Experiments and modelling of the load capacity of green wood

Abstract

The material properties of green wood in the shaft of vital trees differ significantly from the generally known material properties of technically processed, dried wood. Furthermore, completely different residual stresses and fracture mechanisms are present in the natural full cross-section [1]. The properties also depend on the tree species. Our work focuses on green wood from european beech (Fagus sylvatica). A large number of experiments on small test specimens of green wood are known from [2]. We present both, experiments on small and large-scaled specimens. Latter are bending test on trunks with full cross-section. Combining results and considering micro-mechanical properties of cellular wood components [3], a computational model is fitted to our experimental results. This aspect influences the fracture resistance of a tree and should be representable in a computational model. This is particularly important in order to better assess the risk of building on vital trees.