Flexural and Shearing Capacities of Longitudinally Cracked and Retrofitted Wood Beams

Abstract:

Wood structural members are prone to endsplitting and cracking along the longitudinal axis, due to external loading and changes of humidity. Such cracks can impair the structural integrity and lead to stress concentration in the vicinity of the crack tips, thereby significantly reduce the load carrying capacity of the wood members. This paper presents the results of fullscale bending tests with longitudinally cracked wood beams. With consideration of the variation of specimen quality and the size effect of wood strength properties, the influence of crack length and position along the crosssectional height on the bending resistance of the wood beams was identified. The retrofitting effect of selftapping screws was also investigated considering different provisions and spacings. It was found that the longitudinal cracks within the shear span and at the midheight of the crosssection can lead to the biggest decrease (46.2%) of the bending resistance, and the selftapping screws are most efficient (retrofitting ratio of 1.12) while applied to the shear span and the retrofitting effect may decrease with the increasing of the screw spacing.