A study on hole arrangement and bearing capacity of glued laminated timber beams with multiple round holes

• Project/Area Number: 20K04796
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: Osaka Metropolitan University (2022); Osaka City University (2020-2021)
• Principal Investigator: Okamoto Shigefumi 大阪公立大学, 大学院生活科学研究科, 講師 (20769806)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2022: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000); Fiscal Year 2021: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000); Fiscal Year 2020: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000)
• Keywords: 円形孔 / 集成材 / 割裂 / 集成材梁 / 木質構造 / 建築構造・材料

Outline of Research at the Start

集成材の梁に孔を複数設ける場合、国内外の指針などで規定されてる孔の配置基準に準じる必要がある。しかし、孔の配置基準を守っても孔を複数設けると0.85程度の耐力低減が必要であることが既往の研究によりあきらかにされている。そこで本研究では、円形孔を複数有する集成材梁の耐力が低下しない孔の配置基準の提案と実務で求められる範囲で孔の間隔が短くなった時の耐力の低減方法の提案を目的として、実験及び解析により検討を行う。

Outline of Final Research Achievements

The purpose of this study is to establish a design method for the splitting strength of glued laminated timber beam with multiple round holes. First, a design method for splitting strength is proposed by formulating the ratio of the maximum tensile stress perpendicular to the grain acting around the hole as the distance between the holes decreases, using finite element analysis. Then, a three-point bending tests were conducted on a glued laminated wood beam with two round holes, and the experimental and calculated values were compared to confirm the validity of the proposed design method. In addition, we proposed a distance between the holes that would not reduce the bearing capacity.

Academic Significance and Societal Importance of the Research Achievements

日本の有孔梁の指針類は、「枠組壁工法建築物設計の手引」か「JIS A 3301」に示されている仕様規定制限のみで、有孔梁の耐力算定方法が確立されていないのが現状である。住宅などの建築現場では安全性の検討を行わずに切り欠きや孔が設けられ場合があり、適切な評価法が望まれてきた。本研究では、円径孔が一つの場合と二つの場合の耐力算定方法を提案し、この成果を応用することにより有孔梁の簡易な設計法や配置基準を検討することができ、安全な建築物の普及が期待される。

Research Products

• [Journal Article] STUDY ON STRENGTH OF GLUED LAMINATED TIMBER BEAMS WITH TWO ROUND HOLES (2023)
  • Author(s): 岡本 滋史，西村 悠汰，中谷 誠，秋山 信彦，青木 謙治，稲山 正弘
  • Journal Title: Journal of Structural and Construction Engineering (Transactions of AIJ) Volume: 88 Issue: 807 Pages: 826-834
  • DOI: 10.3130/aijs.88.826
  • ISSN: 1340-4202, 1881-8153
  • Year and Date: 2023-05-01
  • Peer Reviewed / Open Access
• [Journal Article] Study on the strength of glued laminated timber beams with round holes: proposal of the design formula for the splitting strength (2022)
  • Author(s): Okamoto Shigefumi，Akiyama Nobuhiko，Araki Yasuhiro，Aoki Kenji，Inayama Masahiro
  • Journal Title: Journal of Wood Science Volume: 68 Issue: 1 Pages: 1-18
  • DOI: 10.1186/s10086-022-02013-w
  • Peer Reviewed / Open Access
• [Journal Article] Study on the strength of glued laminated timber beams with round holes: difference in structural performance between homogeneous-grade and heterogeneous-grade timber (2021)
  • Author(s): Okamoto Shigefumi、Akiyama Nobuhiko、Araki Yasuhiro、Aoki Kenji、Inayama Masahiro
  • Journal Title: Journal of Wood Science Volume: 67 Issue: 1 Pages: 1-25
  • DOI: 10.1186/s10086-021-01941-3
  • Peer Reviewed / Open Access
• [Journal Article] Estimation of the perpendicular-to-the-grain tensile strength of Scots pine glued laminated timber via three-point bending tests (2021)
  • Author(s): Okamoto Shigefumi、Akiyama Nobuhiko、Nakamura Noboru、Aoki Kenji、Inayama Masahiro
  • Journal Title: Journal of Wood Science Volume: 67 Issue: 1 Pages: 1-11
  • DOI: 10.1186/s10086-021-01966-8
  • Peer Reviewed / Open Access
• [Presentation] 二つの円形孔を有する集成材梁の耐力に関する実験的研究 (2022)
  • Author(s): 西村悠汰，岡本滋史，中谷誠，秋山信彦
  • Organizer: 日本建築学会