Formholzrohre - Stand der Forschung und Anwendungen

Moulded wooden tubes - State of research and potential for application

This contribution gives an overview of the state of research on circular moulded wooden tubes with optional fibre reinforcement. Moulded wooden tubes are produced by forming of panels, which were densified previously to about one half of the initial volume transverse to grain. The resulting hollow sections have higher load-bearing capacities compared to solid sections of the same material volume due to the larger moments of inertia. This paper shows results of experimental investigations regarding the load-bearing behaviour of wooden tubes under compression, bending and torsion as well as the durability. Fibre reinforcements of glass or carbon and epoxy resin on the outer surface of the tubes increase the load-bearing capacities, the ductility and the durability. Moreover, ecological aspects of wooden tubes compared to steel and steel-reinforced concrete are pointed out. Finally, possible applications are addressed. A prototype of a wind energy plant with a shaft of wooden tubes is briefly presented.