| 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. |
- Buck, Dietrich, et al.
(författare)
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Further Development of Cross-Laminated Timber (CLT) : Mechanical Tests on 45° Alternating Layers
- 2016
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Ingår i: WCTE 2016 : Proceedings. - Vienna : Vienna University of Technology, Austria. - 9783903039001 ; , s. 1107-1114
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Konferensbidrag (refereegranskat)abstract
- In this paper, a series of experimental bending and compression tests were performed on cross-laminated timber (CLT) products with ±45° alternating layers, to evaluate their performance against conventional panels of 90° orientation. Engineered wood products, such as CLT with ±45° alternating layers can provide opportunities for greater use in larger and more sustainable timber constructions. A total of 40 panels, manufactured in an industrial CLT production line with either of these two configurations, were tested and compared. Panels were evaluated in bending tests n=20 and the remaining ones in compression tests. Results showed that 35% increased the strength in the four-point bending tests for panels containing ±45° alternating layers compared with the 90° alternating layers. Compression strength was increased by 15%. Stiffness increased by 15% in the four-point bending and 30% in the compression. The results indicate that CLT containing ±45° alternating layers has increased strength and stiffness compared to 90° alternating layers. These findings suggest that further developments in CLT are feasible in advanced building applications.
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| 3. |
- Olsson, Jörgen, 1975-, et al.
(författare)
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Low Frequency Force to Sound Pressure Transfer Function Measurements Using a Modified Tapping Machine on a Light Weight Wooden Joinst Floor
- 2016
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Ingår i: Proceedings of WCTE, World Conference on timber Engineering, August 22-25, 2016, Vienna, Austria. - Vienna : Vienna University of Technology. - 9783903039001 ; , s. 2888-2895
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In recent years research has shown that low frequency impact sound is of significant importance for inhabitants´ perception of impact sound in buildings with light weight wooden joist floors. The tapping machine is well defined as an excitation device and is a standard tool for building acoustics. However, the excitation force spectrum generated for each individual floor is unknown when using a tapping machine. In order to increase the possibilities to compare simulations to impact sound measurements, there is a need for improvement of impact sound measurement methods. By measuring the input force spectrum by a modified tapping machine and the sound in the receiver room, transfer functions can be achieved.In the light weight wooden building used for the evaluation test of the proposed method, structural nonlinearities are evident in the frequency response functions stemming from different excitation levels. This implies that for accurate FRF-measurements in low frequencies, excitation magnitudes that are similar to these stemming from human excitations should preferably be used.
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| 4. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Load Distribution in Multi-Dowel Timber Connections under Moment Loading : Integrative Evaluation of Multiscale Experiments
- 2016
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Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- The load distribution in multi-dowel timber connections under bending moments was investigated by means of an integrative evaluation of a hierarchically organized test program, which encompassed component tests as well as single dowel and multi-dowel connection tests. It was demonstrated that the anisotropic material behaviour of LVL, and consequently of wood in general, leads to a non-uniform distribution among the dowels.
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| 5. |
- Bard, Delphine, et al.
(författare)
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Silent Timber Build - Development of low frequency vibroacoustic prediction tools for lightweight wooden constructions
- 2016
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Ingår i: WCTE 2016 - World Conference on Timber Engineering. - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- The goal of the Silent Timber Build project is to develop new prediction tools for timber structures. As a matter of fact, impact sound insulation in the low frequency range is a crucial point concerning satisfaction of lightweight wooden-based building residents. Floor systems are rather complex: multi-layered, multi-cavity, stiffened, with floor covering and ceiling (either rigidly connected, suspended, or completely independent), etc. Finite element (FE) simulations have proved to be useful in the design phase for the low frequency range (below 200 Hz). To address mid and high frequency range, other methods have to be implemented such as Statistical Energy Analysis (SEA). This paper concentrates on impact sound insulation prediction in the low frequency range by means of FE simulations and presents first validation steps for a wooden floor identified as representative in Europe. The main difficulties in impact sound insulation prediction are identified and discussed.
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| 6. |
- Briggert, Andreas, 1984-, et al.
(författare)
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Evaluation of three dimensional fibre orientation in Norway spruce using a laboratory laser scanner
- 2016
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Ingår i: WCTE 2016. - Vienna : Vienna University of Technology. - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- This paper addresses laser scanning and utilization of the tracheid effect for determination of local fibre orientation, which is decisive for strength and stiffness of timber. A newly developed laboratory laser scanner that can be used for high resolution and high precision scanning of wood surfaces is used for in-depth assessment of a single Norway spruce specimen that contains a knot. It is assumed that the specimen has a plane of symmetry, through the knot, and by splitting the specimen in two parts it is possible to determine fibre orientation on orthogonal planes. Hence, by relying on the assumption of symmetry, the fibre orientation in 3D space can also be determined. The results are used to evaluate the possibility of utilizing the tracheid effect for determination of the out-of-plane fibre angle of an investigated surface. Furthermore, the results are used for verification of a theoretical fibre orientation model that has often been used by researchers.
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| 7. |
- Dorn, Michael, 1978-, et al.
(författare)
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Non-Linear Connection Models in Timber Engineering
- 2016
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Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- In this contribution, a numerical model for connections in engineered timber structures, using specially designed connection elements, is presented. The model considers the non-linear load-displacement relation typical for many types of connections on different levels and is presented on the example of dowel-type connections. The structural levels investigated herein are a) the embedment behaviour of a dowel into wood; b) the behaviour of a singledowel connection; and c) a multi-dowel connection under a general load case typical for structural applications. A special characteristic considered in the formulation of the connector elements is the unloading behaviour, which is characterized by an initial high unloading stiffness but a very low stiffness when the load is fully removed. The latter is due to remaining permanent deformations in the wood as well as in the metal connector. The modelling approach was found to correlate well with experimental data and gave new insight in the behaviour of dowel connections, particularly as regards the unloading and reloading behaviour with alternating load directions on the single-dowel connection scale.
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| 8. |
- Fortino, Stefania, et al.
(författare)
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A multi-Fickian hygro-thermal model for timber bridge elements under Northern Europe climates
- 2016
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Ingår i: WCTE 2016. - 9783903024359 ; , s. 2068-2075
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Konferensbidrag (refereegranskat)abstract
- This work proposes a multi-Fickian method to analyse the hygro-thermal behaviour of timber bridge elements under Northern Europe climates. A temperature-dependent wood hysteresis is included in the model and the thermal effects due to temperatures above and below zero are taken into account. As a case study, the model is used for the hygro-thermal simulation of a glulam beam of Älsvbacka bridge in North of Sweden that was monitored by using wireless sensors in a previous study. The model, implemented in Abaqus FEM code, is able to predict the states of moisture and temperature in protected parts of the beam by using as external loads the relative humidity and temperature of the air provided by in-situ measurements. Furthermore a simplified model using a wood hysteresis independent of temperature is found to provide similar results and appears easier to implement in finite element codes.
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| 9. |
- Goto, Yutaka, 1984, et al.
(författare)
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Hygrothermal Design of a Prefabricated Wooden Facade Module for School Building Renovation in Sweden
- 2016
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Ingår i: World Conference on Timber Engineering (WCTE 2016), August 22-25, Vienna (Austria). - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- Today it is widely recognized that the construction industry plays a key role in the rational use of resources and the realization of a more sustainable society. Concerning buildings and energy use, renovation of the existing building stock to the higher energy performance is crucial. Among the various existing buildings in Europe, school buildings are of importance among the publicly owned buildings. However, there has been little effort in Sweden to promote the school building renovation by prefabricated wooden modules, which should be highly advantageous due to the short refurbishment period and its light weight.The present study investigated the hygrothermal property of wooden refurbishment modules in combination with an existing brick wall under Gothernburg (Sweden) climate. The criterion for the moisture safety inside the wall after the refurbishment was at 75% relative humidity in order to comply with the Swedish building regulation while it was assumed that the surface of the wall was wet from the precipitation during the refurbishment period. Two-dimensional transient heat and moisture transfer simulation was applied to three different module configurations. It was shown it is important to design the module vapour permeable so the entire wall system after the refurbishment have sufficient drying potential.
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| 10. |
- Hochreiner, Georg, et al.
(författare)
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Matrix Failure of Multi-Dowel Type Connections Engineering Modelling and Parameter Study
- 2016
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Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
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Konferensbidrag (refereegranskat)abstract
- A simplified numerical engineering model for the design of the surrounding timber matrix of dowel groups, developed within the framework of a commercial structural analysis software, is presented herein. This model was applied to highlight and reflect various dowel arrangements in timber to steel connections from building practice subjected to arbitrary sets of internal forces against the background of both the real mechanical behavior and the present practice of design. A parameter study revealed the interdependence of stresses in the timber matrix and geometrical and mechanical properties of dowel groups.
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