section: Discussionmentioning

confidence: 99%

Structural Capacity of One-Way Spanning Large-Scale Cross-Laminated Timber Slabs in Standard and Natural Fires

et al. 2020

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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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“…In the early 1990s, CLT was developed in Austria, Germany and Switzerland. The advantages of CLT include shorter building time and a high strength ratio [1]. CLT beams are composed of wood layers, arranged and glued crosswise as illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Composite Laminated Timber (CLT)

Martínez-Martínez

Alonso-Martínez

Rabanal

et al. 2018

The 2nd International Research Conference on Sustainable Energy, Engineering, Materials and Environment

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In the research for sustainable construction, cross-laminated timber (CLT) has gained popularity and become a widely used engineered timber product. However, there are few numerical studies of the structural behaviour of CLT. Among other issues, the orthotropic properties of CLT complicate finite element analysis (FEA). This paper presents a finite element model (FEM) to predict the structural behaviour of CLT beams subjected to sustained flexural loading. This numerical model includes a material model based on the orthotropic material properties of different timber species. Furthermore, the orientation and the properties of each layer are considered. Most of the previous studies simulate CLT beams as a homogeneous material. However, in this work the CLT beam is modelled as a composite material made up of five layers with different orientations and properties. Bonded contacts are used to define the interaction between layers. In addition, nonlinearities, such as large displacement, are used to simulate the behaviour of CLT beams. The model provides the load-displacement relationship and stress concentration. Tsai-Wu failure criteria is used in the simulation to predict the failure modes of the CLT beams studied.

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Structural response of cross-laminated timber compression elements exposed to fire

Cited by 36 publications

References 19 publications

Thermal Response of Timber Slabs Exposed to Travelling Fires and Traditional Design Fires

Thermal Response of Timber Slabs Exposed to Travelling Fires and Traditional Design Fires

Structural Capacity of One-Way Spanning Large-Scale Cross-Laminated Timber Slabs in Standard and Natural Fires

Finite Element Analysis of Composite Laminated Timber (CLT)

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