Bending characteristics of glued laminated timber depending on the alternating effects of freezing and heating

Kytka, Tomáš; Gašparík, Miroslav; Sahula, Lukáš; Karami, Ezatollah; Teterin, Danil; Das, Sumanta; Novák, David; Kvietková, Monika

doi:10.1016/j.conbuildmat.2022.128916

Cited by 6 publications

(6 citation statements)

References 31 publications

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“…Compared to RPF, our results show larger deviations on average, of 5.6% (max. 9%); however, compared to previous research by Kytka et al (2022) [35], in which glulam samples were glued with PUR glue, this average deviation is lower (3.7%).…”

Section: Analytical Modelcontrasting

confidence: 78%

“…The results of the analytical model are presented in Table 3. For a better comparison of the results, the results of the measured values of the modulus of elasticity from previous measurements are also included [35], where the mechanical properties of the same combinations were compared depending on the temperature change. For comparison, only values with the same wood moisture without the influence of temperature changes were selected.…”

Section: Analytical Modelmentioning

confidence: 99%

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Predicted and Experimental Bending Behaviour of Glulam Bonded by RPF Adhesive

Kytka,

Gašparík,

Sahula

et al. 2024

Materials

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In this study, alder, spruce, and beech woods were used for homogeneous symmetric, inhomogeneous symmetric (combined) and inhomogeneous non-symmetric glued laminated timber (glulam) beams glued with resorcinol phenol formaldehyde (RPF) adhesive. The aim of this paper is to determine and compare the modulus of elasticity of glulam beams using three methods, i.e., analytical calculation, numerical model (FEM) and experimental testing. As an additional characteristic, the bending strength (MOR) of the beams was determined during experimental testing. Analytical calculation was used to calculate the modulus of elasticity (MOE) of glued laminated timber based on the knowledge of the modulus of elasticity of solid wood and to estimate the location of the neutral axis during bending. According to calculations, for symmetrical combinations, the deviation from the real neutral axis does not exceed 5%. In the case of the modulus of elasticity, the deviation is an average of 4.1% from that of the actual measured beams. The numerical model includes finite element modelling, where the deflection of the modelled beams can be calculated with a deviation of up to 10%. The last method was experimental testing of glued beams using four-point bending, in which, among homogeneous beams, beech glulam beams achieved the highest MOE and MOR, while alder glulam beams achieved the lowest. The combination of wood species resulted in an increase in both MOE and MOR compared to homogeneous spruce and alder beams.

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Section: Analytical Modelcontrasting

confidence: 78%

Section: Analytical Modelmentioning

confidence: 99%

Predicted and Experimental Bending Behaviour of Glulam Bonded by RPF Adhesive

Kytka,

Gašparík,

Sahula

et al. 2024

Materials

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“…Additionally, considering mechanical load capacities, several other commonly available wood species demonstrate superior mechanical properties compared with spruce. For instance, when combining spruce with beech wood (as in combination K5), our previous research has revealed an approximate 10% increase in both the modulus of elasticity (MOE) and bending strength (MOR) when using PUR adhesive [37]. Furthermore, with RPF adhesive, this combination approached the mechanical properties of a homogeneous beech wood combination, although these specific findings have not been published yet.…”

Section: Resultsmentioning

confidence: 95%

Burning Properties of Combined Glued Laminated Timber

Kytka,

Gašparík,

Novák

et al. 2024

Fire

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This study delved into the combustion properties of combined glulam bonded using polyurethane (PUR) and resorcinol-phenol-formaldehyde (RPF) adhesives. The experiment involved three distinct wood species, namely, spruce, alder, and beech, which were combined in homogeneous, non-homogeneous symmetrical, and non-homogeneous asymmetrical arrangements. These species were selected to represent a spectrum, namely, softwood (spruce), low-density hardwood (alder), and high-density hardwood (beech). The varying combinations of wood species illustrate potential compositions within structural elements, aiming to optimize mechanical bending resistance. Various parameters were measured during combustion, namely, the heat release rate (HRR), peak heat release rate (pHRR), mass loss rate (MLR), average rate of heat emission (ARHE), peak average rate of heat emission (MARHE), time to ignition (TTI), and effective heat of combustion (EHC). The findings indicate that incorporating beech wood into the composite glulam resulted in an increase in heat release, significantly altering the burning characteristics, which was particularly evident at the second peak. Conversely, the use of spruce wood exhibited the lowest heat release rate. Alder wood, when subjected to heat flux at the glued joint, displayed the highest heat emission, aligning with the results for EHC and MARHE. This observation suggests that wood species prone to early thermal decomposition emit more heat within a shorter duration. The time to ignition (TTI) was consistent, occurring between the first and second minute across all tested wood species and combinations. Notably, when subjected to heat flux, the glulam samples bonded with PUR adhesive experienced complete delamination of the initial two glued joints, whereas those bonded with RPF adhesive exhibited only partial delamination.

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“…Oak GLT has shown particularly good mechanical performance under both monotonic and cyclic loading regimes, indicating its potential for use in construction projects. Destructive tests, such as four-point bending tests, push-out shear tests, and cyclic tensile tests, have been undertaken to evaluate the mechanical properties of oak timber for structural applications (Kytka et al 2022).…”

Section: Introductionmentioning

confidence: 99%

11th Hardwood Conference Proceedings

2024

Hardwood Conference Proceedings

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Black locust (Robinia pseudoacacia L.) is the most widespread non-native tree species in Europe and has had a significant impact on the Central European landscape and forestry. The black locust has many exceptional characteristics that represent considerable potential for use by man. The climate shift in recent decades in Central Europe could further strengthen the importance of this tree species. However, there are also risks arising from the invasiveness of the black locust. Like Hungary, Czechia has had many years of experience with this tree species. Still, the current approach between these two countries, particularly in conventional forestry, differs. This paper attempts to summarise how the management of Robinia and its stands is viewed in Czechia, where the common forestry utilization of black locust is currently not considered due to its invasiveness. The reason for a more reserved forestry attitude in Czechia can be associated with the relatively frequent stem deformities of Robinia stands, which are often attributed to frost. However, the frost deformities and low stem-form quality of some Robinia stands do not affect their vigour and potential to invade adjacent habitats. It often takes considerable effort to remove black locust, especially where the spreading of Robinia threatens valuable adjacent ecosystems. On the other hand, there is great potential for the use of Robinia in Czechia. It can be found in controlled energy crops, fast-growing plantations (lignicultures), some land reclamation projects or urban greenery. Robinia can also be grown in small stands or in groups of trees surrounded by arable land that does not allow the tree to spontaneously spread. Regarding the production plantations of Robinia, the Hungarian experience and breeding program can be very inspiring for Czechia. Generally, there is a move towards 'site-specific management', but with a strong emphasis on the precautionary principle. Finding and then consistently applying a balanced approach to black locust management that not only allows for the potential but also respects the risks of Robiniait is currently a key challenge for Czech forestry, landscape and nature conservation.

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Bending characteristics of glued laminated timber depending on the alternating effects of freezing and heating

Cited by 6 publications

References 31 publications

Predicted and Experimental Bending Behaviour of Glulam Bonded by RPF Adhesive

Predicted and Experimental Bending Behaviour of Glulam Bonded by RPF Adhesive

Burning Properties of Combined Glued Laminated Timber

11th Hardwood Conference Proceedings

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