The strength behavior of wood in experiment and simulations Steffen FRANKE Research Assistant Bauhaus-University of Weimar Weimar, Germany Bettina FRANKE Research Assistant Bauhaus-University of Weimar Weimar, Germany Kay-Uwe SCHOBER Research Assistant Bauhaus-University of Weimar Weimar, Germany Karl RAUTENSTRAUCH Professor for Timber and Masonry Engineering Bauhaus-University of Weimar Weimar, Germany Summary The paper presents results of recent tests under compression, transverse tension and mixed mode stresses, based on a developed photogrammetric measuring procedure presented in [1]. The determined displacements of the measuring areas are easily transferable to a numeric simulation by a FE-Program. The strain dependent strength behavior, softening and hardening of wood transverse to the grain at loading areas with full area stress could be investigated by compression tests. These results were used to verify the simulation results, where different material models are available. Depending on the stress, the simulation model allows a more or less agreement to the experimental results. The 3-dimensional elastic-plastic material law from Grosse [2] could be applied for the simulation with good agreement. These numerical results provide interesting possibilities and they are most useful for the estimation of the load bearing behavior of wood in complex connections. 1. Introduction In the past years timber engineering has tried to evaluate the load-bearing capacity of structural members in areas of connections with mechanical connectors, openings and notches by fracture mechanics methods (FM). The assumption of FM parameters leads to problems in evaluating the load-bearing safety of structural units of full and board laminated timber in loaded areas and disturbance ranges using FM. Parameters close to reality can be gained only from experimental investigations by the determination of the crack expansion and the crack length with a subsequent FE-simulation. For application of timber construction, numerous theoretical and experimental investigations, which include joints, notches and openings stressed by transverse tension and tests stressed by different compression, have been reported in ref. [1]. Using the photogrammetric measuring the strain dependent strength behavior and FM parameters could be determined, ref.[3], [4], [5]. As a precondition for separate simulations of the ductile failure stressed by compression and the brittle failure stressed by tension using a cohesive zone material for delamination. Primary in ANSYS ® available material models don’t allow softening at least under compression stress. The material model ANISO is the only one with the possibility to account the 9 different strength values with corresponding MOE and through the bilinear law a linear hardening, but it isn’t possible to get a softening. This is for compression stress possibly acceptable but not for tension or shear stress. In contrast to this a 3-D elastic-plastic material law developed by GROSSE [2] was used to simulate the strength behavior realistically. It includes softening for tension, compression and shear and the hardening of wood under compression stresses.