In timber construction, curved timber components have been used repeatedly. Yet the use of curved CLT elements is a relatively recent phenomenon. To obtain a European Technical Approval (ETA) for so-called radius timber (single curved CLT elements), Holzbau Unterrainer GmbH commissioned the accredited testing institution TVFA...
This thesis presents a state of the art on moisture induced stresses in glulam,
complemented with own findings. These are covered in detail in the appended
papers. The first objective was to find a suitable model to describe moisture
induced stresses, in particular with respect to mechanosorption. A review of
existing models led to the conclusion that the selection of correct material
parameters is more critical to obtain reliable results than the formulation of the
mechanosorption model. A series of laboratory tests was thus performed in order
to determine the parameters required for the model and to experimentally
measure moisture induced stresses in glulam subjected to one dimensional
wetting/drying. Special attention was paid to using glulam from the same batch
for all the experimental measurements in order to calibrate the numerical model
reliably. The results of the experiments confirmed that moisture induced stresses are
larger during wetting than during drying, and that the tensile stresses could
clearly exceed the characteristic tensile strength perpendicular to grain.
A new approach to reinforce glulam timber beams has been developed by using compressed wood (CW) which is made of a lower grade wood through densification processes. In the reinforcing practice, compressed wood blocks are inserted into pre-cut holes on...