P_2.1.4 multi_girder

Based on the existing know-how as well as the failure probability and reliability of tensile-tested sawn timber, the timber shall then be built up to rod-like timber products, such as glulam, or DUO- / TRIO beams. The idea is to single out the differences between “proof loading” tested and non-tested timber, and to show the advantages regarding the mechanical properties, failure probability, reliability and design of these products.

In addition to this, the project shall help in developing and building up a beam-joining technique which is made from DUO and TRIO beams, respectively, that are put in layers over bonding. This product represents a novelty development in the timber trade and can, similar to glulam, be built up in a homogenous or combined manner. Starting from the knowledge gained so far, in the context of this project, the mechanical potential of strength and stiffness of this product together with the so-called volume effects which in their turn mostly influence the rigidity of structures shall be examined. Through the gluing of individual components, a homogenisation or reduction, respectively, of the diffusion in the final product can be brought about, and this can be accounted for via a system factor k_sys as far as the design is concerned. This system factor shall be determined by means of experimental examinations, models and simulation.

Furthermore, the finger-joint connection between the strength-graded squared lumber is to be examined in this project with regard to the differences and potentials between horizontal and vertical finger-joint connections with regard to their strength behaviour. In addition, the test program will not only be limited to spruce, but will also be extended to larch.