lnu.sePublications
Change search
Refine search result
12 1 - 50 of 53
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Bader, Thomas K.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. TU Wien, Austria.
    Schweigler, M.
    TU Wien, Austria.
    Hochreiner, Georg
    TU Wien, Austria.
    Eberhardsteiner, Josef
    TU Wien, Austria.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Integrative Research for an Enhanced Design of Dowel Connections2015In: Proceedings of the EUROMECH Colloquium 556 on Theoretical, Numerical, and Experimental Analyses in Wood Mechanics, 2015Conference paper (Refereed)
  • 2.
    Bader, Thomas K.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Hochreiner, Georg
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Serrano, Erik
    Lund University.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Experimental Assessment of the Load Distribution in Multi-Dowel Timber Connections2016In: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016, 2016Conference paper (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.

  • 3.
    Bader, Thomas K.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria .
    Hochreiner, Georg
    Vienna University of Technology, Austria .
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University.
    Experimental characterization of the global and local behavior of multi-dowel LVL-connections under complex loading2016In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 6, 2407-2424 p.Article in journal (Refereed)
    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

  • 4.
    Bader, Thomas K.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Vienna University of Technology, Austria.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Hochreiner, Georg
    Vienna University of Technology, Austria.
    Serrano, Erik
    Lund University, Sweden.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dowel deformations in multi-dowel LVL-connections under moment loading2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, 216-231 p.Article in journal (Refereed)
    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.

  • 5.
    Bengtsson, Charlotte
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Fonselius, Mikael
    Riipola, Kirsti
    Conformity assessment for machine graded timber by using output control2008Report (Other academic)
    Abstract [en]

    In the Nordic countries machine strength grading of structural timber is becoming increasingly important. A new standard, EN 14081, which allows CE-marking of strength graded structural timber was recently accepted. This standard allows both machine

    control and output control as methods for controlling the graded timber. Machine control is most commonly used in Europe. The project reported here deals with output control. This method is commonly used in for example USA.

    Theoretical studies carried out within this project show that applying output control gives higher yield, especially in high strength classes. A document describing the implementation of the output control procedure is written and given in Appendix 1 of this report.

  • 6. Blumer, Samuel
    et al.
    Niemz, Peter
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Gustafsson, Per Johan
    Moisture induced stresses and deformations in parquet floors: An experimental and numerical study2009In: Wood research, ISSN 1336-4561, Vol. 54, no 1, 89-101 p.Article in journal (Refereed)
    Abstract [en]

    The indoor climate in buildings has changed in the last decade due to more efficient climatic systems, floor heating systems and larger open floor areas with more natural light. All this has induced increasing ranges of relative humidity between different seasons. Also with decreasing relative humidity (in the winter 30-50% RH, in the summer 70-90% RH), floor-heating systems increase the temperature in wooden parquet planks for example. Such variations can result in troublesome deformations, delamination of the surface layer and development of cracks in the parquet flooring boards. Sometimes there is only deterioration of the appearance but the durability of the flooring system can also be reduced. Many laboratory tests have to be done before reaching an optimal design of the parquet elements. Due to high coasts and time constraints of experiments, other supplementary research methods should be tested and evaluated. The articles' main objective was to increase understanding of the behaviour of parquet floors exposed to different climatic conditions using numerical calculation. The use of the finite element models provides options for design purposes of wood flooring systems. Several finite element models for adequate design have been created, tested and applied. After calibration and validation of the calculation method, parameter studies on the influence of material properties, geometry of the parquet floors and the long-term behaviour of the wood and glue line were performed. The results show a strong relation between material and geometry choice on the deformation, for example the gap opening and on the stress distribution in glue line, which can induce delamination of the surface layer and distortional effects of the parquet boards

  • 7.
    Blyberg, Louise
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Lang, Maria
    Glafo, SE-35196 Växjö, Sweden.
    Lundstedt, Karin
    Glafo, SE-35196 Växjö, Sweden.
    Schander, Matilda
    Glafo, SE-35196 Växjö, Sweden.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Silfverhielm, Magnus
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Stålhandske, Christina
    Glafo, SE-35196 Växjö, Sweden.
    Glass, timber and adhesive joints - Innovative load bearing building components2014In: Construction and Building Materials, ISSN 0950-0618, Vol. 55, 470-478 p.Article in journal (Refereed)
    Abstract [en]

    Structural glass-timber composite beams and shear wall elements were investigated in terms of their mechanical behaviour, energy performance and their LCA performance. The load bearing components were manufactured using annealed float glass which was adhesively bonded to the timber with different adhesives. The results show, among other things, that is is possible to join the two materials glass and timber and obtaining a non-brittle failure of the beams. The shear wall elements have the potential of being used as stabilising elements and load bearing walls in buildings of up to 4 storeys height. It is possible to combine glass and timber in a load bearing shear wall without loss of energy performance of a building or without loosing LCA performance. In addition to these benefits, the timber glass composite wall has, of course the benefit of being transparent.

  • 8.
    Blyberg, Louise
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Timber/Glass adhesively bonded I-beams2011In: Glass Performance Days, Conference Proceedings, 2011, 2011, 451-456 p.Conference paper (Other academic)
    Abstract [en]

    Timber and glass are materials with aesthetically pleasing properties. If the materials can be combined appropriately, drawbacks can be overcome and the beneficial mechanical properties utilised and timber/glass elements can be a natural part of the load-carrying structure of buildings. Since glass is a brittle material, an important task for the timber is to provide redundancy – a glass failure should not lead to a catastrophic failure of the entire structural element.

    This paper presents results from ongoing research related to load-bearing components made of timber and glass. Results from tests on small timber/glass bond-line specimens, recently submitted for publication, are briefly presented. The core of the paper is, however, a study of fourpoint bending tests on twelve timber/glass I-beams with acrylate adhesive. These I-beams had a nominal height of 240 mm and were designed with a web of 10 mm float glass and flanges of LVL (laminated veneer lumber), bonded together with an acrylate adhesive.

    The mean values of the beams imply that the ultimate load capacity is 240 % of the load when the fi rst crack in the glass appeared. Thus, the timber well fulfils the redundancy task of avoiding a catastrophic failure of the structural element.

  • 9.
    Blyberg, Louise
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sterley, Magdalena
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Adhesive joints for structural timber/glass applications: Experimental testing and evaluation methods2012In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 35, 76-87 p.Article in journal (Refereed)
    Abstract [en]

    A study of three different adhesives, silicone, acrylate and polyurethane, intended for adhesive joints in structural timber/glass applications is presented in this paper. Intentionally, adhesives with a wide range of properties were chosen. The adhesive bonds between timber and glass were tested both in tension and in shear with a bond area of 800 mm2. Special fixtures were designed both for gluing and testing the specimens. The results include strength and failure type of the adhesive bond as well as deformation of the bond lines, measured with LVDTs and a non-contact optical 3D-deformation measuring system used in combination with finite element modelling in order to obtain detailed information about the behaviour.

    Of the tested adhesives, the acrylate (SikaFast 5215) provided the largest strength, both in tension and shear. The mean strength obtained for this adhesive bond was 3.0 MPa in tension and 4.5 MPa in shear.

    Further, it is demonstrated how rotations in the specimen during the test can be detected with the optical measuring system and how finite element modelling can be used to study the stress distribution internally in the adhesive bond. One conclusion obtained from the combination of results from the optical measuring system and finite element modelling is that the behaviour of the silicone adhesive is highly influenced by its near incompressible behaviour.

  • 10.
    Blyberg, Louise
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sterley, Magdalena
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Timber/Glass Adhesive Bonds: Experimental testing and evaluation methods2010Report (Other academic)
    Abstract [en]

    Both timber and glass are materials that have aesthetically pleasing properties. An appealing idea is to combine them to overcome the drawbacks and utilise the beneficial mechanical properties. Adhesive bonding with an appropriate adhesive could provide a uniform stress distribution at the transition between the materials.

    This report presents a study of three different adhesives, silicone, acrylate and polyurethane. Intentionally, adhesives with a wide range of properties were chosen. The adhesive bonds between timber and glass were tested both in tension and in shear with rather small bonds, 800 mm2. Special fixtures were designed both for gluing and testing of the adhesive bond specimens studied. The results presented include a traditional study of strength, failure type and relative displacement measured with LVDT’s, but also an extended study with a non-contact optical 3D-deformation measuring system and finite element modelling.

    Of the adhesives tested, the acrylate (SikaFast 5215) performed best, both in tension and shear. The mean strength obtained for this adhesive was 3.0 MPa in tension and 4.5 MPa in shear. Even if an important factor when gluing glass is the load distribution ability, the flexible silicone adhesive has too low stiffness and strength for use in structural components, where structural refers to the ability of a component to carry loads other than its own weight.

  • 11.
    Dorn, Michael
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Kozłowski, Marcin
    Silesian University of Technology, Poland.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Design approaches for timber-glass beams2014In: 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 (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.

  • 12.
    Dorn, Michael
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Kozłowski, Marcin
    Silesian University of Technology, Poland.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Development of large-scale load-bearing timber-glass structural elements2014In: WCTE 2014 - World Conference on Timber Engineering: Proceedings, 2014Conference 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.

  • 13. Eriksson, Jerry
    et al.
    Ludvigsson, Mikael
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Load bearing timber glass composites: A WoodWisdom-Netproject for innovative building system2013In: COST Action TU0905 Mid-term Conference on Structural Glass / [ed] Jan Belis; Christian Louter; Danijel Mocibob, Boca Raton, Fla: CRC Press, 2013Conference paper (Refereed)
    Abstract [en]

    The aim of this three year project, which is part of the WoodWisdom-Net researchprogram, is to develop an innovative load bearing building system composed of timberglasscomposites. The structural loads applied onto these composites will be transferred to, andsupported by, the glass component, in contrary to today’s traditional solutions where glass elementsonly function as an environmental shield. Using such structural elements will make itpossible to largely increase the glass surface in buildings, allowing the presence of more naturallight in personal homes and office buildings.

    Timber-glass shear walls and beams will be developed taking into consideration long-term behaviorand seismic performance. Design concepts, feasibility studies and performance assessmentsof these components will be performed in order to improve the overall performance. Theproject also includes the development of new design calculations as well as the optimization ofmanufacturing methods.

    Material properties of timber, glass and adhesives will be determined from small and large scaleexperimental investigations, and will be used as input for theoretical calculations and modelingwork. The projects industrial partners will function as expertise and take part in the developmentand construction of demonstration objects.

    The project consortium is composed of academic and industrial partners from Austria, Sweden,Germany, Turkey, Slovenia, Chile, and Brazil. This paper presents material specifications andresults from small scale testing performed by the Swedish project partners.

  • 14.
    Hochreiner, G.
    et al.
    Vienna University of Technology, Austria.
    Füssl, J.
    Vienna University of Technology, Austria.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Eberhardsteiner, J.
    Vienna University of Technology, Austria.
    Influence of Wooden Board Strength Class on the Performance of Cross-laminated Timber Plates Investigated by Means of Full-field Deformation Measurements2014In: Strain, ISSN 0039-2103, E-ISSN 1475-1305, Vol. 50, no 2, 161-173 p.Article in journal (Refereed)
    Abstract [en]

    Although cross-laminated timber (CLT) plates are increasingly used in high-performance building structures, a tailored composition of them or, at least, a performance-based classification scheme is not available. Especially, the influence of the quality of the ‘raw’ material (wooden boards) on the load carrying capacity of CLT elements is hardly investigated yet. For this reason, within this work, bending tests on 24 CLT plates consisting of wooden boards from three different strength classes have been carried out. The global mechanical response as well as the formation of failure mechanisms were investigated, including a full-field deformation measurement system, which allowed for a qualitatively as well as quantitatively identification of board failure modes. Interestingly, no influence of the board strength class on the elastic limit load of the CLT plates was observed, but the situation was different for the load displacement history beyond the elastic regime, where basically, two different global failure mechanisms could be distinguished. The obtained knowledge about the ‘post-elastic’ behaviour of CLT plates may serve as a basis for the optimisation of CLT products and the development or improvement of design concepts, respectively. Moreover, the obtained large ‘post-elastic’ capacity reserve of CLT consisting of high quality boards could lead to a better utilisation of the raw material.

  • 15.
    Hu, Min
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Johansson, Marie
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University.
    Assessment of a Three-Dimensional Fiber Orientation Model for Timber2016In: Wood and Fiber Science, ISSN 0735-6161, Vol. 48, no 4, 271-290 p.Article in journal (Refereed)
    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.

  • 16.
    Kozłowski, Marcin
    et al.
    Silesian University of Technology, Poland.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Experimental testing of load-bearing timber–glass composite shear walls and beams2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 3, 276-286 p.Article in journal (Refereed)
    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.

  • 17.
    Kozłowski, Marcin
    et al.
    Silesian University of Technology, Poland.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology. Lund University.
    Experimental investigation on timber-glass composite I-beams2014In: Challenging Glass 4- Structural Glass-Novel design methods and next generation products / [ed] Louter, Bos, Belis and Lebet, Taylor & Francis Group, 2014Conference 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%.

  • 18.
    Nicklisch, Felix
    et al.
    Technische Universität Dresden, Germany.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Weller, Bernhard
    Technische Universität Dresden, Germany.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Joint study on material properties of adhesives to be used in load-bearing timber-glass composite elements2014In: Glass | Facade | Energy / [ed] Jens Schneider, Bernhard Weller, Technische Uni Dresden , 2014, 271-280 p.Conference paper (Refereed)
    Abstract [en]

    Beyond its transparency, glass offers a large potential to fulfill load-bearing functions. Timber-glass composite elements take advantage of the high stiffness and strength of glass. At the same time the post-breakage behavior of the composite element increases significantly compared to the brittle failure of a pure glass. The current study relates to timber-glass composites where the composite action is obtained via a linear bondline connecting the glass pane to a timber frame. The full potential of these composite elements arises from the use of adhesives of medium and high stiffness which exhibit rather small deformations compared to e.g. structural silicones. A central objective of the research is the assessment and the optimization of the bondline properties with respect to stiffness of the adhesive. The paper summarizes the results of an in-depth study on commercially available adhesives and evaluates their general suitability in timber-glass composites.

    The material properties of the adhesives were determined by thorough mechanical testing of the bulk material in the first place under varying conditions, typically encountered in façades. The potential use in glass-timber composites was then evaluated using small bonded specimens comprising birch plywood or massive pine wood in combination with soda-lime glass. Failure modes were categorized in order to ascertain the influence of the timber strength on the load-bearing capacity.

    In order to guarantee reliable results from various sources, parts of the tests were executed repeatedly at different laboratories. Results were compared and validated throughout the project. Hence the results of this study provide a reliable basis for material models used in e.g. numerical analysis and engineered design solutions. The study presented here is part of the WoodWisdomNet project “LBTGC - Load Bearing Timber Glass Composites”

  • 19.
    Olsson, Anders
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology. SP Technical Research Institute of Sweden.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Johansson, Marie
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Prediction of timber bending strength and in-member cross-sectional stiffness vartiation on basis of local wood fibre orientation2013In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 71, no 3, 319-333 p.Article in journal (Refereed)
    Abstract [en]

    Machine strength grading of structural timber is based upon relationships between so called indicating properties (IPs) and bending strength. However, such relationships applied on the market today are rather poor. In this paper, new IPs and a new grading method resulting in more precise strength predictions are presented. The local fibre orientation on face and edge surfaces of wooden boards was identified using high resolution laser scanning. In combination with knowledge regarding basic wood material properties for each investigated board, the grain angle information enabled a calculation of the variation of the local MOE in the longitudinal direction of the boards. By integration over cross-sections along the board, an edgewise bending stiffness profile and a longitudinal stiffness profile, respectively, were calculated. A new IP was defined as the lowest bending stiffness determined along the board. For a sample of 105 boards of Norway spruce of dimension 45 × 145 × 3600 mm, a coefficient of determination as high as 0.68-0.71 was achieved between this new IP and bending strength. For the same sample, the coefficient of determination between global MOE, based on the first longitudinal resonance frequency and the board density, and strength was only 0.59. Furthermore, it is shown that improved accuracy when determining the stiffness profiles of boards will lead to even better predictions of bending strength. The results thus motivate both an industrial implementation of the suggested method and further research aiming at more accurately determined board stiffness profiles.

  • 20.
    Olsson, Anders
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Johansson, Marie
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Förfarande och anordning för utvärdering av en bräda av trä2014Patent (Other (popular science, discussion, etc.))
    Abstract [sv]

    Föreliggande redogörelse avser en metod och en anordning för utvärdering av en bräda av trä med en ländriktning. Data som indikerar fiberorienteringen över brädans yta inhämtas och för ett antal underpartier hos brädan bestäms en nominell, lokal elasticitetsmodul, MOE, på basis av nämnda fiberorienteringsdata och en nominell materialparameter. En nominell global MOE i längdriktningen för träbrädan i sin helhet genereras och jämförs med en sekundär global MOE. På basis av nämnda fiberorienteringsdata och denna jämförelse genereras en uppskattad lokal elasticitetsmodul, MOE, i nämnda längdriktning för ett flertal underpartier. Dessa data kan användas för exempelvis tillförlitlig hållfasthetsgradering av träbrädor.

  • 21.
    Oscarsson, Jan
    et al.
    SP Sveriges Tekniska Forskningsinstitut.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Marie
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Determination of tensile strain fields in Norway spruce side boards using two master-slave connected contact-free measurement systems based on digital image correlation.2011In: Proceedings (Poster session) of the 17th International Nondestructive Testing and Evaluation of Wood Symposium, Sopron, Hungary, September 14-16, 2011., 2011Conference paper (Refereed)
    Abstract [en]

    A sample of nine Norway spruce side boards of narrow dimensions were tested in tension according to the standard EN 408. Strain fields were simultaneously measured using two master-slave connected measurement systems based on digital image correlation (DIC). Each system performed a separate measurement project measuring about 50% of the measurable length of each board and the results were combined, visualized and evaluated as one project using specific DIC software. The objectives were to investigate the possibility of measuring strain fields by use of multi-system measurements, to analyze the strain field distribution and to investigate the possibility of determining local modulus of elasticity (MOE) using strain field measurements. The results show that longitudinal strain fields were useful for identification of areas with reduced stiffness, that lateral board displacements, measured by the DIC systems, can be applied for identification of local defects, and that strain fields can be used for local MOE determination.

  • 22.
    Oscarsson, Jan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Marie
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strength grading of narrow dimension Norway spruce side boards in the wet state using first axial resonance frequency2011In: International Wood Products Journal, ISSN 2042-6445, Vol. 2, no 2, 108-114 p.Article in journal (Refereed)
    Abstract [en]

    Strength grading of Norway spruce (Picea abies (L.) Karst.) side boards in the wet state was investigated. For a sample of 58 boards, density and dynamic modulus of elasticity in the axial direction, MOEdyn, were determined in the wet state. The boards were then split into two parts and the procedure of determining MOEdyn was repeated both before and after the boards were dried to a target moisture content of 12 %. Finally, tensile strength of the split boards was measured and its relationship to MOEdyn for both wet and dried split boards determined. The investigation also included an evaluation of a so called reversed lamination effect on the stiffness caused by the splitting of boards into two parts. The results show that strength grading of split boards in the wet state can give just as good results as grading performed after drying. The reversed lamination effect on the stiffness of split boards was found to be of lower order.

  • 23.
    Oscarsson, Jan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Marie
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Strength grading of wet Norway spruce side boards by use of axial dynamic excitation2010In: Proceedings of the 2010 World Conference on Timber Engineering, Riva del Garda, Trento, Italy, June 20-24 / [ed] Ario Ceccotti, 2010Conference paper (Refereed)
    Abstract [en]

    Strength grading of Norway spruce side boards in the wet state was investigated. For a batch of 58 boards, densities and dynamic modulus of elasticity in the axial direction, MOEdyn, were determined in the wet state. The boards were then split into two parts and the procedure of determining MOEdyn was repeated both before and after the boards were dried to a target moisture content of 12 %. Tensile strength of the split boards was measured and its relation to MOEdyn for both split and unsplit boards determined. A so called reversed lamination effect on the stiffness caused by the splitting of boards into two parts was also evaluated. The results show that strength grading of split boards in the wet state could give just as good results as grading performed after drying. The reversed lamination effect on the stiffness of split boards was found to be of lower order.

  • 24.
    Oscarsson, Jan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Marie
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Strength grading of wet Norway spruce side boards for use as laminations in wet-glued laminated beams2010In: Proceedings of the final conference of COST action E53, 4-7 May 2010, Edinburgh, Scotland, 2010., 2010Conference paper (Other academic)
    Abstract [en]

    Strength grading of Norway spruce side boards in the wet state was investigated. For a sample of 58 boards of dimensions 25×120×3000 mm3, density and dynamic modulus of elasticity in the axial direction, MOEdyn, were determined in the wet state. The boards were then split into two parts and the procedure of determining MOEdyn was repeated both before and after the boards were dried to a target moisture content of 12 %. Tensile strength of the split boards was finally measured and its relation to MOEdyn for both split and unsplit boards determined. The investigation also included an evaluation of a so called reversed lamination effect on the stiffness caused by the splitting of boards into two parts. The results show that strength grading of split boards in the wet state could give just as good results as grading performed after drying. The coefficient of determination between MOEdyn in wet and dried states was as high as R2=0.92, and the relation between MOEdyn in the wet state and tensile strength in the dried state, σt, was of the same order (R2=0.55) as the relation between MOEdyn in the dried state and σt (R2=0.52). Regarding the reversed lamination effect on the stiffness of split boards, it was found to be of low order.

  • 25.
    Oscarsson, Jan
    et al.
    SP Technical Research Institute of Sweden.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Identification of weak sections in glulam beams using calculated stiffness profiles based on lamination surface scanning2014In: Proceedings of the 2014 World Conference on Timber Engineering, Quebec, Canada, 10-14 August, Université Laval , 2014Conference paper (Refereed)
    Abstract [en]

    Models for estimation of structural properties of glued laminated timber (glulam) are generally based on the relationship between properties of the individual laminations and the properties of the glulam. In this investigation, a recently presented machine strength grading method based on laser scanning of fibre direction fields was applied for determination of axial modulus of elasticity (MOE) profiles along glulam laminations. These profiles were then used to calculate edgewise bending MOE (EB) profiles of glulam beams. The objectives were to investigate the relationship between position of bending failure and position of lowest EB value along investigated beams, and the relationship between the mentioned EB value and bending strength of the beams. It was found that both relationships were rather weak, whereas local bending MOE determined in accordance with EN408 was predicted with high accuracy on the basis of EB profiles.

  • 26.
    Petersson, Hans
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Bengtsson, Tomas
    Blixt, Johan
    Enquist, Bertil
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Källsner, Bo
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sterley, Magdalena
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Oscarsson, Jan
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Högre värdeutbyte genom våt- och torrlimning av sågade sidobrädor till egenskapsoptimerade träprodukter för byggmarknaden2009Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The purpose of this project was to investigate the possibilities to manufacture wet-glued laminated beams for load bearing applications from Norway spruce side board lamellae and by that achieve products that are difficult to obtain from the centre yield of a log and also contribute to increased profitability in the sawmill industry.

     

    Properties such as shape stability, strength and stiffness of wet glued beams with crosssectional dimensions 50×300 mm2 and lengths 4850 and 5200 mm were analysed and compared with corresponding dry glued products. The results obtained are very promising. espite the fact that the beams were produced from a batch of unsorted boards, the performed tests showed that the product has the necessary qualities to be competitive in relation to both glued laminated timber of grade L40 and structural strength graded timber of grade C35. Requirements concerning limitations for geometrical characteristics as expressed in a proposal for a new harmonised glulam standard are also met.

     

    The bond line of the wet glued beams was analysed regarding mechanical properties such as fracture energy, local strength and wood failure percentage after cyclic boiling and drying treatments. The results showed that the bonds are able to comply with requirements concerning bond lines to be used in indoor as well as outdoor constructions for structural pplications.

     

    To be able to improve the quality of boards for use as lamellae in wet glued beams, a method for scanning the slope of grain and disturbance of grain on board surfaces was also further developed and implemented.

  • 27.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Deformationer i träbjälklag och trägolv på grund av fuktvariationer: Uppskattning med hjälp av finita elementberäkningar2011Report (Other academic)
    Abstract [sv]

    I rapporten redovisas resultaten av beräkningar med finita elementmetoden avseende deformationer i golvbjälklag och i parkettgolv på grund av fuktvariationer. Beräkningarna baseras på indata i form av den under året varierande relativa fuktigheten i omgivande luft. I rapporten ges också exempel på en förenklad handberäkningsmodell. Resultaten visar bl a att man genom reducerad ventilation och fuktåtervinning kan minska de oönskade deformationerna som kan uppstå vintertid.

  • 28.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Documentation of the Limnologen Project: Overview and Summaries of Sub Projects Results2009Report (Other academic)
    Abstract [en]

    This report gives a short introduction and overview of the research project conducted during the construction of the Limnologen-project in Växjö, Sweden. This multi-storey residential housing project has been documented in a number of sub-projects (vibrations and acoustics, sway, long term deformation, temperature and relative humidity in the structure, environmental impact of timber construction, decision making and the building process, logistics and supply chain studies and customer perception). Each sub-project is summarised and main results are highlighted.

  • 29.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Uppföljnings- och dokumentationsprojektet Limnologen: Översikt och delprojektrapporter i sammanfattning2009Report (Other academic)
    Abstract [sv]

    Rapporten ger inledningsvis en kort bakgrund och sammanfattning av de uppföljnings- och dokumentationsprojekt som genomförts vid byggandendet av sveriges högsta moderna bostadshus i trä - kv. Limnologen. De delprojekt som genomförts behandlar plan- och projekteringsprocessen, träbyggandets klimatpåverkan, montage- och logistik, stomresning, akustik, svikt, vibrationer, deformationsmätningar, slutanvändarnas attityder till träbyggandet, informationsspridning samt fukt och temperaturmätningar i massivträstommen. I korta delprojektbeskrivningar ges sammanfattningar av de olika delprojektens genomförande och uppnådda resultat.

  • 30.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Blixt, Johan
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Källsner, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Oscarsson, Jan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sterley, Magdalena
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Petersson, Hans
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Wet glued laminated beams using side boards of Norway spruce2011Report (Other academic)
    Abstract [en]

    In a previous research project, carried out during the years 2006-2008, the possibility to manufacture wet glued laminated beams using ungraded laminations of Norway spruce side boards was investigated with very promising results.

    In the project presented in this report, the performance of the wet glued beams has been further investigated and developed as regards grading of side board laminations, bond line properties and lamination finger jointing. The possibility to use scanning equipment for measurement of fibre angles and prediction of strength and stiffness of boards and beams has been studied and the procedures for technical approval and CE marking have been probed into. Studies concerning market and economy for the beams and layouts for a pilot plant and a full capacity plant, respectively, for production of such beams have also been carried out.

    The possibility to grade side boards in the wet state using axial dynamic excitation was investigated with a positive result. From such excitation, a board’s stiffness (modulus of elasticity) could be determined. Accordingly, grading criteria regarding axial stiffness, and knot size, was applied to grade side board laminations into two classes; outer and inner laminations. Strength and stiffness tests of beams manufactured from such graded laminations showed that the beams actually could challenge first rate glulam and LVL products available on the market.

    Regarding beam shape and shape stability, cross section cupping may need further attention. Even if this deformation was small, it was still visible to the naked eye. The problem could probably be overcome if the beams are dried to a moisture content of 12-14% before planing.

    Results of shear tests show that green glued bond lines can fulfil strength requirements for glulam. However, delamination requirements for service class 3 (outdoors) were not fully met. From small scale tensile testing of glued bonds it was concluded that green glued bonds with high density wood have the same tensile strength and fracture energy as dry glued bonds. For bonds with low density wood and/or small amount of adhesive, the tensile strength could be lower than for dry glued bonds, whereas the fracture energy was on a similar level.

    Strength testing of wet and dry glued finger joints demonstrated that joints glued from high density wood was significantly stronger than low density joints and that there was no significant difference between the strength of green glued joints and joints glued after drying. From X-ray measurement it was shown that the glue penetration into the wood fibres is much deeper in a green glued joint than in a joint that is glued in the dried state.

    From scanning algorithms developed within the scope of this project it is possible to obtain reasonably accurate predictions of grain-angle distributions on board surfaces as well as rather accurate descriptions of knot locations and of fibre-angle disturbances around knots. From scanning of board ends, cross section characteristics with respect to radial and tangential directions and of annual ring widths could also be determined. Finally, both board and beam stiffness were predicted from this data, with an accuracy that is comparable with the one obtained from well-reputed commercial grading systems.

  • 31.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Blyberg, Louise
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Glass-wood adhesive joints and components: Mechanical behaviour and test methods for load bearing applications2011In: Holz und glas im tragenden verbund.: Seminar, Wien, 28 April, 2011, 2011Conference paper (Other academic)
  • 32.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Load-bearing timber-glass shear walls2014In: Glass | Facade | Energy / [ed] Schneider, Jens and Weller, Bernhard, Technische Uni Dresden , 2014, 311-318 p.Conference paper (Refereed)
    Abstract [en]

    Timber-glass composite shear wall elements were manufactured with different adhesives. The elements were 1200×2400 mm in size. 12 single pane elements and one element with an insulation glass unit (IGU) were manufactured. The load bearing glass pane was in all cases made from 10 mm float glass. The elements were tested in various loading conditions, involving pure vertical load and different combinations of in-plane shear and vertical loading. The test results show that the influence of the adhesive chosen on the ultimate (buckling) load is only of minor importance. This was also confirmed by finite element analyses.

  • 33.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Compression strength perpendicular to grain in cross-laminated timber (CLT)2010In: World Conference on Timber Engineering, 2010Conference paper (Refereed)
    Abstract [en]

    The work presented involved testing of the compression strength of square specimens made from threelayer CLT. In one of the test set-ups a uniform compression over the complete square face of the specimen was used - similar to what is defined in the current European test standard for glued-laminated timber. In addition, several other test set-ups involving loading of only parts of the specimens’ square surface by line loads was investigated. The use of line loads aimed at investigating the effect of load distribution within the test specimen, and also to investigate possible boundary effects when the line load is applied close to the specimen edge. In practical design, the line load used in the tests, would correspond to the load transfer from a wall structure clamping a CLT-slab. During testing, apart from registering the load and deformation by conventional gauges, a contact-free deformation measurement system was used.

    The results show that the compression strength – defined according to Eurocode 5 as the load at which a 1% permanent set is obtained – is indeed dependent on the relative size of the load application area, its orientation relative to the surface grain direction and its distance to the edge of the specimen. Other conclusions are that test methods, test evaluation methods as well as design criteria for compression perpendicular to grain in CLT should be revisited.

  • 34.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Lund University ; SP Technical Research Institute of Sweden.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Vessby, Johan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Long term in-situ measurements of displacement, temperature and relative humidity in a multi storey residential CLT building2014In: WCTE 2014 - World Conference on Timber Engineering, Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    In a multi-storey residential housing project comprising of four 8-storey timber buildings, the bottom storeybeing designed with concrete and storeys 2-8 in timber, the vertical relative displacement, the temperature and the relativehumidity (RH) along one vertical channel in the external wall of one building has been monitored. Measurements startedduring construction and presented herein are results of 6.5 years of in-situ measurements. Displacement data was monitoredstorey-by-storey, with a sampling frequency of 1 measurement every 10-60 minutes. In another of the four buildingsadditional temperature and relative humidity measurements have been ongoing for about 5.5 years. These temperature andRH measurements were performed at six different locations in the building, at each location in eight positions through theexterior wall with a sampling frequency of 1 measurement every 15 minutes. The results show that the total verticaldisplacement over six storeys after 6.5 years of service life is approximately 23 mm as a yearly average, and over the yearthe displacement varies from this value by approximately ±2 mm. The main cause for the relative displacement is thedecrease of moisture content in the wood material leading to shrinkage after completion of the building. The resultsobtained show also that the exterior wall design of the building behaves well in terms of not comprising a general risk fordamp or mould in the timber core of the external walls.

  • 35.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Vessby, Johan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Vertical relative displacements in a medium-rise CLT-building.2010In: Structures and Architecture / [ed] Paulo J.S. Cruz, 2010Conference paper (Refereed)
  • 36.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Oscarsson, Jan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sterley, Magdalena
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Petersson, Hans
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Källsner, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Green-glued laminated beams: High performance and added value2010In: World Conference on Timber Engineering, 2010Conference paper (Refereed)
    Abstract [en]

    The work presented in this paper deals with the use of green gluing (also known as wet gluing) as a mean to overcome the difficulties in making use of side boards for structural applications. By manufacturing laminated beams from unseasoned side boards several advantages are obtained. Beams were manufactured from side boards of approximately 25 mm thickness. The board width was 120 mm. The boards were glued together with a 1-component polyurethane adhesive to form a beam cross-section of approximately 120×315 mm2. After curing, the beams were split into two halves, each approximately 55 mm wide. These 55×315 mm2 beams were then dried in a conventional kiln dryer. Finally, the beams were planed to target size, 50×300 mm2. Tests performed included beam bending tests for strength and stiffness, tests of the shape stability of the beams, tests of the integrity of the adhesive bond lines (delamination) and tests on the strength and fracture energy of the adhesive bond lines. The main results obtained show that there is a potential for the production of green-glued laminated beams with good technical performance.

  • 37.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. SP Technical Research Institute of Sweden, Borås.
    Oscarsson, Jan
    SP Technical Research Institute of Sweden, Borås.
    Sterley, Magdalena
    SP Technical Research Institute of Sweden, Borås.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Green-Glued Products for Structural Applications2014In: Materials and Joints in Timber Structures: Recent Developments of Technology, Springer, 2014, 45-55 p.Conference paper (Refereed)
    Abstract [en]

    The results from bending tests on 107 laminated, green-glued, beams manufactured from Norway spruce side boards are presented. The beams were made by face gluing 21-25 mm thick boards using a commercial one-component moisture curing polyurethane adhesive. In addition to the bending test results, results from shape stability measurements after climatic cycling and bond line strength and durability test results are also presented. The results from the bending tests show that, by applying very simple grading rules, it is possible to obtain beams with high bending strength (with a 5%-percentile characteristic value of 40,1 MPa) and substantial stiffness (mean value of 14360 MPa). Also the shape stability of the beams and the strength and the durability of the interlaminar bonds were found to be satisfactory.

  • 38.
    Serrano, Erik
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sjödin, Johan
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Dowel type joints – Influence of moisture changes and dowel surface smoothness2007In: COST Action E55, 4-5 October, 2007, Eindhoven, The Netherlands, 2007, 17s- p.Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The paper gives an overview of ongoing research and research performed during recent years at Växjö University, Sweden, within a PhD study. Results from various experimental and numerical studies relating to the behaviour of dowel-type joints are presented.

    The results are discussed in relation to the expected behaviour of the joints according to the current version of EC5. Possible implications of the results on future versions of EC5 will be discussed.

    In addition to the numerical and experimental results, also the experimental methods used are discussed in some detail. Here, contact-free deformation measurements in combination with finite element analyses, has proven to be an effective mean to study the mechanical behaviour in detail, at a high spatial resolution (complete deformation- and strain fields).

  • 39.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Vessby, Johan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Modeling of fracture in the sill plate in partially anchored shear walls2012In: Journal of Structural Engineering, ISSN 0733-9445, Vol. 138, no 10, 1285-1288 p.Article in journal (Refereed)
    Abstract [en]

    This study relates to the topic of anchorage of shear walls. At times, eccentric forces between the sheathing and the anchoring devices may be introduced in the sill plate. In severe cases, such forces may cause the sill plate to split and to fail in a brittle manner. In this study, fracture mechanics are applied to develop a simple closed-form hand-calculation expression for estimation of the ultimate load capacity of the sill plate. Finite-element analyses using both linear elastic fracture mechanics (LEFM) theory and a nonlinear fictitious crack model are also used to predict the ultimate load-bearing capacity of the sill plate. The hand-calculation model is compared with the finite-element models, and good agreement is obtained. The results obtained with the various fracture mechanics models are compared with results available from previously performed experimental tests, and again good agreement is obtained. A general conclusion is that the LEFM theory is an adequate approach for the case studied and that the hand-calculation expression developed could be useful for structural design.

  • 40.
    Serrano, Erik
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Vessby, Johan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Olsson, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Girhammar, Ulf Arne
    Luleå Tekniska Universitet.
    Källsner, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Design of Bottom Rails in Partially Anchored Shear Walls Using Fracture Mechanics2011In: Proc. CIB-W18, Meeting 44, Alghero, Italy / [ed] Blass, 2011Conference paper (Other academic)
  • 41.
    Sjödin, Johan
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Enquist, Bertil
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Contact-free measurements and numerical analyses of the strain distribution in the joint area of steel-to-timber dowel joints2006In: Holz als Roh- und WerkstoffArticle in journal (Refereed)
    Abstract [en]

    Two different dowel-type joints of differing size were loaded in tension parallel to the grain. The strain distribution in the joint area was studied using a contact-free measurement system. The results were compared with those of numerical analysis. The measurement system was found to be a valuable complement to traditional measurement techniques and also to numerical analyses performed in parametric studies. The measurements obtained were shown to be particularly useful for studying the highly nonlinear behavior of timber that is of special importance in characterizing timber dowel joints.

    Several observations of considerable interest were made on the basis of numerical results in combination with results of the contact-free measurement system. A non-uniform strain distribution in the joint area was detected, for example, and shear strains and tensile strains, both parallel and perpendicular to the grain were found to be concentrated in the areas most likely to influence the failure mode of the joint. A general observation made was that the larger size joint failed in brittle manner, an observation supported by previous research.

  • 42.
    Sjödin, Johan
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    A numerical study of methods to predict the capacity of multiple steel-timber dowel joints2008In: Holz als Roh- und Werkstoff, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 66, no 6, 447-454 p.Article in journal (Refereed)
    Abstract [en]

    In this study, two numerical methods are used to predict the load-bearing capacity of multiple steel-timber dowel joints loaded parallel to the grain. The aim was to show the possibility and the advantages of using numerical methods when designing multiple dowel-type joints.

    The results showed a good correlation to experimental results taken from the literature and to traditional joint calculations as given in Eurocode 5 (2004). The numerical methods are capable of predicting alternative dowel patterns that can be of great value, not only from a structural point of view, but also for aesthetical reasons. In addition, the numerical methods presented in this study can also be efficient tools for the structural engineer when considering complex loading situations in joints, i.e. in cases involving other loading situations than pure tension parallel to the grain.

  • 43.
    Sjödin, Johan
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Skog och träteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    A numerical study of the effects of stresses induced by moisture gradients in steel-to-timber dowel joints2006In: HolzforschungArticle in journal (Refereed)
  • 44.
    Sjödin, Johan
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    An experimental study of the effects of moisture variations and gradients in the joint area in steel-timber dowel joints2008In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 62, no 2, 243-247 p.Article in journal (Refereed)
    Abstract [en]

    This experimental study examines the influence of moisture variations on the load-bearing capacity of steeltimber dowel joints. The glulam specimens used to manufacture the joints were first exposed to controlled climate changes. After being stored in the climate chambers, holes were drilled and dowels were inserted. Then, the joints were loaded to failure. The main aim of this study was to investigate how and to what extent moisture variations and gradients in the joint area affects the load-bearing capacity in tension parallel to the grain. The load-bearing capacity was found to be reduced under these conditions when compared to reference joints. Moreover, the brittleness of the joints increased with the time the joints had been exposed to drying. Moistureinduced stresses and cracks in the joint area were found to be a possible explanation of the results. A similar interpretation was given in other studies where other structural timber elements have been studied. This raises an important question of how such moisture effects should be considered in design codes. One possibility is to include the influence of moisture-induced stresses in the k_mod factor used in Eurocode 5. Another way could be to consider this type of moisture effect as an equivalent mechanical load case.

  • 45.
    Sjödin, Johan
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Enquist, Bertil
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    An experimental and numerical study of the effect of friction in single dowel joints2008In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 66, no 5, 363-372 p.Article in journal (Refereed)
    Abstract [sv]

    The effect of friction between the dowel and the surrounding timber was studied for single dowel-type joints. The joints tested were divided into two groups of joints, where the surface of the dowels differed. For the first group, the dowels had a smooth surface and for the second group the dowels had a rough surface. A contactfree measurement technique was used in the experimental investigation. In addition to that, numerical simulations were carried out aimed at predicting the load-bearing capacity of the joints tested as well as estimating the coefficient of friction between the dowel and the surrounding timber.

    Important conclusions from this study, which are supported by previous research, are that the load-bearing capacity of single dowel-type joints increases when the surface roughness of the dowel increases. A very small scatter in the results, in terms of the load-displacement behavior, was seen in the tests with rough surface dowels. For the joints with smooth surface dowels, the elastic response as well as the plastic response varied considerably between different tests. The current version of the European timber code EC5 does not explicitly take into account the effect of friction. In order to take the effect into account embedding tests have to be performed in order to be able to consider the benefits of using dowels with rough surface.

  • 46.
    Sterley, Magdalena
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Enquist, Bertil
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Flat wise green gluing of Norway spruce for structural application2009In: International Conference on Wood Adhesives 2009 / [ed] Charles Frihart, Madison: Forest Products Society, 2009, 325-334 p.Conference paper (Refereed)
    Abstract [en]

    Unseasoned (green) Spruce timber planks with dimensions25 x 150 x 5400 mm3 were flat-wise glued with a one-componentPUR adhesive, forming laminated beams with 150 x 300 mm2 crosssection.After curing, each beam was divided in two halves and subsequentlydried. The final cross-section of the beams was thus 50 x 300mm2. The evaluation of the beams included bending stiffness andbending strength in 4-point bending and the mechanical properties ofthe adhesive bonds. The adhesive bonds were tested according toEuropean standards for glued-laminated timber (EN 392, EN 391) andaccording to ASTM D 905, but also with a special small-scale specimenfor testing the fracture properties of the adhesive bond in Mode I.The complete force vs. deformation curve, including both the ascendingand the descending parts could be obtained. The deformationswere measured with a contact-free technique, based on two camerasand white light. The equipment made it possible to register the strainin the bond line and in the adjacent wood with a high spatial resolution(0,2 mm). The strength of the bond line and the fracture energywas calculated. Results show that both the stiffness and the strength ofthe beams can comply with the requirements for glued-laminated timberclass L40. The adhesive bonds fulfill the requirements of glulam instandard EN 386. The tensile strength and fracture energy measuredwith the small specimens of green-glued bond lines is on the samelevel as of conventionally glued bond lines.

  • 47.
    Sterley, Magdalena
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Serrano, Erik
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Enquist, Bertil
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. Byggteknik.
    Fracture characterisation of green glued polyurethane adhesive bonds in Mode I2008In: Enhancing bondline performance.: Proceedings of the Final Conference in COSTE 34, Cost Action E34, Sopron , 2008, 156-166 p.Conference paper (Other academic)
  • 48.
    Sterley, Magdalena
    et al.
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building and Energy Technology.
    Fracture characterisation of green glued-polyurethane adhesive bonds in Mode I2013In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 46, no 3, 421-434 p.Article in journal (Refereed)
    Abstract [en]

    Unseasoned (green) spruce timber side boards of size 25 × 120 × 600 mm were flatwise-glued with a one-component PUR adhesive. Glued pairs of boards were then kiln-dried to 12 % moisture content. A special small-scale specimen for testing the fracture properties of the adhesive bond in Mode I was developed in order to evaluate the adhesive bond properties. The complete force versus deformation curve, including both the ascending and the descending parts, could be obtained with these small-scale specimens, enabling the strength and fracture energy of the bond line to be calculated. In addition, the fractured specimens were examined by scanning electron microscope. Results show that both the tensile strength and the fracture energy of the green glued PUR adhesive bonds were equal to those of the dry glued bonds. The methodology developed and used in the present study gives new possibilities for analysis of the mechanical behaviour of wood adhesive bonds, and particularly of their brittleness and its correlation with the type of fracture path. This is in sharp contrast to the use of standardised test methods (e.g. EN 302, ASTM D905) with specimens having relatively large glued areas. Using such types of specimens, it is not possible to obtain the complete force versus deformation response of the bond. In addition, when using such test methods, failure takes place in the wood or in the fibres near the bond, thus making it impossible to obtain detailed information about the bond line characteristics.

  • 49.
    Sterley, Magdalena
    et al.
    SP Technical Research Institute of Sweden, Stockholm.
    Serrano, Erik
    Linnaeus University, Faculty of Technology, Department of Building Technology. SP Technical Research Institute of Sweden, Stockholm.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Hornatowska, Joanna
    Innventia AB, Stockholm.
    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 adhesive2014In: Materials and Joints in Timber Structures: Recent Developments of Technology, Springer, 2014, 325-339 p.Conference 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.

  • 50.
    Tlustochowicz, Gabriela
    et al.
    Intitutionen för samhällsbyggnad och naturresurser, LTU.
    Serrano, Erik
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Steiger, René
    State-of-the-art review on timber connections with glued-insteel rods2011In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 44, no 5, 997-1020 p.Article, review/survey (Refereed)
    Abstract [en]

    Adhesive joints have been known andapplied for timber structures for decades. Hybridjoints with glued-in rods are nowadays successfullyused for both constructing new and strengtheningexisting timber structures. Since the 1980s theresearch and development of timber joints withbonded-in rods have been going on, however agreementregarding design criteria for these connectionshas not been reached. Today, connections with gluedinrods are not included in the European design code.Thus, it is desired to gather the current state ofknowledge to enable application in practice of theexisting and documented knowledge and experience.This paper summarizes practical and theoreticalapproaches from research done regarding joints withglued-in steel rods mostly in Europe and published inEnglish, German or Swedish. The review considersmanufacturing methods, mechanisms and parametersgoverning the performance and strength of thejoints, theoretical approaches and existing design recommendations.

12 1 - 50 of 53
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf