H形断面座屈拘束ブレースの開発
座屈拘束ブレースとは引張・圧縮で同等の強度と変形能力を有する鋼製の筋かい材で，軸力を負担する芯材と，芯材圧縮時の座屈を防止する座屈補剛材とから構成される。当社の座屈拘束ブレース「シェイプアップブレース」は開発から20年以上を経過し，中低層建物の耐震部材や超高層建物の制振部材として幅広く使用されてきたが，近年の鋼材価格の上昇のため，競合製品との価格優位性を損なう状況も生じてきた。そこで芯材にロールH形鋼を，座屈補剛材にモルタル充填角形鋼管を用いることで構造性能を損なわずに製作コストを低減する新たな座屈拘束ブレースを開発した。開発にあたって実大試験体15体を用いた構造実験を実施し，引張圧縮同等の塑性変形性能を確認し，座屈補剛材の補剛効果および接合部の構面外座屈性状に対する既往の設計式を準用できることを検証した。また，低降伏点鋼を用いた低サイクル疲労実験も実施し，制振部材としての性能も把握した。
キーワード：座屈拘束ブレース，Ｈ形鋼，モルタル充填角形鋼管，構造実験
＊１ 技術センター 都市基盤技術研究部 構造研究室
＊２ 技術センター 都市基盤技術研究部
＊３ 設計本部 設計企画部
Development of Buckling-restrained Brace with H-shaped Cross-section
A buckling-restrained brace is a steel brace with equal strength and deformation performance in tension and compression, consisting of a core member that bears the axial force and a buckling stiffener that prevents buckling when the core member is compressed. More than 20 years have passed since the development of our buckling-restrained brace "Shape-Up-Brace," and it has been widely used as a seismic-resistant member for medium- and low-rise buildings and as a vibration-control member for high-rise buildings. However due to the rise in steel prices in recent years, its price advantage over competing products has been undermined. In response, a new buckling-restrained brace was developed using rolled H-shaped steel as the core member and mortar-filled square steel tubes as buckling stiffeners to reduce fabrication costs without sacrificing structural performance. In the development of the brace, structural tests were conducted using 15 full-size specimens to confirm the equivalent plastic deformation performance in tension and compression, and to verify the stiffening effect of the buckling stiffener and the applicability of existing design methods for the out-of-plane buckling behavior of the joints. Also, low-cycle fatigue tests using low-yield-strength steel were also conducted to understand the performance as seismic-damping members.
Keywords: Buckling-restrained brace, H-shaped steel, mortar-filled square steel tube, structural test
*1 Structure Research Section, Urban Engineering Research Department, Taisei Advanced Center of Technology
*2 Urban Engineering Research Department, Taisei Advanced Center of Technology
*3 Operations Planning Department, Design Division