Abstract
Due to the strong demand for wood, and the need to reduce the carbon footprint in construction, fast-growing low-graded planted species like poplar are promising wood for the supply chain in the context of engineered wood products, EWPs. Finger joints constitute a key technology for the manufacture of long structural elements of EWPs. Thus, evaluation of the mechanical properties of finger joints is important when designing these structural members. This paper shows the results of mechanical behaviour in tension of poplar timber of the I-214 cultivar, for specimens with and without finger joints, using experiments monitored by DIC (Digital Image Correlation) and simulated by the Finite Element Method. For moderate and intermediate loads, the samples with finger joints showed behaviour similar to those without joints. However, the presence of the fingers decreased the mechanical properties of the modulus of elasticity in the longitudinal direction anywhere from 7.7 to 23.7%; and there was a decrease of around 27.5% in tensile strength. An agreeable correlation between the DIC results and FEM simulations is obtained for the longitudinal, transversal, and shear strain fields, thus demonstrating the high potential of both methodologies.
Highlights
IntroductionWood is a natural organic, anisotropic, and renewable material with excellent ecological properties, acting as a carbon sink and characterized by a low embodied energy
The adhesive for the finger joint was applied at a temperature of 20 ± 2 °C, with a wood moisture content (MC) of 9.8 ± 1.5%, complying with the requirements of the manufacturer for its application
For the TF specimens with an extensometer or area located at the finger joint, the relations are slightly lower due to the strain concentration captured by Digital Image Correlation technique (DIC) at the base of the fingers
Summary
Wood is a natural organic, anisotropic, and renewable material with excellent ecological properties, acting as a carbon sink and characterized by a low embodied energy. Timber is one of the most important materials used over centuries within the construction sector (Harte 2016). Because the timber market is continually increasing, the need for elements with special shapes and higher spans has become overwhelming. Complex connection—mechanically or adhesively bonded— is a common demand. Finger joints are currently used to produce engineered wood products like glued laminated timber beams (glulam) for different construction sectors, including buildings, bridges, or sport halls. A main benefit/advantage of implementing finger joints is the possibility to avoid certain types of flaws (e.g., grain deviation, knots, cracks, etc.) and geometrical imperfections
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