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Hu, M., Olsson, A., Johansson, M., Oscarsson, J. & Serrano, E. (2016). Assessment of a Three-Dimensional Fiber Orientation Model for Timber. Wood and Fiber Science, 48(4), 271-290
Open this publication in new window or tab >>Assessment of a Three-Dimensional Fiber Orientation Model for Timber
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2016 (English)In: Wood and Fiber Science, ISSN 0735-6161, Vol. 48, no 4, p. 271-290Article in journal (Refereed) Published
Abstract [en]

Wood is an orthotropic material with very different properties along and across fibers, and every board has its own pattern of knots and fiber deviations. Therefore, detailed knowledge of the three-dimensional (3D) fiber orientation of individual boards would enable more accurate assessment of properties such as stiffness, strength, and shape stability. This paper presents a method for modeling 3D fiber orientation of side boards of Norway spruce. The method is based on dot laser scanning and utilization of the tracheid effect, and it is verified by a comparison between strain fields calculated on the basis of the fiber orientation model and corresponding strains determined using digital image correlation (DIC) technique. By means of the method, it is possible to identify knots and to reproduce the fiber orientation in clear wood in the vicinity of knots. Fiber orientation models of side boards including traversing edge knots were established and integrated in finite element models of boards used for simulation of four-point bending tests. The same boards were also tested in laboratory and displacement fields of the wide faces were recorded at different load levels using DIC technique. Comparisons of strain fields from measurements and simulations showed close agreement, regarding both strain patterns and strain levels. Local strain concentrations caused by very small defects were detected using the models and also found from the laboratory test results. The modeling approach may be used both to achieve improved accuracy of existing machine strength grading methods and, after further development, also for more advanced analysis of eg crack propagation and strength of timber.

National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-57467 (URN)000388430500006 ()
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2018-01-09Bibliographically approved
Bader, T. K., Schweigler, M., Hochreiner, G., Eberhardsteiner, J., Serrano, E., Dorn, M. & Enquist, B. (2016). Experimental Assessment of the Load Distribution in Multi-Dowel Timber Connections. In: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016: . Paper presented at 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016.
Open this publication in new window or tab >>Experimental Assessment of the Load Distribution in Multi-Dowel Timber Connections
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2016 (English)In: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016, 2016Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

An integrative, hierarchically organized testing procedure for the quantification of the load distribution in multi-dowel timber connections is presented herein. The use of contactless deformation measurement systems allowed the combination of test data from single dowel and multi-dowel connections, which gave access to the loads acting on each dowel over the full loading history. As a consequence of the anisotropic material behavior of wood, a nonuniform and progressively changing load distribution among the dowels was found.

National Category
Building Technologies Wood Science
Research subject
Technology (byts ev till Engineering), Civil engineering; Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-56261 (URN)
Conference
17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016
Available from: 2016-08-31 Created: 2016-08-31 Last updated: 2018-05-17Bibliographically approved
Bader, T. K., Schweigler, M., Hochreiner, G., Enquist, B., Dorn, M. & Serrano, E. (2016). Experimental characterization of the global and local behavior of multi-dowel LVL-connections under complex loading. Materials and Structures, 49(6), 2407-2424
Open this publication in new window or tab >>Experimental characterization of the global and local behavior of multi-dowel LVL-connections under complex loading
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2016 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 6, p. 2407-2424Article in journal (Refereed) Published
Abstract [en]

The thorough experimental characterization of a dowel-type connection under various combinations of bending moments and normal forces is presented in this study. Double-shear steel-to-timber connections with 12 and 20 mm steel dowels were tested in a 4-point bending test set-up. The load, between the connected steel and wood beams, was transferred by the dowels themselves and also via an additional (passive) contact device, which introduced an eccentric normal force in the timber beam. The behavior of the connections was studied at the global scale of the connection and at the local scale of the individual dowels. A non-contact deformation measurement system was used to assess the changes of the location of the center of relative rotation over the entire loading. At the same time, the head deformations of the individual dowels could be measured, giving a direct indication about the force distribution among the dowels. Due to reinforcement, connections behaved distinctly ductile with a global relative rotation of up to 3°. Pre-stressing of the contact device by a force of 40 kN yielded an even stiffer behavior. For the particular configurations tested herein, the center of rotation was found to be close to the vertical axis of symmetry of the joint and close to the top row of the dowels. Moreover, the superimposed vertical shift of the center of relative rotation in case of a delayed normal force could be quantified. © 2015 RILEM

Keywords
Bending moment and normal force, Center of relative rotation, Dowel connection, Ductility, Reinforcement, Timber, Bending moments, Deformation, Rotation, Wooden beams and girders, 4-point bending tests, Center of rotation, Dowel-type connection, Experimental characterization, Force distributions, Normal forces, Relative rotation, Fasteners
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-46196 (URN)10.1617/s11527-015-0657-8 (DOI)000376646900026 ()2-s2.0-84936806518 (Scopus ID)
Available from: 2015-09-10 Created: 2015-09-10 Last updated: 2018-04-25Bibliographically approved
Bader, T. K., Schweigler, M., Hochreiner, G., Serrano, E., Enquist, B. & Dorn, M. (2015). Dowel deformations in multi-dowel LVL-connections under moment loading. Wood Material Science & Engineering, 10(3), 216-231
Open this publication in new window or tab >>Dowel deformations in multi-dowel LVL-connections under moment loading
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2015 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 216-231Article in journal (Refereed) Published
Abstract [en]

The aim of the experimental study presented herein is the assessment and quantification of the behavior of individual dowels in multi-dowel connections loaded by a bending moment. For this purpose, double-shear, steel-to-timber connections with nine steel dowels arranged in different patterns and with different dowel diameters were tested in four-point bending. In order to achieve a ductile behavior with up to 7° relative rotation, the connections were partly reinforced with self-tapping screws. The reinforcement did not influence the global load–deformation behavior, neither for dowel diameters of 12 mm nor for 20 mm, as long as cracking was not decisive. The deformation of the individual dowels was studied by means of a non-contact deformation measurement system. Thus, the crushing deformation, that is, the deformation at the steel plate, and the bending deformation of the dowels could be quantified. In the case of 12 mm dowels, the bending deformation was larger than the crushing deformation, while it was smaller in the case of 20 mm dowels. Moreover, dowels loaded parallel to the grain showed larger bending deformations than dowels loaded perpendicular to the grain. This indicates that the loading of the individual dowels in the connection differs depending on their location.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keywords
bending moment, Dowel connection, ductility, load distribution, reinforcement, timber, Bending moments, Crushing, Deformation, Fasteners, Deformation behavior, Four point bending, Load distributions, Parallel to the grains, Relative rotation, Self-tapping screws, Timber connections, Bending (deformation)
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-46194 (URN)10.1080/17480272.2015.1070372 (DOI)000368739700002 ()2-s2.0-84942191975 (Scopus ID)
Available from: 2015-09-10 Created: 2015-09-10 Last updated: 2018-04-25Bibliographically approved
Kozłowski, M., Dorn, M. & Serrano, E. (2015). Experimental testing of load-bearing timber–glass composite shear walls and beams. Wood Material Science & Engineering, 10(3), 276-286
Open this publication in new window or tab >>Experimental testing of load-bearing timber–glass composite shear walls and beams
2015 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, p. 276-286Article in journal (Refereed) Published
Abstract [en]

The paper presents results from the experimental testing of load-bearing timber–glass composite shear walls and beams. Shear wall specimens measuring 1200 × 2400 mm2 manufactured with three adhesives of varying stiffness were tested. Twelve specimens with a single 10 mm thick glass pane and one specimen with an additional insulating glass unit were produced. The testing procedures involved various loading conditions: pure vertical load and different combinations of shear and vertical loading. The test results showed that the adhesive had only a minor influence on the buckling load which was the main failure mechanism. 240 mm high and 4800 mm long timber–glass beams manufactured with adhesives of different stiffness were tested. For the webs, two types of glass were used: annealed float and heat-strengthened glass, in both cases 8 mm thick panes were used. In total, 12 beams were tested in four-point bending until failure. Despite the considerable difference in adhesive stiffness, beam bending stiffness was similar. Concerning load-bearing capacity, the beams with heat-strengthened glass were approximately 50% stronger than the beams made using annealed float glass.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keywords
beam; finite-element analysis; shear wall; Structural glass; timber–glass composites
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-46190 (URN)10.1080/17480272.2015.1061595 (DOI)000368739700006 ()2-s2.0-84942193967 (Scopus ID)
Funder
VINNOVA
Available from: 2015-09-10 Created: 2015-09-10 Last updated: 2018-04-18Bibliographically approved
Bader, T. K., Schweigler, M., Hochreiner, G., Eberhardsteiner, J., Dorn, M. & Serrano, E. (2015). Integrative Research for an Enhanced Design of Dowel Connections. In: Proceedings of the EUROMECH Colloquium 556 on Theoretical, Numerical, and Experimental Analyses in Wood Mechanics: . Paper presented at EUROMECH Colloquium 556: Theoretical, Numerical, and Experimental Analyses in Wood Mechanics, 27 May – 29 May 2015, Dresden, Germany.
Open this publication in new window or tab >>Integrative Research for an Enhanced Design of Dowel Connections
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2015 (English)In: Proceedings of the EUROMECH Colloquium 556 on Theoretical, Numerical, and Experimental Analyses in Wood Mechanics, 2015Conference paper, Oral presentation with published abstract (Refereed)
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-44209 (URN)978-3-00-049643-1 (ISBN)
Conference
EUROMECH Colloquium 556: Theoretical, Numerical, and Experimental Analyses in Wood Mechanics, 27 May – 29 May 2015, Dresden, Germany
Available from: 2015-06-14 Created: 2015-06-14 Last updated: 2016-04-05Bibliographically approved
Dorn, M., Kozłowski, M. & Serrano, E. (2014). Design approaches for timber-glass beams. In: Schneider, Jens and Weller, Bernhard (Ed.), Glass, facade, energy : Engineered Transparency International Conference at glasstec: Conference on Glass, Glass Technology, Facade Engineering and Solar Energy, 21 and 22 October 2014. Paper presented at Conference on Glass, Glass Technology, Facade Engineering and Solar Energy, 21 and 22 October 2014.
Open this publication in new window or tab >>Design approaches for timber-glass beams
2014 (English)In: Glass, facade, energy : Engineered Transparency International Conference at glasstec: Conference on Glass, Glass Technology, Facade Engineering and Solar Energy, 21 and 22 October 2014 / [ed] Schneider, Jens and Weller, Bernhard, 2014Conference paper, Published paper (Refereed)
Abstract [en]

This paper relates to the mechanical performance of timber-glass composite beams, which take exceptional advantage of the combination of the materials involved. Beam bending tests were performed with beams made from float glass and heat-strengthened glass. Three different adhesive types were used: silicone, acrylate and epoxy. The test results show that, with a proper design, the timber is able to transfer load after glass failure and hence collapse is delayed and a ductile behavior can be obtained. The results from the tests were compared with an analytical method using the gamma-method and the agreement between the analytical method and the tests are shown to be excellent.

Keywords
timber-glass composite beams, design approach, numerical simulation, experiments, gamma-method
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-38161 (URN)978-3-86780-402-8 (ISBN)
Conference
Conference on Glass, Glass Technology, Facade Engineering and Solar Energy, 21 and 22 October 2014
Available from: 2014-11-13 Created: 2014-11-13 Last updated: 2015-09-28Bibliographically approved
Dorn, M., Kozłowski, M., Serrano, E. & Enquist, B. (2014). Development of large-scale load-bearing timber-glass structural elements. In: WCTE 2014 - World Conference on Timber Engineering: Proceedings. Paper presented at WCTE 2014, World Conference on Timber Engineering, Quebec City, Canada, August 10-14, 2014.
Open this publication in new window or tab >>Development of large-scale load-bearing timber-glass structural elements
2014 (English)In: WCTE 2014 - World Conference on Timber Engineering: Proceedings, 2014Conference paper, Published paper (Refereed)
Abstract [en]

The building industry demands ever more effective structural elements with a multitude of requirements at the same time. There is increasing interest for load-bearing glass elements which can be deployed in timber structures, e.g. in the outer façade or as column or beam elements within the building. In an on-going research project, the materials glass, timber and the adhesive combining the former have to be selected to fit each other but also suit the application. The mechanical properties are studied individually as well as in combined small-scale specimens experimentally. Furthermore,large-scale tests on beams and shear walls are performed. This is accompanied by numerical analysis to study a wide range of dimensions and variations as well as specific design situations. The final output of the project will be prototypes to beused in showcase projects.

Keywords
timber-glass composites, integrated structures, shear wa
National Category
Construction Management
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-37275 (URN)2-s2.0-84924944175 (Scopus ID)
Conference
WCTE 2014, World Conference on Timber Engineering, Quebec City, Canada, August 10-14, 2014
Projects
LBTGC - Load bearing timber glass composites
Funder
VINNOVA, 2011-02266
Available from: 2014-09-25 Created: 2014-09-25 Last updated: 2016-12-07Bibliographically approved
Kozłowski, M., Serrano, E. & Enquist, B. (2014). Experimental investigation on timber-glass composite I-beams. In: Louter, Bos, Belis and Lebet (Ed.), Challenging Glass 4- Structural Glass-Novel design methods and next generation products: . Paper presented at Challenging Glass 4 & COST Action TU0905 Final Conference, 6-7 February 2014, Lausanne, Switzerland,. Taylor & Francis
Open this publication in new window or tab >>Experimental investigation on timber-glass composite I-beams
2014 (English)In: Challenging Glass 4- Structural Glass-Novel design methods and next generation products / [ed] Louter, Bos, Belis and Lebet, Taylor & Francis, 2014Conference paper, Published paper (Refereed)
Abstract [en]

Timber-glass composite I-beams were manufactured and tested in bending to failure. The glass web of the I-beam was adhesively bonded to the timber flanges using three different adhesives: Epoxy, Acrylate and Silicone. For the webs two types of 8 mm thick glass were used: annealed float and heat heat-strengthened glass. Before testing the beams with heat-strengthened glass, the residual-stress profile through the thickness of the glass panels was measured using a portable scattered light polariscope SCALP. The results show that the beam stiffness was similar for the acrylate and epoxy-bonded beams, despite the difference in adhesive stiffness. The beams bonded with the silicone adhesive showed approximately 25% lower stiffness. In terms of load bearing capacity, the beams made using heat-strengthened glass were approximately 50% stronger than the beams made using annealed float, for the epoxy and acrylate adhesive. Using the silicone adhesive, the increase was approximately 20%.

Place, publisher, year, edition, pages
Taylor & Francis, 2014
National Category
Engineering and Technology Construction Management
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-37277 (URN)2-s2.0-84893960507 (Scopus ID)978-1-138-00164-0 (ISBN)
Conference
Challenging Glass 4 & COST Action TU0905 Final Conference, 6-7 February 2014, Lausanne, Switzerland,
Projects
LBTGC - Load bearing imber glass composites
Funder
Vinnova, 2011-02266
Available from: 2014-09-25 Created: 2014-09-25 Last updated: 2019-08-27Bibliographically approved
Sterley, M., Serrano, E., Enquist, B. & Hornatowska, J. (2014). Finger jointing of freshly sawn Norway Spruce side boards: a comparative study of fracture properties of joints glued with phenol-resorcinol and one-component polyurethane adhesive. In: Materials and Joints in Timber Structures: Recent Developments of Technology. Paper presented at RILEM International Symposium on Materials and Joints in Timber Structures, Stuttgart, GERMANY, OCT 08-10, 2013 (pp. 325-339). Springer
Open this publication in new window or tab >>Finger jointing of freshly sawn Norway Spruce side boards: a comparative study of fracture properties of joints glued with phenol-resorcinol and one-component polyurethane adhesive
2014 (English)In: Materials and Joints in Timber Structures: Recent Developments of Technology, Springer, 2014, p. 325-339Conference paper, Published paper (Other academic)
Abstract [en]

Finger jointing of unseasoned Norway Spruce was studied with respect to tensile strength, adhesive penetration and durability. Finger joints were manufactured with 1) unseasoned wood and one component polyurethane (PUR) adhesive, 2) dried wood and PUR adhesive and 3) dried wood and phenol resorcinol formaldehyde (PRF) adhesive. Two levels of wood density were used. The tensile strength of the finger joints was determined and the deformations within the joint were studied with an optical measurement system (ARAMIS). The penetration of the adhesive was studied with x-ray microtomography. The durability of the joints was determined according to the standard ASTM D 4688. The results show that the tensile strength and the durability of green glued finger joints are on the same level as that of dry glued PUR joints. The penetration of the PUR adhesive is high in the unseasoned wood and cavities within the bonds seem to be smaller than in dry glued PUR joints. The tensile strength of the finger joints is dependent on density, independent on the adhesive system used. The strength of the green glued PUR adhesive bonds in finger joints measured with small scale specimens did not differ from the strength of the dry glued PUR bonds.

Place, publisher, year, edition, pages
Springer, 2014
Series
RILEM Bookseries, ISSN 2211-0844 ; 9
Keywords
finger joint, bond line, fracture, green gluing, digital image correlation, x-ray tomography
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-18603 (URN)10.1007/978-94-007-7811-5_30 (DOI)000329970600030 ()2-s2.0-84885449084 (Scopus ID)978-94-007-7810-8 (ISBN)
Conference
RILEM International Symposium on Materials and Joints in Timber Structures, Stuttgart, GERMANY, OCT 08-10, 2013
Available from: 2012-05-08 Created: 2012-05-08 Last updated: 2018-02-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5333-0682

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