Concrete knots for timber construction
Table of contents
Project data
| Titel | Title Eingegossene Betonknoten-Verbindungen für hochbeanspruchte Stab- und Fachwerkkonstruktionen im Ingenieurholzbau | Moulded composites of concrete knots for highly stressed mullions structures and timber framework in timber engineering Förderer | Funding Arbeitsgemeinschaft industrieller Forschungsvereinigungen “Otto von Guericke“ e. V. (AiF) Zeitraum | Period 11.2009 – 08.2012 Leiter | Project Manager Prof. Dr.-Ing. Peer Haller Bearbeiter | Contributors Dr.-Ing. Jens Hartig, Dr.-Ing. Andreas Heiduschke, Dipl.-Ing. Robert Putzger Projektpartner | Project Partners Hess Timber GmbH & Co. KG |
Report in the yearbook 2012
Wooden trusses with concrete nodes
Test girder with 10 m span in the testing machine
The targeted use of different materials in so-called hybrid structures is attracting increasing attention in civil engineering research. One example of this is the wood-concrete composite construction method, for which a new aspect was investigated in this research project of the Chair of Timber Engineering and Structural Design of the Faculty of Civil Engineering.
The aim was to develop efficient connection details for timber trusses. The novel connection concept involves having the bars ending at the chords engage in recesses that are filled with grouted concrete. Compression bars are made of wood. Steel, on the other hand, is used for the tension bars, which are tied back in the concrete with anchor plates. The grouted node is thus subjected to a multi-axial compressive stress condition. The advantages of this concept include the accuracy of fit of the connections, which contributes to comparatively low deformations of the trusses, and the mainly fiber-parallel loading of the wood, so that unfavorable loads perpendicular to the fiber are avoided. Moreover, since no fasteners are externally visible, such trusses have a positive appearance.
The extensive experimental investigations for the research project were carried out in the Otto Mohr Laboratory. In addition to ultimate load tests on individual connections and truss systems, fatigue tests were also carried out under outdoor weathering over the period of more than one year. The highlight of the experimental program was the testing of a truss system with near-structural dimensions of 10 m span and 2 m height in the 10 MN column testing machine of the Otto Mohr Laboratory.