Holzforschung Austria

Vienna, Austria

Holzforschung Austria

Vienna, Austria
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Hackspiel C.,Holzforschung Austria | Schober P.,Holzforschung Austria
WCTE 2016 - World Conference on Timber Engineering | Year: 2016

The architectural need for more transparent building envelopes not only changed the appearance of the buildings, but also their structural behaviour. Walls do not only have a vertical load-bearing function any more, they are also used for the transfer of wind and earthquake induced loads. Structural sealant glazing structures have been used for a long time and are nowadays state of the art technology. In these applications, however, the glass has not got a load bearing function. It only serves as a pure building envelope. Research projects carried out at Holzforschung Austria over more than ten years have shown that timber-glass composites can be used as load-bearing elements in wooden frame houses. A construction system was developed, which allows for a very cost-efficient use of prefabricated timberglass-composite elements on building site. The principle suitability of several adhesives considering different loadings was investigated by means of small scale experiments. Thereafter, the load bearing capacity of such elements was investigated by means of large-scale fracture tests of prototypes providing insight into the load transfer and failure mechanisms. Long-term aspects such as the durability and the robustness of the composite elements were also investigated, as well as questions regarding building physics. The conclusions gained from these research activities were also applied in timber-glass-composite prototypes which have been installed in real buildings. They allowed for a long-term monitoring of such composite structures. A research project at the Vienna University of Technology, Department Structural Design and Timber Engineering, which was finished in 2015, has led to a comprehensive design concept, which allows for an analysis and design of timber-glass-composite constructions. It is based on the combination of spring models and deals with the incorporation of the shear wall- and the compression diagonal-theory in the glass. Numerous applications of the timber-glass-composite system developed by Holzforschung Austria in real buildings, from single-family houses to large facades, have proved the advantages of this system.

Plossnig-Weigel B.,Holzforschung Austria | Polleres S.,Holzforschung Austria
WCTE 2016 - World Conference on Timber Engineering | Year: 2016

Dataholz.com is a web-based tool for planning and assessing timber-based buildings and providing support and help to the user on technical issues and building physics. The tool provides information for planners of timber buildings from early design decisions to finding the optimal solution for construction, building physics and behaviour concerning energy demand of timber constructions. The main asset of dataholz.com is a catalogue of reviewed timber building components such as walls, floors and roofs, where thermal, acoustic, fire performance and ecological parameters are stated. All these specified performance levels were determined either by testing, calculation or by means of an assessment done by accredited testing institutes. The information is provided in terms of downloadable and printable PDF files and is accepted for submission to building authorities as a confirmation of compliance. dataholz.com is a unique comprehensive database of timber knowledge with acceptance by authorities in Europe.

Forsthuber B.,Holzforschung Austria | Schaller C.,BASF | Grull G.,Holzforschung Austria
Wood Science and Technology | Year: 2013

A study of the surface discolouration of clear coated wood during artificial and outdoor weathering and its prevention using clear coatings comprising organic UV absorbers (UVA) and mineral UV screeners was carried out. It was shown that the use of UVA and UV screeners in clear coatings was very effective in reducing photodegradation of the wood surface. Preliminary irradiation trials with Xenon arc light showed that the UV screener TiO 2 led to the least discolouration of the coated wood surface, closely followed by UVA of the hydroxyphenyl-s-triazine class (HPT). The artificial and outdoor weathering trials indicated that UVA of the HPT class stabilised the colour of the wood surface better than UVA of the 2-(2-hydroxyphenyl)- benzotriazole class (BTZ). Comparison of different artificial weathering methods indicated that Xenon arc light weathering showed the best match to the proceeding discolouration of the clear coated wood panels during outdoor weathering. © 2012 Springer-Verlag.

Forsthuber B.,Holzforschung Austria | Muller U.,Wood us Competence Center for Wood Composites and Wood Chemistry | Teischinger A.,University of Natural Resources and Life Sciences, Vienna | Grull G.,Holzforschung Austria
Polymer Degradation and Stability | Year: 2013

In this study, we hypothesized that the use of UV absorber of the hydroxy-benzotriazole class (BTZ) and micronized TiO2 (NTiO 2) as mineral UV screener could stabilize the chemical and mechanical properties of clear wood coatings based on a high Tg/low T g multiphase acrylic binder dispersion. The photooxidation rates were compared using ATR-FTIR techniques and tension tests. For qualitative and quantitative chemical analysis and correlation to the mechanical properties, multiple linear regression (MLR) was used, which was a suitable method to monitor the chemical changes of the polymeric binder and to investigate the influence of these light stabilizing additives on the photooxidation behavior. The analysis of mechanical properties of the acrylic binder during exposure to Xenon arc light showed that both BTZ and NTiO2 stabilized the Young's Modulus and the elongation at break during the whole cycle. BTZ showed better results. However, it led to a strong decrease of the initial Young's Modulus whereas NTiO2 showed no comparable effect. We concluded that BTZ was very efficient in reducing the photooxidation and the accompanied change of the elastic properties of the acrylic binder. NTiO2 only stabilized the high Tg component of the multiphase acrylic binder whereas the photooxidation of the low Tg component was accelerated. This may be explained by a photocatalytical activity of NTiO2. © 2013 Elsevier Ltd. All rights reserved.

Stefko J.,Technical University In Zvolen | Bednar J.,Holzforschung Austria
Key Engineering Materials | Year: 2016

The paper deals with laboratory air tightness testing of wood based construction materials with the focus on the proportion of air infiltration through the building envelope in the air exchange of the building. Results of the specific materials testing - cross laminated timber (CLT), OSB and other structural materials are analysed in the paper. Moreover, the effect of production technology, material, its thickness and surface treatment are studied. Results of laboratory testing provide valuable data for detailed computer modelling of air exchange through the infiltration, especially in vapour diffusion-open elements of building envelope. © 2016 Trans Tech Publications, Switzerland.

Dolezal F.,Holzforschung Austria | Spitzbart-Glasl C.,Holzforschung Austria
Energy Procedia | Year: 2015

Several initiatives have been launched to increase sustainability in building industry. All of them contain a shift in focus from energy consumption to a wide variety of indicators for the full life cycle. This implies a broader view, not only based on the ecological, but on the economic and social performance of buildings as well. A closer look on internationally acting Green Building Labels reveals that acoustic performance and noise protection is seen as an important part of the social sustainability aspects of a building. Thus, the approach of how to consider the acoustic performance and impact on rating results vary heavily. © 2015 The Authors.

Weidenhiller A.,Holzforschung Austria | Denzler J.K.,Holzforschung Austria
Computers and Electronics in Agriculture | Year: 2014

This paper deals with pattern recognition based on colour and texture. The aim is to detect areas of bark and wood on images of spruce logs taken in the industrial environment of a sawmill. Bark is a material with high natural variability in texture and colour even in a single tree species such as spruce and is a challenging subject for pattern recognition. The study compares three algorithms based on colour, texture and an integrated combination of colour and texture, respectively. Relevant sources of variation between and within logs are identified: colour variations on bark and wood, dirt, and traces of the bark beetle. Modifications of the algorithms with the potential to further improve the bark detection performance are discussed. © 2014 Elsevier B.V.

Sikkema R.,University Utrecht | Junginger M.,University Utrecht | Pichler W.,Holzforschung Austria | Hayes S.,National Energy Foundation NEF | Faaij A.P.C.,University Utrecht
Biofuels, Bioproducts and Biorefining | Year: 2010

The European wood pellet market is booming: concerns about climate change and renewable energy targets are predominant drivers. The aim of this analysis is to compare typical wood pellet chains from the purchase of the feedstock from sawmills to the conversion into heat or electricity. Cost structures, primary energy inputs and avoided greenhouse gas (GHG) emissions are reviewed. Three cases are defined: pellets for district heating (DH) in Sweden (replacing heavy fuel oil); bagged pellets for residential heating in Italy (natural gas); and Canadian pellets for electricity production in the Netherlands (coal). Supply may cost €110-€170 per tonne of delivered pellets, with the main cost factors being feedstock collection, drying and long-distance ocean transportation (for Canadian pellets only). Largest avoided emissions are for power production (1937 kg CO2eq/tonne of pellets), followed by district heating (1483 kg). In relative terms, the GHG reduction varies from 81% for residential heating (with pre-dried feedstock) to 97% for DH. Based on a wood-pellet consumption of 8.2 million tonnes, the EU27 plus Norway and Switzerland avoided about 12.6 million tonnes of CO2 emissions in 2008. Concluding, wood pellets can achieve substantial GHG savings, especially when substituting coal for power production. However, wood pellets are relatively expensive, especially compared to coal. Only in the case of high oil prices, can the substitution of heating oil for DH be commercially viable. In most other cases, substitution is only possible with financial support from national governments, for example, feed-in tariffs or carbon taxes. The commercial markets for CO2 emission rights may cover some costs, but their impact is still limited. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd.

Denzler J.K.,Holzforschung Austria | Weidenhiller A.,Holzforschung Austria | Golser M.,Holzforschung Austria
Scandinavian Journal of Forest Research | Year: 2015

This paper summarises the comparison between log properties and resulting structural timber properties. The establishment of these relationships is a first step to place the grading as early as possible in the production process, if possible directly on the log. To find out what should be detected on the log, the modulus of elasticity (MOE) based on longitudinal frequency, the number of resin pockets and the value for spiral grain were detected. Relationships are established to the corresponding properties on the structural timber produced out of it and to visual log grades commonly used in Austria. This paper discusses advantages and disadvantages of these properties on 85 spruce logs. The MOE based on longitudinal frequency showed high potential whereas the number of resin pockets and the value of spiral grain only helped to identify timber unsuitable for construction. © 2015 Taylor & Francis.

Forsthuber B.,Holzforschung Austria | Grull G.,Holzforschung Austria
Polymer Degradation and Stability | Year: 2010

A study of the photocatalytic degradation of an acrylic dispersion based coating and its prevention using hindered amine light stabilizers (HALS) was carried out on solid films by exposing them to Xenon arc light. The degradation rates were compared using FTIR-ATR techniques by plotting the differential build up of the hydroxyl and hydroperoxide bands as function of exposure time. UV-Vis spectroscopic studies were carried out as well to obtain data about the light stabilization of organic UV Absorbers (UVA) and inorganic UV screeners by HALS. The effectiveness of an aqueous primer comprising a specific lignin stabilizing HALS in combination with clear topcoats with UVA or UV screeners in the prevention of photo-induced discolouration of wooden surfaces was investigated by measuring the colour change during exposure time. It was shown, that the usage of HALS was effective in reducing the degradation speed of clear coats with UVA and UV screeners. Results obtained by UV-Vis spectroscopic analysis during the exposure cycle showed an inhibition of the photo-degradation of the UVA themselves, while no positive effect occurred on inorganic UV screeners. A lignin stabilizer containing aqueous primer with a specific HALS as active component, showed some promising results in combination with transparent topcoats comprising organic UVA and inorganic UV screeners, except ZnO, where a strong antagonistic effect occurred. © 2010 Elsevier Ltd. All rights reserved.

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