Naturally grown timber elements as basis for load-bearing building structures - structural analysis and growth simulation

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The increasing sensitivity of our society to the effects of human intervention in nature and the environment is spurring research into nature-based products, leading to increased use of wood in construction. Timber constructions, traditionally based on prefabricated semi-finished products, are built with geometrical simple and adaptable basic shapes. Prefabrication techniques such as glue-laminated timber allow for homogenization achieving universal mechanical features. However, the manufacturing of wooden construction elements in boards, bars, and beams is associated with a considerable logistical effort, in which only stem wood is used, resulting in a big amount of milling waste. Branch wood is completely disposed of. So traditional timber construction and construction systems with mainly linear elements are optimized for an universal application and for the construction of building components of orthogonal geometry. However, they are not optimized for the economical utilization of raw wood material. Based on the development of alternative timber construction systems like e.g. 'Off-Knot-Construction,' also naturally grown timber elements with minor adaptations can be used. For that, advanced digital methods like image-based modeling and morphological analysis and classification allow to generate the geometry of new structures from individual, naturally grown wooden components as well as their corresponding sections. Advanced nonlinear simulation techniques and numerical modeling like e.g. isogeometric analysis consider a polar arrangement of layers, different densities along the radius with variable strength characteristics, representing the configuration of a fiber-like material with the typical anisotropic behavior of wood. Based on this analytical tool a synthetic approach will be developed in order to simulate the growth of a tree influenced by the simple gravitation tropism or by the imposition of forces in general. For this purpose, material properties in live and denatured (dry) state of wood as well as the biological alterations affecting the mechanical properties have to be derived. The most relevant biological influencing factors, such as fiber tissue development and density have to be identified and transmitted to simulation parameters. The project is aiming on an innovative approach to a systematic use of naturally grown wood as well as a deeper understanding of the growth of trees.