| 1. |
- Nziengui, Claude Feldman Pambou, et al.
(författare)
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Experimental assessment of the annual growth ring’s impact on the mechanical behavior of temperate and tropical species
- 2020
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Ingår i: BioResources. - : NC State University. - 1930-2126. ; 15:2, s. 4282-4293
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Tidskriftsartikel (refereegranskat)abstract
- An innovative experimental protocol is presented, linking a nondestructive (on computed tomography scanner) and destructive approach (bending test on electrostatic press). This study aimed to evaluate the annual growth ring’s impact on the mechanical behavior of wood. The tests were carried out on temperate specimens (Pseudotsuga menziesii and Abies alba Mill) from the Massif Central Region of France and tropical specimens (Aucoumea klaineana Pierre, Milicia excelsa, and Pterocarpus soyauxii) from Gabon. The connection between the mechanical parameters, taken from these tests and their structural characteristics, are also highlighted. Based on these results, a database was formed of the annual growth ring’s impact on the mechanical characteristics of these species. A link was found between the annual growth ring and the mechanical and physical characteristics of the species. The number and width of the earlywood ring and its mechanical properties were also investigated for each type of species. This comparison and the link highlighted was possible due to the study of the impact of dry density’s specimens, considered in this work as an adjustment parameter on the study of the mechanical behavior of these species.
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| 2. |
- Turesson, Jonas, 1991-, et al.
(författare)
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Influence of laminate direction and glue area on in-plane shear modulus of cross-laminated timber
- 2020
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Ingår i: SN Applied Sciences. - : Springer. - 2523-3963 .- 2523-3971. ; 2:12
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Tidskriftsartikel (refereegranskat)abstract
- The use of cross-laminated timber (CLT) in constructing tall buildings has increased. So, it has become crucial to get a higher in-plane stiffness in CLT panels. One way of increasing the shear modulus, G, for CLT panels can be by alternating the layers to other angles than the traditional 0° and 90°. The diagonal compression test can be used to measure the shear stiffness from which G is calculated. A general equation for calculating the G value for the CLT panels tested in the diagonal compression test was established and verified by tests, finite element simulations and external data. The equation was created from finite element simulations of full-scale CLT walls. By this equation, the influence on the G value was a factor of 2.8 and 2.0 by alternating the main laminate direction of the mid layer from the traditional 90° to 45° and 30°, respectively. From practical tests, these increases were measured to 2.9 and 1.8, respectively. Another influence on the G value was studied by the reduction of the glue area between the layers. It was shown that the pattern of the contact area was more important than the size of the contact area.
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| 3. |
- Turesson, Jonas, 1991-, et al.
(författare)
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Shear modulus analysis of cross-laminated timber using picture frame tests and finite element simulations
- 2020
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Ingår i: Materials and Structures. - : Springer Nature. - 1359-5997 .- 1871-6873. ; 53:4
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Tidskriftsartikel (refereegranskat)abstract
- Determining the mechanical properties of cross-laminated timber (CLT) panels is an important issue. A property that is particularly important for CLT used as shear walls in buildings is the in-plane shear modulus. In this study, a method to determine the in-plane shear modulus of 3- and 5-layer CLT panels was developed based on picture frame tests and a correction factor evaluated from finite element simulations. The picture frame test is a biaxial test where a panel is simultaneously compressed and tensioned. Two different testing methods are simulated by finite elements: theoretical pure shear models as a reference cases and picture frame models to simulate the picture frame test setup. An equation for calculating the shear modulus from the measured shear stiffnesses in the picture frame tests is developed by comparisons between tests and finite element simulations of the CLT panels. The results show that pure shear conditions are achieved in the central region of the panels. No influence from the size of the tested panels is observed in the finite element simulations.
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