Structural potential of curved and bifurcated misfit wood logs

Abstract

This study examined the structural potential of misfit wood–wood that does not meet the quality or measurement criteria for saw logs due to the curved or bifurcated shape–sourced from continuous forest harvesting. These logs are top segments of felled trees characterized by diverse morphologies with bottom diameters ranging from 96 mm to 187 mm. A total of twenty sizable logs, each measuring between 2,400 and 2,505 mm in length, were tested, including specimens from both Scots pine and silver birch species. Despite variations in shape and thickness, the tests revealed similar behavioural patterns: pronounced nonlinear load-deformation behaviour, and fibre buckling in compression and tensile failure roughly at midspan. The bifurcated specimens experienced fractures at the upper, thicker section of the bifurcation. Comparative calculations with a simplified analytical model, considering curvatures and diameters, demonstrated conservative results. This study has shown that the structural load-bearing capacity of curved and bifurcated round wood can be estimated using the current calculation methods.