Analyzes on the Lateral Resistance of Nailed Timber Joints

Research Project

Project/Area Number	05660176
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	林産学
Research Institution	Hokkaido University
Principal Investigator	HIRAI Takuro Hokkaido Univ., Fac.Agriculture, Professor, 農学部, 教授 (20173205)
Co-Investigator(Kenkyū-buntansha)	TSUJINO Tetsuji Iwate Univ., Fac.Education, Professor, 教育学部, 教授 (20003965)
Project Period (FY)	1993 – 1994
Project Status	Completed (Fiscal Year 1994)
Budget Amount *help	¥2,200,000 (Direct Cost: ¥2,200,000) Fiscal Year 1994: ¥300,000 (Direct Cost: ¥300,000) Fiscal Year 1993: ¥1,900,000 (Direct Cost: ¥1,900,000)
Keywords	Nailed timber joints / Lateral resistance / Loading direction / Fracture mode / Fracture criterion / load-slip caracteristics / timber / plywood / 最大耐力解析 / 弾性床上の梁理論 / 鋼板 / 割裂破壊 / 繊維垂直方向加力 / 脆性
Research Abstract	Maximum lateral resistance and typical fracture modes of nailed timber joints were investigated both experimentally and theoretically. First, destructive single shear tests of nailed timber joints in loading perpendicular to the grain were conducted to observe their defomation and fracture behavior and the resultant maximum lateral resistance.Timber main-members and Duglas-fir plywood side-members or steel side-members were connected with CN50 or CN75 nails in the first test group.Timber main-members and timber side-members were connected with CN75 nails considering four possible combinations of grain directions of the timber members in the second test group.Test results showed the great possibility of brittle cracking fractures of timber members when they were loaded perpendicular to the grain. Second, the maximum lateral resistance and the possible fracture modes of nailed timber-plywood joints were analyzed using the theory of a beam on an elastic foundation.In which, a particular fracture criterion, "fracture bearing displacement (FBD)", which had been originally introduced by the author, was adopted to analyze the cracking fracture of timber members in loading prependicular to the grain.Punching shear of the plywood side-members was also taken into consideration, because most of the specimens loaded parallel to the grain failed in this mode.The criterion for this fracture mode was assumed that the joint failed when any part of the contour of the nail head penetrated through the plywood.These two fracture criteria were examined on every step of each analysis, then the fracture mode and the maximum lateral resistance were determined if either of them is satisfied first.The results of analyzes agreed with the test reaults in the prediction of the fracture modes, the resultant maximum lateral resistance and the maximum joint slips.