スチフナ補強の効果を考慮した薄肉ウェブ梁の合理化設計法
作用せん断力が小さい大スパンH形断面鉄骨梁では，ウェブ板厚を小さく設計して鋼材コストを削減することができる。このとき，幅厚比が大きい梁では局部座屈による早期の耐力低下が懸念されるため，曲げ応力が大きい材端部にはスチフナと呼ばれる補強鋼板を設けて必要な部材性能を確保する手法が広く用いられている。一方で，スチフナ配置と補強効果の関係について定量的な知見は乏しく，個々の部材条件によらない補強要領を一律に用いることで過剰な設計が行われることも多い。そこで本研究では，部材条件と必要性能に応じてより合理的な補強設計を可能とするため，スチフナ補強効果の評価法を提案し，構造実験ならびに有限要素解析を通じて広範なパラメータに対してその妥当性を検証した。
キーワード：H形断面鉄骨梁，材軸直交スチフナ，幅厚比，局部座屈，塑性変形性能
＊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 技術企画部 企画室
＊３ 技術センター 都市基盤技術研究部
Rationalization of Design Method for Thin-web Steel Girders Considering Stiffener Reinforcement
When designing H-shaped steel girders with small shear force, it is possible to reduce steel cost by reducing the thickness of web plates. For steel girders with a large width-to-thickness ratio, there is concern about premature degradation due to local buckling. It is therefore common practice to reinforce the ends of such girders, where large bending stress occurs, with steel plates called stiffeners in order to ensure the required member performance. However, there is a dearth of quantitative knowledge about the relationship between stiffener placement patterns and the reinforcement effect, so thin-web steel girders tend to be overdesigned by applying code-specified reinforcement criteria without considering individual member conditions. In this study, we propose a method for evaluating the reinforcement effect of stiffeners to enable more rational design according to individual member conditions and performance requirements. The reliability of the proposed method is also verified for a wide range of parameters through loading tests and finite element analysis.
Keywords: H-shaped steel girder, intermediate stiffener, width-to-thickness ratio, local buckling, plastic deformation capacity
*1 Structure Research Section, Urban Engineering Research Department, Taisei Advanced Center of Technology
*2 Planning Section, Technology Planning Department, Taisei Advanced Center of Technology
*3 Urban Engineering Research Department, Taisei Advanced Center of Technology