The long-term deformation behavior of timber-steel hybrid beams was analyzed and tested in specific long-term tests presented at WCTE 2016. The documented reduction of their creeping values in approximately 50% indicates that also some kind of improvement can be expected in the further development of prefabricated timber-steel-concrete ribbed decks. In order to confirm this hypothesis a long-term creeping test under permanent load was designed,aiming to compare the deformation behavior of beams with a timber-steel-concrete and a timber-concrete cross-section.The tests will be performed on down scaled beams of 4 m instead of 6 m span due to a restricted capacity of load implementation and space limitations in the testing laboratory . The creeping beams were designed to have the same stress levels as the real ones in order to ensure the comparability of the results with the actual scope of application.
The timber industry has experienced in the last decades a relevant increase in terms of high performance buildings. Despite these advancements and the favorable properties of building with wood, the traditional position of "choosing by costs" still finds wooden building as more expensive than concrete or steel ones. In order to be competitive in the market against these two main building materials and meet the expectations of modern and large-volume wood based constructions, new improvements based on standardization and prefabricated systems have to be implemented. At the same time a full collaborative work between all the participants on a project is needed to redefine and optimize the construction and design processes through sharing specific and detailed information and extended know-how at a very early project stage. Through this approach, the high potential of combining off-site construction, Building Information Modeling (BIM) as a work methodology and lean management practices will be investigated, involving architects, engineers, BIM users in the timber industry, timber manufactures, contractors and all the stakeholders with the aim of reaching the most effective and productive design and construction process in multi-story timber buildings.
Timber-steel hybrid elements are structurally reliable, clean and fast to assemble and disassemble, light, ecologic and economic. Design criteria and a calculation model for beams were developed and a series of real scale tests were carried out in order to check their performance. The results proved to be satisfactory and promising for the final objective of building structural frames for different types of multi-story buildings.
Timber-steel hybrid beams have been proposed, tested and analyzed for their use in multi-storey buildings. After the first concepts and tests were presented in the WCTE 2014, two whole testing series are finished and their results globally presented and analyzed. The beams fulfilled all the expectations and therefore can be presented as a reliable possibility for future proposals of timber-based frame multi-storey buildings. The present paper presents a summary of the part regarding hybrid beams inside the research project “Timber based mixed systems for dense construction in urban areas” carried out by the Institute of Structural Design and Timber Engineering of the Vienna University of Technology.
