Economic dimensioning of wooden structures through efficient steel-timber dowel connections

Forming joints with high-performance and easy-to-create connections is the key to the economic optimization of timber structures. The efficiency of the joints includes, in addition to a high load-bearing capacity, also a high rigidity and optionally a high ductility. While the load-bearing capacity is already covered correctly by the standard, the determination of the connection stiffness is not satisfactory, although the determination of the connection stiffness, for example for moment resisting column bases, is common in timber construction. In addition to a redistribution of internal forces in the system, with an accurate prediction of the load-displacement behaviour, e.g. with the component method, also the expected failure mechanism of the connection can be predicted.

The aim of the research project is to achieve a more economical design of timber structures through the development of efficient steel-timber dowel connections. The load-deformation behaviour of steel-timber dowel connections plays a crucial role. The influence of important parameters that have not yet previously been considered should be investigated and quantified as accurately as possible. Among other things, the effects of a change of the number of dowels in the grain direction, of the load-to-grain angle or of the slenderness of the fastener or the influence of reinforcing measures on the stiffness have to be examined.

In order to systematically investigate the influence of various parameters on the stiffness of steel-timber dowel connections, over 140 experimental tests will be carried out at the Materials Testing Institute of the University of Stuttgart (MPA) as part of the research project. The various connections were selected in such a way that the widest possible database is created and a statement can be made about the influence of the investigated boundary conditions.

By combining experimental investigations, an analytical prediction and numerical investigations, the topic of rigidity of steel-timber dowel connections should be examined as closely as possible. For the analytical prediction of the expected stiffness, on the one hand an approach based on an extension of the theory according to Johansen, on the other hand an approach similar to the effective number for the load bearing capacity of dowel-type fasteners should be developed. For the designer the aim is to take as many influencing parameters on the stiffness as possible into account, but still using calculation methods following the typical, well-known procedures.

Universität Stuttgart
Institut für Konstruktion
Prof. Dr.-Ing. Ulrike Kuhlmann

Hochschule Biberach
Institut für Holzbau
Prof. Dr.-Ing. habil. Jörg Schänzlin

• Internationaler Verein für technische Holzfragen (iVTH)
• AiF IGF; Schaffitzel Holzindustrie GmbH; WIEHAG GmbH
• SPAX International GmbH & Co. KG
• Pollmeier Massivholz GmbH & Co. KG

01.03.2019 - 30.06.2021