重ね継手部対応型Head-bar®を用いたRC柱部材の靭性に関する検討
大断面のRC橋脚では，帯鉄筋の重ね継手部に中間帯鉄筋を配置する必要がある。従来の半円形フックを重ね継手部に用いる場合には，重ね継手部の2本の鉄筋にかけることが標準であり，機械式定着鉄筋においても同様に配置するためには鉄筋2本分に掛けられる長さのプレートを有するもの（以下，重ね継手部対応型Head-bar）を使用する必要がある。本研究では，前述の重ね継手部対応型Head-barを中間帯鉄筋として適用したRC柱部材の正負交番載荷実験を行い，靭性が半円形フックを適用した場合と同等であること，設計上の変形性能を満たすことを確認した。その後，終局後の破壊過程におけるプレートの変形性能向上のため，プレートを増圧し，3次元FEM解析により変形状態と発生応力を確認した後，再度部材実験を行い，設計上の終局点以降の破壊領域においてもHead-barのプレート部が変形しないことを確認した。
キーワード：重ね継手部，プレート定着型せん断補強鉄筋，中間帯鉄筋，正負交番載荷実験
＊１ 技術センター 社会基盤技術研究部 材工研究室
＊２ ブイ・エス・エル・ジャパン（株）
Study on Ductility Performance of RC Column Members with Head-bar for Lap Splices
In large cross-section RC bridge piers, it is necessary to provide cross tie reinforcement at the lap splices of hoop reinforcement. When a conventional semi-circular hook is used at a lap splice, it is standard to hang the hook on both of the bars forming the lap splice, and likewise for mechanical anchorage reinforcement, it is necessary to use anchorages with a plate of sufficient length to enable it to be hung on the two bars (hereafter referred to as “lap splice Head-bar”). In this study, positive and negative cyclic loading tests were conducted on RC column members to which lap splice Head-bars were applied as intermediate hoop reinforcement. From the results it was confirmed that the ductility performance was equivalent to the case where semi-circular hooks were applied and that the design deformation performance was satisfied. The plates were then pressurized to improve the deformation performance of the plates during the ultimate failure process. The deformation state of the Head-bar under increased pressure and the stress generated were confirmed by three-dimensional FEM analysis. The Head-bar plates were then tested again, and it was confirmed that the plates were not deformed even at the design ultimate failure and beyond.
Keywords: lap splices, plate anchorage type shear reinforcement bars, intermediate hoop reinforcement, positive and negative cyclic loading tests
*1 Structure and Material Research Section, Infrastructure Technology Research Depatment, Taisei Advanced Center of Technology
*2 VSL Japan Corporation