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.
Installing between-joist bracing can be an economical and effective means of mitigating excessive vibration levels in wood floors associated to human discomfort. Effectiveness of between-joist bracing depends upon its own rigidity that accounts for the location of bracing, geometric arrangement and connection stiffness of installed bracing elements to joist. This paper presents a method to quantify the flexural rigidities of between-joist bracing and their influence on vibrational serviceability parameters such as static deflection under a concentrated load and fundamental natural frequency of timber floor. A designer-usable analytical model, based on ribbed-plate theory, was used to predict static deflection and fundamental natural frequency by taking account of measured bracing rigidities. Results show that predictions the static deflection and natural frequencies. The proposed method and ribbed-plate model could be integrated into current design approaches to predict vibrational performance of timber floors.
Conventionally, energy absorption of joints in wooden structure has been obtained by yield deformation of steel parts. However, we have tried to control behaviour such as rigidity type or ductility type with combinations of wood fibre direction using screws in wooden structure for joint design. We defined the combination ratio of wood fiber as Rp (Ratio of parallel). First, we used special large diameter bolts to get high rigidity and ductility with embedding into combinations of parallel and orthogonal fiber directions. Then, we used long-screw which are more common in the market. We made all CLT test pieces by ourselves. We have compared the joint behavior with experiments and analysis. As a conclusion, we got following results of this study. When Rp rises, rigidity will be higher. On the other hand, ductility will be higher when Rp falls. We suggest the relationship equation for Rp and the rigidity and ductility of the increase or decrease by the theoretical value.
