Influence of ply configuration and adhesive type on cross-laminated timber in flexure at elevated temperatures

Wiesner, Felix; Deeny, Susan; Bisby, Luke

doi:10.1016/j.firesaf.2020.103073

Cited by 12 publications

(3 citation statements)

References 9 publications

(10 reference statements)

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“…Internal moments could be caused by non-uniform heating, as is the case for the transiently heated samples, however, this does not explain why there is also a difference for the steady state samples heated to approximately 50 °C. The effect of accelerated loss of composite action for PU compared to MF bonded specimen has also been reported for samples in four point bending of the same CLT stock as the samples herein by parallel studies [39]. Another possible explanation, independent of the occurrence of bending or buckling in the specimens, could be the loss or weakening of the lamination effect, which is shown to significantly improve the strength for five plies at ambient temperature.…”

Section: Elevated Temperaturessupporting

confidence: 74%

The effect of adhesive type and ply number on the compressive strength retention of CLT at elevated temperatures

Wiesner

Thomson

Bisby

2021

Construction and Building Materials

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This paper describes novel experiments to identify the reduction in compressive strength of crosslaminated timber (CLT) at elevated temperatures. The adhesive type and number of timber plies was varied between CLT samples to allow an assessment of the CLT 'system', rather than timber only. Samples were subjected to steady state and transient heating conditions and their ultimate load bearing capacities were measured. At ambient reference temperatures, a statistically significant difference in ultimate compressive strength was observed between ply numbers but not between adhesive types. For transiently heated samples, capacity was reduced at 100 °C for CLT bonded with polyurethane adhesive type as compared to samples bonded with melamine formaldehyde. The presented results indicate that the composition of CLT can influence the whole system structural response, both at ambient temperature and under fire conditions.

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Section: Elevated Temperaturessupporting

confidence: 74%

The effect of adhesive type and ply number on the compressive strength retention of CLT at elevated temperatures

Wiesner

Thomson

Bisby

2021

Construction and Building Materials

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“…Finally, future research could consider the effect of combined heating and loading of cracked timber. Previous research has shown that creep can occur in timber that is simultaneously heated and loaded 43 and the expected crack width could be impacted by this effect.…”

Section: Methodsmentioning

confidence: 99%

“…Previous research has shown that creep can occur in timber that is simultaneously heated and loaded 43 and the expected crack width could be impacted by this effect.…”

Section: Limitationsmentioning

confidence: 99%

The effects of radial cracks on the fire performance of heritage timber

et al. 2022

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Heritage timber buildings are found worldwide and their irreplaceable nature makes them of high value. A common occurrence on heritage timber members is radial shrinkage cracks resulting from changing moisture contents over time. There is little information available that can be used to assess the fire performance of heritage timber members (which has unique differences from contemporary timber), and to the author's awareness, no information regarding how the presence of radial cracks affects the fire performance and char depth of a timber member. The purpose of this study is to provide an evaluation of the effects of radial cracking on the fire performance of timber members, including its effect on char depth, time to ignition, and residual strength. Full-scale heritage Pine timber members were procured from a 115-year-old building undergoing demolition and then subjected to a pool fire.Cracked samples were also extracted from the members and tested in a Cone Calorimeter apparatus relative to solid samples. It was found that the presence of cracks did allow for deeper charring with the full-scale tests showing 64% greater char depth in the cracked region and the Cone Calorimeter tests showing 29% greater char depth on the cracked samples. Four-point bending tests of the full-scale members subjected to a pool fire showed that the effect of the fire exposure and the cracks did not significantly impact the capacity of the members (7.2% difference) but reduced the stiffness as the ultimate deflection increased by 43%. These results can help to inform practitioners who encounter heritage timber members to more accurately assess the fire performance of the member, such that they can make informed decisions on the level of fire protection required. The study also provides methodologies for the collection of heritage timber test materials.

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Scale modeling of thermo-structural fire tests of multi-orientation wood laminates

Gangi,

Lattimer,

Case

2024

Wood Sci Technol

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The stacking sequence of laminated wood significantly impacts the composite mechanical behavior of the material, especially when scaling down thermo-mechanical tests on plywood. In previous research, we developed a scaling methodology for thermo-structural tests on samples with similar cross sections, however this paper focused on testing plywood samples with different stacking sequences between the scales. Plywood samples at ½-scale and ¼-scale were subjected to combined bending and thermal loading, with the loading scaled to have the same initial static bending stresses. While the ¼-scale 4-layer [0°/90°]s laminate and the ½-scale 8-layer [0°/90°/90°/0°]s laminate had an equal number of 0° and 90° layers, as the char front progresses, the sections behave differently. Thus, modeling becomes essential to extrapolating the data from the smaller ¼-scale test to predict the behavior of the larger ½-scale test. Reduced cross-sectional area models (RCAM) incorporating classical laminated plate theory were used to predict the mechanical response of the composite samples as the char front increased. Three methods were proposed for calibrating the RCAM models: Fourier number scaling, from detailed kinetics-based pyrolysis GPyro models, and fitting to data from fire exposure thermal response tests. The models calibrated with the experimental char measurements produced the most accurate predictions. The experimental char models validated to predict the behavior of the ¼-scale tests within 2.5%, were then able to predict the ½-scale test behavior within 4.5%.

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Influence of ply configuration and adhesive type on cross-laminated timber in flexure at elevated temperatures

Abstract: CLT beams were subjected to heating under sustained loading.• Significant effect of adhesive type on heat induced deflections was measured.• Sizeable heat induced deflections were found to be irrecoverable.

Cited by 12 publications

References 9 publications

The effect of adhesive type and ply number on the compressive strength retention of CLT at elevated temperatures

The effect of adhesive type and ply number on the compressive strength retention of CLT at elevated temperatures

The effects of radial cracks on the fire performance of heritage timber

Scale modeling of thermo-structural fire tests of multi-orientation wood laminates

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