Lately there has been growing interest in the construction of tall timber buildings for promoting wood as a structural material and to contribute to the decarbonization of the built environment. One of the main challenges in such buildings is the high compressive loads acting in the joints, especially in the lower floors. In some cases, metal brackets are used to avoid loads perpendicular to the fibre direction. However, an alternative and more cost-efficient approach aims to eliminate metal components by relying on timber-to-timber contact between parallel wood fibres. The main drawback of such a solution is the potential crushing of end fibres, see Fig. 1(a). The topic of interaction between two surfaces with longitudinal fibre directions parallel to one another needs further research investigations at both the material and the structural scales. 

In this presentation, we address this topic by modelling fibre-fibre interaction at both micromechanical and structural scales, see Fig. 1(b). Numerical micromechanical models are powerful to understand material behaviour associated with damages [1]. The developed model is parametric and accounts for wood fibre geometry in earlywood and latewood as well as their differing mechanical properties. To validate the developed models, micromechanical tests have been conducted in miniature test rigs. In parallel, the topic is also addressed in the application perspective, providing a practical and effective tool for structural engineering analyses. Fig. 1 (b) shows the numerical structural scale model of fibre-fibre joints with a contact zone [2]. Such structural scale joints were experimentally tested in our laboratories. Results from numerical simulations and corresponding experimental investigations will be presented and their limitations and advantages will be discussed.