Mechanical analysis of shear behavior of mechanical joints with decayed wood

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07870
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Wood science
• Research Institution: Hokkaido University
• Principal Investigator: Sawata Kei 北海道大学, 農学研究院, 講師 (10433145)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 降伏理論 / 非線形解析 / 降伏耐力 / 初期剛性

Outline of Final Research Achievements

Timber joints are important for structural performance of wooden house. Structural performance of wooden house is change by decay. Accordingly, it is important to obtain relations between decay and performance of timber joints. Decay often is not uniform in cross section of wood. Relations between decay distribution of wood and shear behavior of mechanical joints were investigated. When neighborhood of nail head was decayed, the strength of joints was lower than the joints which had decay near nail tip. The yield strength of nailed joints with both of sound and decay parts was calculated based on European yield theory. The calculated values were close to the experimental results. Non-linear analysis was conducted on mechanical joints with slotted-in steel plate. When wood near steel plate was decayed, the joints were showed the small initial stiffness and yield strength.

Free Research Field

木質構造

Academic Significance and Societal Importance of the Research Achievements

本研究では木材内の腐朽部の位置や、腐朽の範囲が接合部の性能に及ぼす影響を調べた。その結果、腐朽分布を有する接合部のせん断挙動を、降伏理論および非線形解析を用いて定性的に評価することができた。これにより、腐朽発生時における接合部のせん断抵抗メカニズムが明らかとなり、学術的に意義深い。またこの成果は木造住宅の劣化診断として社会還元できる。今までの木造住宅の劣化診断は腐朽の有無によって判断していた。しかし本研究の成果を活用すれば、劣化診断時に腐朽部位や腐朽範囲の情報から接合部の残存性能が推測できるため、工学的論拠に立った木造住宅の保全計画が実施できる。