Tensile Performance of Traditional and Modern Corner Joints in Wooden Structures

Corner joints are critical points of wooden structures not only in furniture construction but also in traditional wooden architecture, especially in constructions without nails. This study was performed to determine the effects of particular factors such as the axis of assembly, types of material, and adhesive on the tensile performance of various modern and traditional types of wooden corner joints. For this purpose, various corner joint specimens were prepared with three different wooden materials: Scots pine (Pinus sylvestris Lipsky) wood, Lombardy poplar (Populus nigra Lipsky) wood, and Medium Density Fibreboard (MDF) using two different adhesives: polyvinyl acetate (PVAc) and polyurethane (Desmodur-VTKA) glues; and five different wooden joint types: dowel, tongue-and-groove, half-blind dovetail, screw, and eccentric screw joints. Tensile performance tests, vertical and parallel to the axis of assembly, were carried out according to ASTM D 1037 guidelines. Experiments indicated that, while the tensile performance of MDF specimen connected with a screw and PVAc adhesive was the highest under loading parallel to the axis of assembly (4592 N); it was the lowest under loading parallel to the axis of assembly in MDF specimen connected with tongue-and-groove joint and PVAc adhesive (260 N), respectively. As a result, it may be advantageous to apply screwed joints in corners for high tensile strength in parallel to the axis of the assembly. Kutni su spojevi kritične točke drvnih konstrukcija ne samo u proizvodnji namještaja nego i u tradicionalnoj drvnoj arhitekturi, posebice u konstrukcijama bez čavala. Ovo je istraživanje provedeno kako bi se utvrdili učinci specifičnih čimbenika kao što su os montaže, vrsta materijala i vrsta ljepila na vlačna svojstva različitih modernih i tradicionalnih vrsta drvnih kutnih spojeva. Za tu su svrhu pripremljeni različiti uzorci kutnih spojeva od tri vrste drvnog materijala: od drva bijelog bora (Pinus sylvestris Lipsky), drva lombardijske topole (Populus nigra Lipsky) i od srednje guste ploče vlaknatice (MDF), uz uporabu dvaju različitih ljepila: polivinilacetatnoga (PVAc) i poliuretanskoga (Desmodur-VTKA) te uz pet različitih vrsta drvnih spojeva: moždanika, pera i utora, poluzatvorenog lastina repa, vijka i ekscentra. Ispitivanja vlačnih svojstava okomito i paralelno s osi montaže provedena su u skladu s normom ASTM D 1037. Rezultati su pokazali da su najbolja vlačna svojstva MDF uzorka spojenoga vijkom i PVAc ljepilom p