A New concept to Join Members in Frame Construction with CNC-Fabricated Timber Beams and LVL Nodes: Strength Test and Failure Analysis
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The problem of resource depletion and climate change are of great importance for both the general public and timber construction industries. Currently missing knowledge about wood-to-wood connections makes this study significant for the field of wood product research, because it represents a possible starting point for a new ecological, open source construction system to promote the usage of wood as potentially sustainable and renewable construction material. This study presents a new concept designed by the author to make joining in frame construction more efficient, sustainable for builders and to promote timber engineering. This concept uses laminated veneer lumber (LVL) as nodes in regions with a pronounced non-uniform stress distribution and sawn timber in regions with a more uniform stress distribution. No metal fasteners or adhesives are used in the region of joining between node and beams. The concept is intended to be manufactured with 3-axis CNC machinery and to be a system for on-site- and pre-fabrication of e.g. small houses, emergency shelters and exhibition stands. The purpose of this study was to acquire information about compressive, tensile strength and the failure of two joint designs, the simple and thick gooseneck joint. To investigate the wood joints failures, full field displacement images acquired via digital image correlation (DIC) and specimen density via computer tomography (CT) were used. The wood joints have a higher compressive than tensile strength. Both wood joints exhibited brittle failure in tension (beam and/or node failure). In compression the simple gooseneck joint buckled around the thinnest cross section of the beam and the thick gooseneck joint showed compression failure. Suggestions are made for how the mechanical properties of the joints can be improved. Finally, possible methods for future research on wood joints are outlined.
Place, publisher, year, edition, pages
2015. , 164 p.
Technology, CNC, robotic wood construction, timber engineering, wood joints, joint, prefabrication, digital image correlation, computer tomography, construction system, wikihouse, robotic manufacturing
IdentifiersURN: urn:nbn:se:ltu:diva-47446Local ID: 4fcc1632-10f5-4ec8-bcc6-ab641e683a3eOAI: oai:DiVA.org:ltu-47446DiVA: diva2:1020769
Subject / course
Student thesis, at least 30 credits
Wood Engineering, master's level
Sandberg, DickSchmid, Volker
Validerat; 20150617 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved