高強度高靭性SFRC を用いたI 形梁の曲げ・せん断挙動に関する実験的・解析的評価
吉田 昂平＊１・村田 裕志＊１・川端 康平＊１・畑 明仁＊１設計基準強度80N/mm2程度のコンクリートに高性能鋼繊維を混入した，高強度・高靭性な鋼繊維補強コンクリート（SFRC）を各種部材に用いることで，鉄筋を大幅に省略できる。当社では，上記の鋼繊維を利用した安価なSFRCを開発した。しかし，SFRCに関して鋼繊維の引張力に対する効果を考慮した設計基準は整備されておらず，構造性能の把握が重要となる。したがって，上記SFRCについて曲げ・せん断などの構造性能を把握するため，I形梁の載荷実験を行った。載荷実験では，せん断スパンの異なる2タイプのI形梁に対して，鋼繊維の混入量を変化させて耐力を比較した。また，上記実験に対して有限要素法による再現解析を行った。解析では，自己収縮による収縮ひずみや鋼繊維の配向性や分散性による，SFRCの力学的特性のばらつきを考慮したモデル化を行い，それらの構造性能に対する影響を確認した。
キーワード：高強度鋼繊維補強コンクリート，I形梁，非線形有限要素解析
＊１ 技術センター 社会基盤技術研究部 材工研究室
Experimental and Analytical Evaluation of Flexural and Shear Behavior of High-Strength and High-Toughness SFRC I-beams
Using high-strength and high-toughness steel fiber reinforced concrete (SFRC) in which high-performance steel fiber is added to concrete with a design characteristic compressive strength of about 80 N/mm2 in various members can contribute to significant reductions in reinforcement. At Taisei, the authors have developed low cost SFRC using this steel fiber. However, there are no design standards for SFRC that can take into consideration the effect of the tensile strength of the steel fiber, so it is important to confirm the structural performance of SFRC. In this study, the authors conducted loading tests on I-shaped SFRC beams in order to determine their loading performance in bending, shear, etc. In the loading tests, the amount of steel fiber was varied and two types of I-shaped beam with different shear spans were used, and the load resistance results were compared. Also, finite element analysis was performed to reproduce the experimental results. In the analysis the effect of variations in mechanical properties of the SFRC due to the effects of shrinkage strain due to self-shrinkage, orientation of fibers, and distribution of fibers was taken into consideration, and their effect on structural performance was confirmed.
Keywords: high-strength steel fiber reinforced concrete, I-shaped beam, nonlinear finite element analysis
*1 Structure and Material Research Section, Infrastructure Technology Research Department, Taisei Advanced Center of Technology