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

我们的社会对人类干预自然和环境的影响越来越敏感，这促使人们研究以自然为基础的产品，从而增加了木材在建筑中的使用。传统上基于预制半成品的木结构建筑是用简单的几何形状和适应性强的基本形状建造的。预制技术，如胶合板木材允许均匀化，实现通用的机械特征。然而，制造板、杆和梁中的木制建筑元件与相当大的物流工作相关，其中仅使用干木材，导致大量的铣削废料。分支木被完全处理掉。因此，传统的木结构建筑和主要采用线性元件的建筑系统针对通用应用和正交几何形状的建筑构件的构造进行了优化。然而，它们对于原木材的经济利用不是最佳的。 基于替代木材结构系统的发展，例如“无结结构”，也可以使用自然生长的木材元素进行微小的调整。 为此，先进的数字方法，如基于图像的建模和形态分析和分类，可以从单个自然生长的木质部件及其相应的部分生成新结构的几何形状。先进的非线性模拟技术和数值建模，如等几何分析，考虑层的极性排列，沿半径沿着具有可变强度特性的不同密度，代表具有木材典型各向异性行为的纤维状材料的配置。基于这个分析工具的合成方法将被开发，以模拟树的生长的影响，简单的引力取向或一般的强制力。为此，必须推导出木材在活体和变性（干燥）状态下的材料特性以及影响机械特性的生物学变化。最相关的生物影响因素，如纤维组织的发展和密度必须被识别和传输到模拟参数。该项目旨在以创新的方法系统地使用自然生长的木材，并加深对树木生长的了解。

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.