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  • 401.
    van Blokland, Joran
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Prediction of bending strength of thermally modified timber using high-resolution scanning of fibre direction2019In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 77, no 3, p. 327-340Article in journal (Refereed)
    Abstract [en]

    The market share of thermally modified wood (TMW) has increased in Europe during the past few years as an environmentally friendly and durable building product. However, TMW products of today are not permitted for use in structural applications, because the reduction in strength that is caused by thermal treatment cannot be accounted for. The purpose of this paper was to investigate the bending properties of thermally modified timber (TMT) of Norway spruce, and to explore possibilities to predict the bending properties of TMT. A sample of 100 boards from a 2X-log sawing pattern of 100 logs was thermally modified according to the ThermoWood® process, while the mirror 100 boards served as an unmodified control sample. Two non-destructive methods were employed: (1) a novel method based on scanning of fibre directions to obtain the lowest edgewise bending modulus of elasticity (MOE) along a board, and (2) a conventional excitation method to determine the first axial resonance frequency used to calculate the axial dynamic MOE. Finally, the boards were bent to failure according to European standard EN 408. Despite the fact that bending strength was reduced by 42% due to thermal treatment, the type and location of failure in TMT remained related to the presence of knots. Prediction of bending strength based on local fibre direction and axial dynamic MOE, gave coefficients of determination of 0.51 for the thermally modified boards and 0.69 for the control boards, whereas axial dynamic MOE alone gave 0.46 and 0.57, respectively. These results indicate that although Norway spruce TMT has lower bending strength compared to unmodified timber, predictions of the bending strength can be made with good accuracy.

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  • 402.
    van Blokland, Joran
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oscarsson, Jan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Daniel, Geoffrey
    Swedish university of agricultural sciences, Sweden.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Crack formation, strain distribution and fracture surfaces around knots in thermally modified timber loaded in static bending2020In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, p. 1-28Article in journal (Refereed)
    Abstract [en]

    The effect of thermal modification (TM) on the chemistry, anatomy and mechanical properties of wood is often investigated using small clear samples. Little is known on the effect of growth-related and processing defects, such as knots and checks, on the bending strength and stiffness of thermally modified timber (TMT). Nine boards of Norway spruce with different combinations of knot types were used to study the combined effects of checks and knots on the bending behaviour of TMT. Digital image correlation (DIC) measurements on board surfaces at sites of knots subjected to bending allowed to study strain distribution and localise cracks prior to and after TM, and to monitor development of fracture (around knots) in TMT to failure. DIC confirmed that checking in knots was increased after TM compared to kiln-dried timber, specifically for intergrown knots and intergrown parts of encased knots. Effects appear local and do not affect board bending stiffness at these sites. Bending failure in TMT initiated mainly at knot interfaces or besides knots and fractures often propagated from checks. Scanning electron microscopy analyses of fracture surfaces confirmed this, and fractures were typically initiated around knots and at knot interfaces due to crack propagation along the grain in the longitudinal–radial plane (TL fracture) under mixed mode I and II loading, such that boards failed in simple tension like unmodified timber. Images of fracture surfaces at the ultrastructural level revealed details of the brittle behaviour of TM wood. This was especially apparent from the smooth appearance of transwall failure under mode I loading across the grain.

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  • 403.
    Venna, Elin
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lundin, Carolina
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Anpassning av gammalt till äldre2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    People live longer and the older generation is also generally more active than before. This also increases the need for custom housing that meets these demands. An example of such accommodation is secure housing (trygghetsboende). There are rules and requirements for the design of a secure housing, but it does not automatically mean that the accommodation reaches the purpose it is intended for, an accommodation that can enhance the quality of life, contribute to togetherness, feel safe and an accommodation to enjoy. The purpose of this study is to create a secure housing that contributes to an increased quality of life and is experienced pleasantly and safely. The goal is to identify which factors that contribute to this, and then exemplify it in a design proposal. A qualitative method in the form of a case study with interviews was conducted to answer the goal and purpose behind this study.

    Central location and accessible designed indoor environment and outdoor environment were factors that contributed to well-being and security while independence, good health, social cohesion and proximity to friends and family raised the quality of life. Factors that contribute to increased quality of life and to what is comfortable and safe are very subjective. All people are different and safe living can mean many different things. However, the factors that emerged in the results are consistent with scientific studies made in the area. This means that the results of this work can be used as support for new construction or conversion to a secure housing. 

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  • 404.
    Vessby, Johan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Directional dependency in an OSB sheathing-to-framing mechanical connection2014Conference paper (Refereed)
    Abstract [en]

    Nailed connections are commonly employed for connecting sheathings to the framing used in shear walls. Although many aspects of such connections have been investigated thoroughly within the research community generally, the effect the loading direction has on connections of this sort has been much less investigated. In the present study experimental tests were carried out for determining in detail the effects the loading has on different sheathing-to-framing connections. The results obtained indicated the degree of loading to which a nail fastened to an oriented strand board (OSB) sheathing is subjected to not be strongly affected by which of the two main loading directions is involved, but that the effects of loading direction are found to be much greater if the timber element in question is also included in the testing carried out. The dependency of the loading effect on the loading direction at different loading stages and for different directions - parallel to the fibres, perpendicular to them, at some angle between these two main directions - was investigated here.

  • 405.
    Vessby, Johan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Florisson, Sara
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Habite, Tadios
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Numerical simulation of moisture driven fracture in mechanical timber connection using XFEM2017In: CompWood 2017 ECCOMAS Thematic Conference on Computational Methods in Wood Mechanics – from Material Properties to Timber Structures, Vienna, Austria, June 7-9, 2017, TuVerlag , 2017, p. 25-25Conference paper (Refereed)
    Abstract [en]

    Structural timber and glulam elements are an appealing alternative when it comes to choosing between structural elements as load bearing parts in e.g. halls, arenas and residential buildings. The wooden material is relatively strong in respect to its weight and its stiffness is sufficient enough to allow its use in a wide range of applications. However, there are also challenges associated with handling the material, one of which is the dimensional instability associated with moisture changes. The effect of climate variations on moisture induced deformations, stresses and failure in timber structures has already been addressed by several researchers, see e.g. [1] and [2]. A numerical model developed in the finite element package Abaqus is proposed herein to simulate crack propagation caused by variation in climate. In mechanical connections moisture induced strains in combination with boundary conditions that introduces constraints can lead to crack development and in turn weakening of wooden structures. Previous application of fracture mechanics typically focused on crack development caused by pure mechanical loading, see e.g. [3] for methods summarized and typical applications. Within the scope of the current work a numerical model is presented to simulate moisture driven crack growth within the beam/column dowel group connection shown in Figure 1. The model consists of two dimensional hygro-mechanical plane stress and XFEM analysis coupled to a nonlinear transient moisture flow analysis. A visualization of the considered problem is given in Figure 1. This figure shows a beam to column connection, which is exposed to natural climate variation (a). A schematic description of the problem is shown in Figure 1 (b). Figure 1 (c) shows simulated moisture content gradient and significant cracked beam because of the deformation constraints imposed by the dowels. The transient non-linear moisture flow was modelled using Fick’s law of orthotropic diffusion, using different diffusion coefficient in the two main directions, the length direction of the beam (assumed parallel to the fibers) and the direction perpendicular to that. The moisture transport in parallel direction was taken to be dominant. The shrinkage coefficients experience different values in perpendicular and parallel direction, αperp and αpar, respectively. For the fracture model, the critical energy release rate, GIC, is set to 300 J/m2, the strength in the perpendicular direction, ft,perp, to 2.5 MPa and the stiffness perpendicular and parallel to the length directions of the fibres are Eperp= 500 MPa and Epar= 10 000 MPa respectively.

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  • 406.
    Vessby, Johan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Olsson, Anders
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Girhammar, Ulf Arne
    Luleå Univ Technol.
    Evaluation of softening behaviour of timber light-frame walls subjected to in-plane forces using simple FE models2014In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 81, p. 464-479Article in journal (Refereed)
    Abstract [en]

    The present investigation focuses on evaluating the entire load displacement relationship, especially the softening part, of light-frame wall segments subjected to in-plane monotonic forces when the load-slip curves of the individual sheathing-to-framing fasteners are considered. Different sheathing-to-framing joint characteristics, including unloading behaviour, and stud-to-rail joint characteristics are incorporated in the analyses. Two loading cases are investigated: Horizontal loading resulting in uplift of the leading stud and diagonal loading representing a fully anchored wall. Two common types of finite element (FE) models for the sheathing-to-framing joints are used for the analyses: A single spring model and a spring pair model, where the joint characteristics valid for the timber properties perpendicular and parallel to the grain are used. The maximum capacity of the wall segments is somewhat overestimated when using the spring pair model compared to that of the single spring model. The softening parts of the load displacement curves are significantly affected, regardless of whether the perpendicular or parallel characteristics of the joints are used. The results from FE simulations using models with perpendicular and parallel characteristics are compared with full scale test results for walls with a single segment loaded horizontally and diagonally. The behaviour of the wall segments subjected to horizontal loading is dominated by fastener displacements perpendicular to the bottom rail. Hence, FE models including perpendicular characteristics should be used. For diagonal loading the behaviour of the wall segments is dominated by displacements parallel to the framing members, and FE models including parallel characteristics should therefore be used. The analyses were extended to multiple segment walls resulting in the same type of behaviour as single segment walls. (C) 2014 Elsevier Ltd. All rights reserved.

  • 407.
    Vessby, Johan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Källsner, Bo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Ormarsson, Sigurdur
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Stabilisering av takkonstruktioner i trä: arbetet med ny handbok2016In: Bygg & teknik, ISSN 0281-658X, no 4, p. 60-63Article in journal (Other (popular science, discussion, etc.))
  • 408.
    Vu, Mai
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Urban vindkraft på tak2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Växjö har ett intresse att förbättra sin miljöfråga om koldioxid utsläpp genom att öka mängden av förnybara energier resurser i samhället. Detta examensarbete bär med sig detta intresse och studerar om urbana vindkraftverk på tak. Syftet med arbetet är att öka kunskap om småskaliga vindkraftverk på tak i urban miljö som vidare kan bidra till utvecklingen med förnybar vindkrafts energi i staden.

    Rapporten studerar de faktorer som rör energiproduktions fråga från småskaliga vindkraftverk på tak i urbana miljöer som vindresurser, lämpliga vindkraftverk och förhållande mellan dem med dem medförande påverkningar samt problem. Resultatet av undersökningen visar energi beteende från småskaliga vindkraftverk på en befintlig offentlig byggnad i Växjö stad.

    Undersökningen visar en låg energiproduktion som bara täcker en liten del av bygg-nadens energianvändning. Urban vindkraft behöver mer insatser och studier för en fungerande marknad som kan konkurrera ut koldioxiden.

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    Urban vindkraft på tak
  • 409.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Almkvist, Gunnar
    Swedish University of Agricultural Sciences .
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Vienna University of Technology, Austria.
    Bjurhager, Ingela
    Uppsala University.
    Rautkari, Lauri
    Aalto University, Finland.
    Gamstedt, E. Kristofer
    Uppsala University.
    The influence of chemical degradation and polyethylene glycol on moisture-dependent cell wall properties of archeological wooden objects: a case study of the Vasa shipwreck2016In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 6, p. 1103-1123Article in journal (Refereed)
    Abstract [en]

    Cell wall measures allow for direct assessment of wood modification without the adverse effect of varying density and microstructure. In this study, cell wall properties of recent and archeological oak wood from the Vasa shipwreck were investigated for cell wall stiffness, hardness and creep with respect to effects of chemical degradation, impregnation with a preservation agent, namely polyethylene glycol, and moisture. For this purpose, nanoindentation tests were performed at varying relative humidity, leading to different moisture contents in the wood samples. Concurrently, microstructural and chemical characterization of the mate- rial was conducted. Impregnated and untreated recent oak wood showed a softening effect of both moisture and preservation agent at the wood cell wall level. On the contrary, increased stiffness was found for non-impregnated Vasa oak, which can be explained by aging-related modifications in cell wall components. These effects were counteracted by the softening effect of polyethylene glycol in the impregnated Vasa material, where a lower overall stiffness was measured. The reverse effect of the preservation agent and moisture, namely increased indentation creep of the cell wall material, was revealed. The loss of acetyl groups in the hemicelluloses explained the decreased hygroscopicity of the Vasa oak. In the impregnated Vasa oak, this effect seemed to be partly counteracted by the presence of low-molecular polyethylene glycol contributing to higher hygroscopicity of the cell wall. Thus, the higher overall sorptive capacity of the impregnated Vasa material, with respect to the non-impregnated material, was detected, which has resulted in a sorptive behavior similar to that of recent oak wood. The proposed approach requires only small amounts of material, making it especially suitable for application to precious historical wooden artifacts. 

  • 410.
    Wallin, Johan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Karlsson Bäcklund, Filip
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Materialoptimering för kulvertelement i betong2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta arbete undersöks prefabricerade kulvertelement som främst används i djurstall. Arbetet utgår från Abetongs befintliga kulvertelement och elementet kontrolleras enligt dagen dimensioneringsregler. Materialoptimering av elementet beräknas och materialbesparing tas fram. Resultatet visar att det befintliga elementet uppfyller alla kontrollera normkrav. Optimeringen visar att det finns stora möjligheter att minska materialåtgången och samtidigt följa dagens dimensioneringsregler.

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  • 411.
    Wang, X. A.
    et al.
    Luleå University of Technology.
    Hagman, O.
    Luleå University of Technology.
    Sundqvist, B.
    SP Technical Research Institute of Sweden ; SP Sustainable Built Environment.
    Ormarsson, Sigurdur
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Wan, H.
    Mississippi State University, USA.
    Niemz, P.
    ETH, Switzerland.
    Impact of cold temperatures on the shear strength of Norway spruce & scots pine joints with different glues2016In: WCTE 2016 - World Conference on Timber Engineering, Vienna University of Technology , 2016Conference paper (Refereed)
    Abstract [en]

    As wood construction increasingly uses engineered wood products worldwide, concerns arise about the integrity of the wood and adhesives used. Bondline strength is a crucial issue for engineered wood applications, especially in cold climates. In this study, the impact of cold temperatures on the shear strength of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) joints (150 mm x 20 mm x 10 mm) bonded with seven commercially available adhesives was studied. The cold temperatures investigated were: 20, -20, -30, -40, -50, and -60 °C. Generally, within the temperature test range, temperature changes significantly affected the shear strength of solid wood and wood joints for both species. As the temperature decreased, the shear strength decreased. PUR adhesive in most cases resulted in the strongest shear strength and MUF adhesive resulted in the weakest. But different adhesives responded differently with Norway spruce and Scots pine.

  • 412.
    Wang, Xiaodong (Alice)
    et al.
    Luleå University of Technology, Sweden.
    Hagman, Olle
    Luleå University of Technology, Sweden.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden, Sweden.
    Ormarsson, Sigurdur
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Wan, Hui
    Mississippi State University, USA.
    Niemz, Peter
    ETH Zurich, Switzerland.
    Shear Strength of Scots Pine Wood and Glued Joints in a Cold Climate2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 1, p. 944-956Article in journal (Refereed)
    Abstract [en]

    The impact of cold temperatures on the shear strength of Scots pine (Pinus sylvestris) joints glued with seven commercially available adhesives was studied in this work. The cold temperatures investigated were: 20, -20, -30, -40, and -50 degrees C. Generally, within the temperature test range, the shear strength of Scots pine solid wood and wood joints were more resistant to the effect of temperature than those of Norway spruce. As the temperature decreased, only some of the joints' shear strength significantly decreased. In most cases, PUR adhesive yielded the strongest shear strength and MUF adhesive yielded the weakest shear strength. MF adhesive responded to temperature changes in a similar manner to that of PUR and PVAc adhesives. The shear strengths of wood joints with PRF and EPI adhesives were more sensitive to temperature change. For dynamic tests of shear strength, the values for 12-h and 6-day tests under temperature cycles (-20 and 0 degrees C) were compared. The values for 6-day tests were lower than those for 12-h tests. Therefore, the duration of the samples subjected to the same temperature had a significant impact on shear strength. Our results indicate that PUR adhesive is the most stable; whereas the stability of MUF and PRF adhesives decreased significantly.

  • 413.
    Wessels, CB
    et al.
    University of Stellenbosch, South Africa.
    Crafford, PL
    University of Stellenbosch, South Africa .
    du Toit, B
    University of Stellenbosch, South Africa.
    Grahn, T
    Innventia, Sweden.
    Johansson, Marie
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lundqvist, S-O
    Innventia, Sweden.
    Säll, Harald
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Seifert, Thomas
    Univesity of Stellenbosch, South Africa.
    Lumber properties of three drought tolerant eucalyptus species grown in arid regions of south africa2015In: IUFRO Symposium: Silviculture and Management of Dryland Forests,, 2015Conference paper (Other academic)
  • 414.
    Wessels, CB
    et al.
    University of Stellenbosch, South Africa.
    Crafford, PL
    University of Stellenbosch, South Africa.
    DuToit, B
    University of Stellenbosch, South Africa.
    Grahn, T
    Innventia AB, Stockholm.
    Johansson, Marie
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lundqvist, S-O
    Innventia AB, Stockholm.
    Säll, Harald
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Seifert, Thomas
    University of Stellenbosch, South Africa.
    Variation in physical and mechanical properties from three drought tolerant Eucalyptus species grown on the dry west coast of Southern Africa2016In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 74, no 4, p. 563-575Article in journal (Refereed)
    Abstract [en]

    Southern Africa, and specifically its western parts is dominated by low rainfall areas, and it is expected that the rainfall in most of these parts will in future decrease further due to climate change. Woodlots of fast-growing, non-invasive tree species can provide the opportunity to produce wood and release the pressure on natural woodlands, while creating much needed income to inhabitants. Over the last two decades several trials of Eucalyptus species that could potentially withstand arid conditions were established on the South African west coast. The three most promising genotypes according to their volume growth were selected among 46 pure and hybrid species from two 20-year-old trials for further evaluation. These included 10 Eucalyptus grandis × Eucalyptus camaldulensis hybrid trees, 9 Eucalyptus gomphocephala trees, and 9Eucalyptus cladocalyx trees for a total of 28 trees. The objective of the study reported here was to investigate the within-tree and between species variability of selected physical and processing properties determining the suitability of these three species for lumber production. The density, microfibril angle, spiral grain angle, MOE, MOR, radial and tangential shrinkage, twist, bow, splitting, and collapse were measured in a radial and longitudinal gradient. Valuable insights were gained which could provide decision support for planting, processing and further research on these species when grown in arid conditions. The E. grandis × camaldulensis hybrid was inferior in terms of most relevant properties to the other two species evaluated. The main shortcoming of both E. gomphocephala and E. cladocalyx was the high levels of twist in lumber.

  • 415.
    Wiberg, Frida
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Rindberg, Agnes
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Laserskanning och 3Dmodellering för rekonstruktion av ett medeltida kyrkorum2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study is describing a 3D reconstruction of a medieval church located 25 kilometers south of Växjö. The church is very special as the appearance of the building is still very original. The church also has an unusual roof construction that this project wants to point out. However, the roof structure once visible from the church room, is today hidden by a ceiling which was erected later in an indefinite time. The purpose and goal with the 3D reconstruction is to recreate the original church hall and compare it with the contemporary interior design based on three aspects; experiences of light, - the room in general and the experiences of movement patterns in the church. The result of the project showed that the church hall earlier on was much darker inside due to the lack of windows, but the church hall was on the other hand very spacious in the middle ages because the interior was not furnished during this time. Today the church has received more and larger windows and the hall is furnished with pews and a pulpit, which have led the movement pattern to an aisle from west to east in the middle of the church hall. In future projects, about churches and older constructions, this study can be used as guideline and support for further studies. It is also a study that is open for additional development, as for example the 3D reconstruction can be translated into VRtechnology, so that people can experience the medieval church as it was in the 13th century, almost like they were there.

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    Laserskanning och 3Dmodellering för rekonstruktion av ett medeltida kyrkorum
  • 416.
    Wiesner, Felix
    et al.
    University of Edinburgh, UK.
    Klippel, Michael
    ETH Zürich, Switzerland.
    Dagenais, Christian
    FPInnovations, Canada.
    Dunn, Andrew
    Timber Development Association (NSW), Australia.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Janssens, Marc
    Southwest Research Institute, USA.
    Kagiya, Koji
    Building Research Institute, Japan.
    Requirements for Engineered Wood Products and their Influence on the Structural Fire Performance2018In: WCTE2018, World Conference on Timber Engineering, 20-23 August, Seoul, Republic of Korea, World Conference on Timber Engineering (WCTE) , 2018Conference paper (Refereed)
    Abstract [en]

    Engineered wood products e.g. cross-laminated timber (CLT), glued-laminated timber (glulam) and laminated veneer lumber (LVL) are increasingly used as the material of choice for mid-rise to tall construction timber projects. However, the requirements to manufacture these timber elements are considerably different among countries and, consequently, do have an influence on their fire performance. Requirements for sizes of the boards, allowed knot sizes and structural adhesives, among others, are of particular interest. The present paper gives an overview of the production requirements for CLT, glulam and LVL in different countries and discusses how the requirements affect the fire performance of these products.

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  • 417.
    Wiktor Windblixt, Ida
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Karlsson, Maria
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Jämförelse av stegljudsisolering mellan tre olika bjälklagstyper2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sound and vibration which originate from footsteps can spread in a building and may disturb the people who residence it. Ability to insulate impact sound varies depending on how the joists system is designed and how high its stiffness and mass are. In this thesis the impact sound insulation of three different joists systems will be examined. The joists systems are installed in existing buildings located in Växjö, Sweden and owned by the real estate company Videum.

     

    The purpose of the thesis was to examine which of the three different joists systems that is most suitable for office- and university buildings, concerning acoustics. Furthermore, the purpose was to examine which of the joists systems that has the best ability to sequester impact sound horizontally. The goal with the thesis was to perform a standardized impact sound insulation measurement and a survey to determine which of the joists systems that has the best impact sound insulation. All data was analyzed and calculated.

     

    The results show that the CLT board with a concrete layer reduces the impact sound most efficiently. However, it should be mentioned that the designs of the objects are not fully comparable and therefore the results relate to the entire design including the wall floor connection, rather than to the joists systems alone.

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  • 418.
    Wu, Min
    et al.
    Technical University of Denmark, Denmark;COWI AS, Denmark.
    Fridh, Katja
    Lund University.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Geiker, Mette
    Norwegian University of Science and Technology, Norway.
    Impact of sample crushing on porosity characterization of hardened cement pastes by low temperature calorimetry: Comparison of powder and cylinder samples2018In: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 665, p. 11-19Article in journal (Refereed)
    Abstract [en]

    Theimpact of sample crushing on the detected porosity of hardened cement pastes bylow temperature calorimetry (LTC) was studied using powder and cylindersamples. Two types of cements, CEM I and CEM III were used to prepare thepastes. A model porous material, MCM-41, was also used in order to investigatesome aspects of the measurement and the evaluation approach. The powder andcylinder samples of the cement pastes were compared in terms of the calculatedice content curves, total pore volumes and pore size distribution curves. For thetwo studied cement pastes, the calculated ice content curves of freezing of thepowder sample differed from that of the cylinder samples, especially for thepaste CEM III. The results indicate that sample crushing changed the poreconnectivity as compared to non-crushed samples. One important differencebetween the powder sample and the cylinder samples of the paste CEM III wasthat the determined maximum ice content in the powder sample was much higherthan that in the cylinder samples, the relatively difference being about 40–50%.However, this kind of marked difference was not found in the paste CEM I. Theobserved difference between the calculated pore volume of the powder and thecylinder samples of the paste CEM III is possibly due to some of the “isolated”pores which, presumably, cannot be fully filled with water in the preparationof the cylinder samples. However, sample crushing makes it possible to saturatethe pores to a greater extent if the crushing contributes to open up the“isolated” pores. Consequently, more pores are detected in the powder samples.The argument that the “isolated” pores have a tendency to be opened up by thecrushing process is supported by results using gravimetric measurements and“dynamic (water) vapor sorption” measurements on powder samples.

  • 419.
    Xu, Shengmin
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Tan, Peiwei
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Glued timber connections: Experimental and numerical study of tension behavior under various influencing parameters2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Glued connections are relatively new in structural timber engineering. They are expected to show high connection stiffness as well as a high connection strength compared to mechanical connections e.g. dowel‐type connections.The main aim of this thesis is to characterize the behavior of glued timber connections under pure tension by conducting experiments as well as numerical simulations. Hereby the influence of different parameters is studied such as the geometry (bond-line length and thickness) and the material properties (e.g. adhesives of highly diverse stiffness). Additionally, reference tests on a dowel-type connection are made. The purpose is to see the differences between dowelled and glued connections and to see if there are some advantages in using glued timber connections (the base geometry was chosen acc. to Eurocode 5).Finite element models were created in the software ABAQUS. The models were used to predict the connection stiffness and compare this to the experimental results. In addition, parametric studies were performed on e.g. overlapping lengths. The comparison between experiments and simulations showed good agreement.It was found that glued connections with the adhesives SikaPower-4720 and SikaFast-5215 NT (an epoxy and an acrylate, respectively) had higher stiffness than the dowel connections, whereas connections with the silicone adhesive SikaSil SG-500 had a lower stiffness. A general conclusion drawn from this work is that the glued timber connections simulated in this project should also be suitable for application to complex connections and situations involving other loading situations than pure tension.

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  • 420.
    Yousuf, Jabran
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Rezaie, Hamed
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Fukt i material under byggskedet2017Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta arbete tar upp fuktproblemen vid materialförvaring samt vid leverans. Fokus i arbetet ligger på trämaterial, dock har även andra byggnadmaterial tagits upp. Fuktmätningar och intervjuer på byggarbetsplatser har gjorts för att få en bild på hur byggnadsmaterialet hanteras på byggarbetsplatser. Arbetet visar att beställaren kan ha en stor påverkan på hur byggnadsmaterialet hanteras på byggarbetsplatserna.

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  • 421.
    Åkesson, Henrik
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Larsson, Johan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Undersökning av reaktionskrafter i upplagen avseende olika brottmoder i ett kompositbjälklag bestående av TP-plåt och trä2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Ett kompositbjälklag av trapetskorrugerade plåtar sammansatta med reglar och glespanel studeras. Bjälklaget ska vara bärande i två riktningar för att på så sätt uppnå konkurrenskraftig prestanda jämfört med andra bjälklagstyper. Arbetet undersöker de båda bärriktningarnas upplagskapaciteter för att på så sätt ge underlag om praktiskt tillämpbara spännvidder. Svaga punkter/delar redovisas också för att ge underlag om i vilken prioritetsordning förbättringar kan göras.

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  • 422.
    Öberg, Marcus
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Valdebenito, Marcelo
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Staden i Arenastaden2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Ett mycket högexploaterat förslag utformas där en egen identitet skapas åt Arenastaden i Växjö. Solens gång, bullerkällor, brandrisker, kulturhistoriska värden och många mål i kommunens visionsbild för Arenastaden väger in vid utformning av förslaget. Förslagets nya upplevelsevärden och andra kvalitéer analyseras med hjälp av en solstudie, bullerkällsundersökning och analysmetod av Kevin Lynch. Projektuppgiften är baserad på att en mycket hög exploatering drar ner på områdets upplevelsevärden. Då analysens resultat föll annorlunda erhölls ett annat resultat – metoden; att bygga på höjden besparar grönytor och de värden som mäts vid en Lynchanalys.

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    Staden i Arenastaden
  • 423.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandsäkra träfasader: europeisk översikt2019In: Bygg & teknik, ISSN 0281-658X, no 8, p. 46-48Article in journal (Other (popular science, discussion, etc.))
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  • 424.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Europeisk brandklassning av CLT och LVL2017In: Bygg & teknik, ISSN 0281-658X, Vol. 109, no 6, p. 55-57Article in journal (Other academic)
    Abstract [sv]

    Den europeiska brandklassningen av träbaserade produkter har nyligen utvidgats till att gälla även de två relativt nya träprodukterna CLT och LVL. Den täcker därmed praktiskt taget alla byggtillämpningar med träbaserade produkter. Brandklasserna har fastlagts genom ett system för förenklad europeisk brandklassificering för produkter som har ”känt och stabilt beteende vid brand”. Träprodukter är ett utmärkt exempel på sådana produkter. Brandklasserna avser både det europeiska systemet med så kallade Euroklasser A1-F och klasser för brandskyddande förmåga, så kallade K-klasser, se faktaruta.

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  • 425.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Fire performance of wood products and timber structures2017In: International Wood Products Journal, ISSN 2042-6445, E-ISSN 2042-6453, Vol. 8, no 2, p. 74-79Article in journal (Refereed)
    Abstract [en]

    An overview of the European requirements on fire safety in buildings is presented based on the construction products regulation and its essential requirements. These requirements are mandatory, to be used in all countries. They include classification systems for reaction to fire of building products, fire resistance of building elements and structural Eurocodes. The reaction-to-fire performance of wood products in accordance with the European classification system is given. Euroclass D is usually achieved. Higher classes can be reached by chemical treatments, but the durability of the reaction-to-fire performance needs to be fulfilled according to a new European system. The fire resistance of building elements can be either tested according to the European standards or calculated using design methods according to Eurocode 5, EN 1995-1-2. Both separating and load-bearing structures are included. Timber structures can obtain high fire resistance, e.g. REI 60, REI 90 or even higher.

  • 426.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Fire safety in modern wooden houses: mapping of fire incidents in Sweden2017In: International fire protection, ISSN 1468-3873, no 71, p. 46-48Article in journal (Other academic)
    Abstract [en]

    Multi-storey timber frame houses have been built in Sweden since 1994, when performance-based building regulations were introduced. The construction technology is now well established and steadily growing. Life safety protection is clearly defined in the building regulations. Now, property protection is being discussed from new perspectives.

    As a first step in better understanding, fire incidents have been mapped. The survey shows that modern apartment buildings with wooden frames have a lower rate of fire incidents than the entire stock of apartment buildings.

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  • 427.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Olika internationella krav på KL-trä påverkar den brandtekniska dimensioneringen2019In: Bygg & teknik, ISSN 0281-658X, no 6, p. 30-32Article in journal (Other (popular science, discussion, etc.))
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  • 428.
    Östman, Birgit
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Weathering Effects on Fire Retardant Wood Treatments2019In: Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires: Living edition / [ed] Samuel L. Manzello, Cham: Springer, 2019Chapter in book (Refereed)
  • 429.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandon, Daniel
    SP/RISE Research Institutes of Sweden.
    Frantzich, Håkan
    Lund University.
    Fire safety engineering in timber buildings2017In: Book of Abstracts Papers: Invited papers, 2017, p. 11-Conference paper (Refereed)
    Abstract [en]

    The combustibility of timber is one of the main reasons that many building regulations strictly limit the use of timber as a building material. Fire safety is an important contribution to feeling safe, and an important criterion for the choice of building materials. Historically, the combustibility aspect of wood has been a disadvantage for using timber as a construction material. The main precondition for an increased use of timber in buildings is providing adequate fire safety. This paper reviews the opportunities and challenges to reach this goal by implementing Fire Safety Engineering and Performance Based Design principles.

  • 430.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandon, Daniel
    SP/RISE Research Institues of Sweden.
    Frantzich, Håkan
    Lund University.
    Fire safety engineering in timber buildings2017In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 91, no Special Issue, p. 11-20Article in journal (Refereed)
    Abstract [en]

    The combustibility of timber is one of the main reasons that many building regulations strictly limit the use of timber as a building material. Fire safety is an important contribution to feeling safe, and an important criterion for the choice of building materials. Historically, the combustibility aspect of wood has been a disadvantage for using timber as a construction material. The main precondition for an increased use of timber in buildings is providing adequate fire safety. This paper reviews the opportunities and challenges to reach this goal by implementing Fire Safety Engineering and Performance Based Design principles.

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  • 431.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandon, Daniel
    RISE Reasearch Institutes of Sweden.
    Just, Alar
    RISE Reasearch Institutes of Sweden.
    Brandteknisk dimensionering av CLT-konstruktioner2018In: Bygg & teknik, ISSN 0281-658X, no 6, p. 50-53Article in journal (Other academic)
    Abstract [sv]

    CLT, korslaminerat trä eller KL-trä som det ofta kallas i Sverige är en relativt ny byggprodukt som snabbt blivit känd och uppskattad runt om i världen. Den används främst till stommar i både höga och låga byggnader och bidrar till stabilieringen som är viktig särskilt i högre byggnader.

    Brandegenskaperna hos CLT som synligt material i byggnader har klarlagts (Östman B&t 2017), medan forskning om brandteknisk dimensionering av CLT-konstruktioner fortfarande pågår. Denna artikel sammanfattar nuläget.

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  • 432.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandon, Daniel
    RISE, Sweden.
    Just, Alar
    RISE, Sweden.
    Riktlinjer för egendomsskydd i höga trähus2018In: Bygg & teknik, ISSN 0281-658X, no 6, p. 64-66Article in journal (Other academic)
    Abstract [sv]

    Riktlinjer för att minska risken för egendomsskador i flervånings byggnader med trästomme har tagits fram i ett Brandforskprojekt. Riktlinjerna sammanfattas här och är främst tillämpbara för byggnadsklasserna Br1 och Br0 enligt Boverketes byggregler (BBR), men är naturligtvis användbara även för mindre byggnader. Mer utförliga riktlinjer ges i en RISE rapport 2018:46.

    En första del av detta arbete var brandstopp i modulbyggnader, som presenterades i Bygg & teknik 2016.

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  • 433.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Just, Alar
    RISE, Sweden.
    Brandon, Daniel
    RISE, Sweden.
    Branddimensionering av Br0-byggnader med trästomme2019In: Bygg & teknik, ISSN 0281-658X, no 6, p. 24-29Article in journal (Other (popular science, discussion, etc.))
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  • 434.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Mikkola, Esko
    Fire safety of bio-based facades2019In: FSF 2019 3rd international symposium on fire safety of facades, Paris, 2019Conference paper (Other academic)
  • 435.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Mikkola, Esko
    KK-Palokonsultti Oy, Finland.
    Guidance on Fire Safety of Bio-Based Facades: COST Action FP 1404,  “Fire Safe Use of Bio-Based Building Products”2018Report (Other academic)
    Abstract [en]

    The use of wooden facade claddings and bio-based insulation materials in external walls are increasing because of esthetical and sustainability reasons. The introduction of performance-based building codes has generally facilitated the wider use of these materials and products in multi-storey buildings, but the use of visible woodas exterior facade claddings is still limited.

    Key initiating events of facade fires are a) interior fire spreading to external wall system via external openings,b) exterior fire directly adjacent external wall system igniting the wall due to radiant heat and/or flame impingement,and c) exterior fire spatially separated from external wall system resulting from radiant heat.

    Contribution of bio-based façade claddings and insulation materials to fire development and spread can beprevented by using protective methods. Examples of these are protection of insulation products by coverings or layers made of materials with good reaction to fire performance and/or with a sufficient protection capacity and/or prevention of facade cladding fires by hindering flames from a flashover room fire by using fire rated windows, automatic window shutters or sprinklers. Fire stops in ventilation cavities or in order to interrupt acombustible insulation are also effective means of fire protection.

    Several wooden facade systems do fulfil at least the European reaction to fire class D-s2, d0. Based on fullscale test results some conclusions and recommendations have been made concerning proper criteria and possible area limits of wooden facades.

    Fire retardant treated wood may be used, but the durability of the fire retardant treatments at exterior weather conditions need to be demonstrated in addition to the fire behaviour. The new European standard EN 16755for testing and classification of fire retardant treated timber products durability is suitable for this purpose.

    This Guidance document on fire safety of bio-based facades is the result of work within several Task Groupsof the COST Action FP1404 “Fire Safe Use of Bio-Based Building Products” and aims at a common understanding of issues related to the description, design and fire testing facades

  • 436.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Schmid, Joachim
    Klippel, Michael
    Swiss Fed Inst Technol, Switzerland.
    Just, Alar
    TUT, Estonia;RISE Tech Res Inst Sweden.
    Werther, Norman
    Tech Univ Munich, Germany.
    Brandon, Daniel
    RISE Tech Res Inst Sweden.
    Fire Design of CLT in Europe2018In: Wood and Fiber Science, ISSN 0735-6161, Vol. 50, p. 68-82Article in journal (Refereed)
    Abstract [en]

    The fire safety design of cross-laminated timber (CLT or X-Lam) in Europe is governed by the Construction Products Regulation and its essential requirements, as for all other building products. These requirements are mandatory, to be used in all European countries. They include classification systems for reaction to fire of building products, fire resistance of building elements, and structural Eurocodes. The reaction-to-fire performance of CLT in accordance with the European classification system is specified. Higher classes can be reached by chemical treatments, but the durability of the reaction-to-fire performance needs to be fulfilled according to a new European system. The fire resistance design of CLT building elements is not included in Eurocode 5, the structural Eurocode for timber, but can be either tested according to European standards or calculated by using design methods being developed recently. This article provides information about both reaction to fire and fire resistance of CLT in Europe. Furthermore, the importance of proper detailing in building design and in practice is stressed. Finally, performance-based design is introduced and some further research needs suggested.

  • 437.
    Östman, Birgit
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Tsantaridis, L D
    SP/RISE Technical Research Institutes of Sweden.
    Durability of the reaction to fire performance of fire-retardant-treated wood products in exterior applications: a 10-year report2017In: International Wood Products Journal, ISSN 2042-6445, E-ISSN 2042-6453, Vol. 8, no 2, p. 94-100Article in journal (Refereed)
    Abstract [en]

    Fire retardants may considerably improve the reaction to fire properties of wood products, but the long term durability needs to be addressed. Several long term studies of fire retardant treated (FRT) wood products over time are presented. They are performed according to a European system based on earlier Nordic and North American systems and include accelerated aging according to different procedures and natural weathering up to 10 years.

    Main conclusions are:

    • The hygroscopic properties are unchanged compared to untreated wood products for most FRT wood products studied and used commercially

    • The reaction to fire properties of FRT wood may be maintained after accelerated and natural aging if the The hygroscopic properties are unchanged compared to untreated wood for most FRT wood retention levels are high enough, but several products lose most of their improved reaction to fire properties during weathering

    • Paint systems contribute considerably to weather protection and are usually needed to maintain the reaction to fire performance at exterior applications

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