Proposal of general design method of column base connections subjected to large axial force for mid-to-high-rise wooden buildings

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02305
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: Building Research Institute
• Principal Investigator: Yamazaki Yoshihiro 国立研究開発法人建築研究所, 材料研究グループ, 主任研究員 (70644425)
• Co-Investigator(Kenkyū-buntansha): 秋山 信彦 国土技術政策総合研究所, 建築研究部, 主任研究官 (20806054) ; 松田 和浩 名城大学, 理工学部, 准教授 (80567397)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 集成材 / CLT / 木口 / 支圧 / 引きボルト式接合 / 複合応力

Outline of Final Research Achievements

In this research, technical issues on evaluation of compression of wood perpendicular to the grain are resolved while seismic design method for column bottom joint subjected to large axial force and bending moment for mid- to high-rise wood buildings is proposed.
Experiments of glulam and CLT subjected to partial compression as well as shear on the butt end were conducted. The compression strength got smaller when the associated shear stress was large. In tensile bolted glulam joint with rectangular notched hole, the tensile strength was decrease when 80 to 90 % of compression strength had been applied.
Full-scale tests for tensile bolted glulam column bottom joint were conducted, and we confirmed that the above findings were applicable to real situation.

Free Research Field

木質構造

Academic Significance and Societal Importance of the Research Achievements

木口面における支圧とせん断の複合応力の影響が明らかとなり、木口面の支圧に期待した柱脚接合部においては、せん断力の処理を木口の摩擦に期待することなく、別途シアキーを適切に設けることの必要性が示された。
圧縮強度の80～90%以上の圧縮応力を事前に経験すると、その後の引張強度が明確に低下する現象について、木材の基準強度は信頼水準75%の5%下限値で規定されているため、設計で基準強度以下とすれば実強度の80%ほどには達しないと考えられるが、保証設計で必要となる材料強度の安全率を設定する際には有用なデータが得られた。