| 1. |
- Bolmsvik, Åsa, 1975-, et al.
(författare)
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Vibration Distribution Due to Continous, Intermittent or Half Embedded Elastomer Connections in Wooden Constructions
- 2016
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Ingår i: Proceeding of the 2016 World Conference on Timber Engineering (WCTE), August 22-25, 2016 Vienna. - Vienna : TU-MV Media Verlag. - 9783903039001 - 9783903024359 ; , s. 2912-2920
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Konferensbidrag (refereegranskat)abstract
- Elastomers are commonly used to decrease the sound transmission between apartments in timber framed houses. In previous studies, different types of elastomers have been evaluated experimentally. The wooden assemblies, in which elastomers were used in the connections, showed that elastomers cause the vibrations to increase in the direction perpendicular to the applied load within the low frequency span.In this study, the effects on acceleration, depending on how the elastomers are placed are studied. The cases having the elastomer continuous, placed as intermittent pieces or positioned half embedded in the junctions are evaluated.The frequency dependent properties of the elastomers are needed in order to model the dynamic behaviour and thereby be able to predict sound- and vibration transmission in wooden houses. Here, the properties of a wooden construction having different elastomers connections are studied to enable simulations of the behaviour of the elastomers in a FE model in the future.
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| 2. |
- Florisson, Sara, et al.
(författare)
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A numerical study of the effect of green-state moisture content on stress development in timber boards during drying
- 2019
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Ingår i: Wood and Fiber Science. - : Society of Wood Science and Technology. - 0735-6161. ; 51:1, s. 41-57
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Tidskriftsartikel (refereegranskat)abstract
- Timber boards manufactured with a traditional sawing pattern often contain both heartwood andsapwood. In such boards, internal constraints can occur during drying because of a radial variation in greenstate(GS) MC between the heartwood (30-60%) and sapwood region (120-200%). Despite such knowledge,the initial MC is seldom considered when evaluating kiln-drying schedules. The effect of GS MC on thedevelopment of tangential tensile stress during drying is studied for four types of timber boards. A numericalmodel was developed that can simulate transient nonlinear orthotropic moisture flow and moisture–inducedstress and distortion in wood with the use of the finite element method. The stress analysis considers elastic,hygroscopic, and mechano-sorptive strain. The study shows that the GS MC does not significantly influencethe maximum stress state, but that it does influence the time at which the maximum tangential tensile stressoccurs at different exchange surfaces. This results in several periods in the drying schedule where unfavorablehigh stress situations in the tangential direction arise, which could lead to crack propagation.
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| 3. |
- Florisson, Sara, et al.
(författare)
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Modelling of mechano-sorption in clear wood by using an orthotropic non-linear moisture flow and stress model
- 2018
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Ingår i: WCTE 2018 - World Conference on Timber Engineering. - : World Conference on Timber Engineering (WCTE).
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Konferensbidrag (refereegranskat)abstract
- The European design standard for timber structures provides, besides obligatory safety requirements, a set of general serviceability requirements. Despite their generality, they have been proven important in design of timber structures, especially in varying climatic conditions, where the time dependent deflection can have a dominant role in long term performance. The total deformation consists of instantaneous elastic deformation, hygroscopic deformation, time dependent creep and mechano-sorptive deformation. The three latter deformations are influenced by climate, and when the change in climate is considerable over time, the deflection will significantly increase. In this paper a test-setup is created to study the effect of mechano-sorption on the global deflection of clear wood samples. The samples are loaded in a three-point bending test subjected to a constant mechanical load combined with a cyclic climatic load. The moisture induced stress and bending distortion were simulated by taking into account elastic, hygroscopic and mechano-sorptive strain. The non-linear moisture flow was simulated using Fick’s law. A parametric study was performed to obtain a better understanding of the constitutive equation, especially the term related to the moisture and temperature dependent diffusion coefficient. In addition to the simulations, an experiment was performed to verify the global deflection and mass change. The obtained results show that the mechano-sorption behaviour of the tested clear wood samples can be modelled, but an improvement of both the experimental setup and the model is required to come to more accurate conclusions on this type of long-term material behaviour.
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| 4. |
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| 5. |
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| 6. |
- Jára, Robert, et al.
(författare)
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Navrhování spojů dřevěných prvků za pomoci kování
- 2016
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Ingår i: Dřevostavby 2016. - Volyně. - 9788086837840 ; , s. 187-189
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Článek je zaměřen na řešení problematiky spojů dřevěných prvků za pomoci tenkostěnných ocelových elementů aneb kování, kde jako spojovací prvek jsou použity kolíkové spojovací prostředky.
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| 7. |
- Kuklík, Petr, et al.
(författare)
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Úhelníky s prolisem ve spojích dřevěných prvků
- 2015
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Ingår i: Sympozium Energeticky efektivní budovy 2015. - Prague : Společnost pro techniku prostředí. - 9788002026150 ; , s. 149-154
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper presents load-bearing capacity calculation methods for timber elements connections by angle brackets with a rib. As connectors, annular ring nails were used. Paper brings direct comparison of results from full-scale tests, analytical calculations and numerical simulations of connections under the external load using two different versions of brackets.
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| 8. |
- Nilsson, Jonaz, 1970-, et al.
(författare)
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Moisture-related distortion and damage of lightweight wood panels : experimental and numerical study
- 2017
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Ingår i: Journal of the Indian Academy of Wood Science. - : Springer. - 0972-172X .- 0976-8432. ; 14:2, s. 99-109
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Tidskriftsartikel (refereegranskat)abstract
- This study was conducted to increase the knowledge of moisture-related distortion and damage in the field of wood-based lightweight panels. By increasing the possibilities of predicting moisture-related distortion and damage, the possibilities of using lightweight wood materials could increase. The study was performed through experiments and modelling work on a wooden panel product with numerous struts and two thin outer-face sheets of beech-wood glued tightly onto the struts, as well as reference panels of solid wood. During the testing period the results showed the density of the studied lightweight panels to vary from 170 to 290 kg/m3. These panels shrunk and swelled less than the solid wood panels and reacted faster to changes of surrounding humidity and temperature. Moisture related distortions such as twist and bow were not inferior compared to the solid wood panels. Shrinkage or swelling produced moisture related stresses. This may mean that the panel will have a risk of serious damage in the form of cracks or glue release between the outer face sheet and the struts when it is exposed to intense drying. The experimental tests also followed how various damages arose in the panels. Until the damage occurred, the deformation results showed a strong agreement between the experimental and the model findings. Better knowledge of how this type of panel reacts to climate variations is important for the further design and development of this type of product.
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| 9. |
- Ormarsson, Sigurdur, 1963-, et al.
(författare)
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FE-modell av en volymmodul - spännings- och stabilitetsanalys : Förstudie
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trä är ett mycket användbart, prisvärt och förnyelsebart material som rätt utnyttjat har en extremt hög industriell potential inom området byggnadskonstruktion. Det finns ett stort intresse i Sverige att utforska nya sätt att utnyttja trä som huvudlastbärande material i olika typer av flervåningshus. Detta är en stor utmaning för träbyggnadsindustrin, forskare och konstruktörer eftersom det inte finns någon traditionell beräknings- och designprocedur för dessa typer av byggnader.I denna förstudie har en parametrisk FE-modell framtagits för att studera strukturmekaniska egenskaper (deformationer och styvhet) hos en typisk volymmodul som används för byggande av flerbostadshus i trä. Modellen är uppbyggd av olika typer av strukturelement (fjädrar, balk- och skalelement) för att den skall vara så snabb och flexibel som möjligt. Modellen inkluderar ett stort antal konnektor- och kopplingselement för att på ett optimalt sätt kunna simulera alla spik-, skruv- och bultförband i modulen. Modellen är också ganska flexibel eftersom den är parameterstyrd via ett antal geometriska parametrar. Modellen har använts för att studera globala deformationer och styvhetsegenskaper hos olika vägg- och volymelement när de belastas med olika mekaniska laster. Att få en uppfattning om hur styvhetsegenskaper hos de mekaniska förbanden (svaga delar i konstruktionen) påverkar det globala deformationsbeteendet hos olika vägg- och volymelement har varit en viktig del i denna förstudie.Modellen visar ett deformationsbeteende hos vägg- och volymelementen verkar rimliga men en experimentell verifiering återstår. Ett exempel på resultat är att väggelement som belastas i planskjuvning har en tydlig tendens att böja ut ur planet eftersom det finns gipsskiva enbart på insidan av regelstommen. Studien visar också att för volymmoduler med en gles skruvförbindning mellan vägg- och bjälklagselementen uppkommer stora gliddeformationer mellan elementen. En av de viktigaste slutsatser från denna förstudie är att det gick att skapa en snabb och effektiv strukturmekanisk tredimensionell FE-modell för den här typen av konstruktion. Beräkningstiden för en volymmodul var endast 5.5 minuter på en vanlig laptop computer. Dessa resultat visar därför att det finns goda förutsättningar för att kunna simulera och analysera hela flerbostadshus inom rimliga beräkningstider.
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| 10. |
- Ormarsson, Sigurdur, 1963-, et al.
(författare)
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Finite element simulation of global structural behaviour of multifamily timber buildings using prefabricated volume modules
- 2018
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Ingår i: WCTE 2018 - World Conference on Timber Engineering. - : World Conference on Timber Engineering (WCTE).
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Konferensbidrag (refereegranskat)abstract
- The potential of building multi-storey timber buildings has changed in recent decades. The building of apartment houses with fully prefabricated volume modules in wood is an industry sector that is rapidly increasing its capacity. A number of house manufacturers that have delivered volume modules, primarily for single family homes, are now expanding their production to multi-storey buildings with up to 6-8 floors. This is a challenging task for producers, since the available design procedures for timber buildings have not yet been fully implemented for these types of buildings. The aim of the work is to develop an efficient and flexible finite element model to analyse the three-dimensional structural behaviour of multi-storey buildings using prefabricated volume modules, made from wooden stud-and-rail structures. The model will be used to study the global structural behaviour of various timber walls, volume modulus and modular-based multi-storey buildings when subjected to different types of loading. The model will also be used for detailed analysis and design (using so-called adaptive modelling) of the most critical parts of the structure.
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