Abstract
Various design codes and design proposals have been proposed for glued laminated timber beams with round holes, assuming that the entire beam is composed of homogeneous-grade timber. However, in Japan, glued laminated timber composed of homogeneous-grade timber is rarely used for beams. In this study, the difference in the load-bearing capacity of glued laminated beams composed of homogeneous-grade timber and heterogeneous-grade timber with round holes when fractured by cracking was investigated experimentally and analytically. The materials used in the tests were glued laminated beams composed of homogeneous-grade Scots pine timber with a strength grade of E105-F345 and heterogeneous-grade Scots pine timber with a strength grade of E105-F300. Experiments confirmed that although the glued laminated beams composed of heterogeneous-grade timber have a lower material strength in the lamina with holes, its resistance to fracturing due to cracks associated with the holes is almost the same as that of the glued laminated beams composed of homogeneous-grade timber. The stresses acting on the holes in the laminated timber with holes of less than half the beam height were lower in the glued laminated beams composed of heterogeneous-grade timber than in the glued laminated beams composed of homogeneous-grade timber. The ratio of the stresses was found to be approximately equal to the ratio of the maximum bending stress or the maximum shear stress acting on the inner layer lamina, as determined by Bernoulli–Euler theory.
Highlights
When the shear force and bending moment act on a glued laminated timber beam with a round hole, the beam will undergo flexural fracture if the ratio of the bending moment is high
We examined the reduction rate of stress acting on the holes in the case of glued laminated beams composed of heterogeneous-grade timber, which is specified in Japanese Agricultural Standard (JAS) [7]
A new study conducted on glued laminated timber beams composed of homogeneous-grade to determine the difference in structural performance between homogeneous-grade and heterogeneous-grade glued laminated timber beams with round holes in comparison with the results reported previously is presented
Summary
When the shear force and bending moment act on a glued laminated timber beam with a round hole, the beam will undergo flexural fracture if the ratio of the bending moment is high. If the rate of shear forces acting on the beam is high, it will fracture through the development of cracks associated with the holes [1]. A large tensile stress perpendicular to the grain acts on the crack plane of the hole in the beam affected by the shear force or bending moment, and the tensile stress decreases exponentially with distance from the hole [2]. Various design codes and design proposals for glued laminated timber beams with round holes have been presented [1–6]. The design proposal of Aicher [2], 2] incorporates the size effect
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
