Development of wood-frame joints for easy selective dismantling

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15580145
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 林産科学・木質工学
• Research Institution: Mie University
• Principal Investigator: UCHISAKO Takayuki Mie University, Faculty of Bio-resources, Research Associate, 生物資源学部, 助手 (80232841)
• Co-Investigator(Kenkyū-buntansha): TOKUDA Michio Mie University, Faculty of Bio-resources, Professor, 生物資源学部, 教授 (50012018)
• Project Period (FY): 2003 – 2005
• Keywords: wood-frame joints / selective dismantling / removal failure of fasteners / steel pipe drift pin / column-sill joints

Research Abstract

To develope wood-frame joints which are easy to dismantle and salvage structural members, laber time to install and remove common wood fasteners (nails and wood screws) with various lengths were measured and the percentage of removal failure which makes the materials unsuitable for reuse was evaluated at first. The results were that 1) it took more time to remove nails than screws and removal time of nails increased with increasing length of nails, 2) 2.4% of total 220 screws were failed to be removed because of their slots of heads broken at installation while the percentage of removal failure of nails were 1.2% of total 220. These result showed that screws have an advantage over nails in that they are more easily withdrawn, but need careful installation to avoid their slots to break and that large-diameter dowel-type fasteners such as bolts, lag screws and drift pins were more suitable for easy deconstructions considering about this problem.
On the basis of these results, new column-sill joints were developed using bolts or drift pins in this study. The joint designed consists of a steel pipe connector (φ16, 210mm length) inserted into a bored hole at the end grain of columns and fastened by three steel pipe drift pins (φ12) having screw threads at the end. This joint needs no tenon and can be simply processed by power dorills. Drift pins are made of lightweight steel pipes and easy to be pulled out by power driver dorills using threaded parts. In vertical pull-up tests of the column-sill joints, the joints had 15kN allowable strength and were confirmed to be in practical use.