In timber construction, curved timber components have been used repeatedly. Yet the use of curved CLT elements is a relatively recent phenomenon. To obtain a European Technical Approval (ETA) for so-called radius timber (single curved CLT elements), Holzbau Unterrainer GmbH commissioned the accredited testing institution TVFA – Innsbruck to carry out the tests required for this purpose. To this end, overall 158 tests were performed in building component dimensions from December 2013 to May 2014, and several laboratory tests were carried out to monitor adhesive joint quality. Due to the single curved shape of radius timber elements, it is key to particularly focus on possible implications on load bearing capacity due to pre-stress of the slats and to the tensile stress perpendicular to grain resulting from deflection forces. To comply with the criteria laid down in the semi-probabilistic safety concept used in Eurocode 5, the impact caused by these pre-curvatures on strength, rigidity and gross density must be known.
During the last three decades there has been increasing concern within the scientific community about the effects of indoor air quality on health. Changes in building design devised to improve energy efficiency and has induced that modern homes and offices are frequently more airtight than older structures. Furthermore advances in construction technology have caused an extensive use of synthetic building materials. The construction process and the production of building materials not only consume the most energy they also have a big impact on the Global Warming Potential. While these improvements have led to more comfortable buildings with lower running costs, they also provide indoor environments in which contaminants are readily produced and may build up to much higher concentrations than outside. Because about 80-90% of our time is spent indoors, where we are exposed to chemical and biological contaminants and possibly carcinogens, the Indoor Environmental Quality plays an increasing role. The aim of this study was to develop building components out of sustainable natural materials for modular building concepts with regard to the Indoor Environmental Quality such as the air quality and the indoor climate, the temperature and humidity. To guarantee high Indoor Air Quality a mechanical ventilation system is part of the construction. It has to ensure a controlled air change with a minimum of dissipation of energy. Building parts were assembled to meet high energy efficiency Standards. For the construction parts wood, hemp, sheep wool and clay were used to meet the settled requirements. As a first result of this study two modular buildings were erected, in which the indoor air quality and the construction physics will be monitored in the next few years for generating valuable data.
The challenge with point-supported flat slabs is the stress concentration at the supporting points. The small strength of the wood perpendicular to the grain should not reduce the load carrying capacity of the CLT –Panels. Therefore, there are some existing state of the art methods of reinforcement with self-tapping screws, which open up the...
