鉄骨建築物を対象としたCLT耐力壁の開発
靭性型LSBを用いて
中大規模建築物での更なる木材活用のため，鉄骨建築物に適用可能なCLT（直交集成板）による耐力壁の開発を目指した。特に，耐力壁の接合部にはボルト内蔵型のラグスクリューボルト（LSB）を用いることで，明確な降伏耐力の発現と高靭性の確保を図った。CLT板の4角にLSBを配置し，上下の鉄骨梁と接続金物を介して接合し，層間変形時の回転モーメントをLSBの引張力とCLT木口面の支圧による圧縮力で負担させる設計である。構造実験では，LSBの内蔵ボルトが降伏後に全長に渡って伸びることで高い靭性を発揮すること，ドリフトピン接合部に長孔を設けることでさらに靭性を増大できることが確認された。また，開発を通じて，周辺架構の剛性によって耐力壁の発揮する構造性能や破壊性状が変化することを明らかとした。
キーワード：鉄骨造，CLT，ラグスクリューボルト，ドリフトピン，構造実験，耐震壁
＊１ 技術センター 都市基盤技術研究部 木・鋼研究室
＊２ 設計本部 構造設計第二部
Development of CLT Shear Wall for Steel Buildings
Application of High-Ductility Lag Screw Bolts
In order to further promote the use of timber in medium to large buildings, a structural system incorporating shear walls made of cross-laminated timber (CLT) applicable to steel-framed buildings was developed. Lag screw bolts (LSBs) with embedded bolts were employed at shear wall joints to achieve a clearly defined yield strength and ensure high ductility. LSBs were placed at the four corners of the CLT panels and connected to the upper and lower steel beams via steel connectors. This design allows the rotational moment generated during inter-story deformation to be resisted by the tensile force of the LSBs and the compressive force due to bearing stress on the end grain of the CLT. Structural experiments confirmed that the embedded bolts in the LSBs exhibit high ductility by elongating along their full length after yielding, and that ductility can be further enhanced by incorporating slotted holes at drift pin joints. The study further clarified that the structural performance and failure modes of the CLT shear walls are influenced by the stiffness of the surrounding structural frame.
Keywords: steel structure, cross-laminated timber, lag screw bolt, drift pin, structural experiment, shear wall
*1 Wood/Steel Structure Research Section, Urban Engineering Research Department, Taisei Advanced Center of Technology
*2 Structural Engineering Department II, Design Division