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後施工プレート定着型せん断補強鉄筋による耐震補強工法の展開

Post-Head-bar工法の施工実績と適用範囲の拡大

岡本 晋*1・三桶 達夫*1・堀口 賢一*1・岡本 修一*2・中條 基*3・府川 徹*3

供用中の既設地下構造物に対して,部材の片側(内空側)からのみの施工が可能で,かつせん断耐力のみを向上させることができる後施工タイプの耐震(せん断)補強工法,Post-Head-bar工法は,2009年4月までに30件の耐震補強工事に適用され,42,000本以上の施工実績がある。また,Post-Head-bar工法の適用範囲拡大のため,太径鉄筋と高強度鉄筋を用いた場合の性能を,壁を模したはり状試験体の正負交番載荷試験を行うことにより検証した。その結果,太径鉄筋としてSD345のD29を用いたケースと高強度鉄筋としてSD390のD25を用いた場合も,所要のせん断補強効果が確実に得られることが明らかとなった。

キーワード:  既設構造物,耐震補強,せん断補強,後施工プレート定着型せん断補強鉄筋,施工例,太径鉄筋,高強度鉄筋

*1 技術センター 土木技術研究所 土木構工法研究室
*2 土木本部 土木技術部
*3 成和リニューアルワークス(株)

Implementation of Post Shear Reinforcing Methods Using Plate Anchored Shear Reinforcing Bar Technology

Examples of Application, and Extension to Large-diameter and High-strength Reinforcing Bars

Susumu OKAMOTO*1, Tatsuo MIOKE*1, Kenichi HORIGUCHI*1, Shuichi OKAMOTO*2, Motoshi CHUJYO*3 and Tohru FUKAWA*3

This paper describes post shear reinforcing method called “Post-Head-bar” that uses plate anchored shear reinforcing bar technology. Forty-two thousand post shear reinforcing bars already have been installed in thirty projects using this method.
In this study, loading tests were conducted to clarify the efficiency of “Post-Head-bar” comprised of D29 large-diameter reinforcing bars and SD390 high-strength reinforcing bars. The results showed that the effective factor for conventional reinforcement design is 0.8. This is the same value that is used for normal-diameter reinforcing bars (D16, D19, and D22) and normal-strength reinforcing bars (SD295 and SD345). These results ensure that a design method of reinforced structures by “Post-Head-bar” comprised of large-diameter reinforcing bars and/or high-strength reinforcing bars will be easily established with only small modification of already developed method for normal-diameter reinforcing bars or normal-strength reinforcing bars.

Keywords:  existing structures, seismic reinforcement, shear reinforcement, Post-Head-bar, application example, large-diameter reinforcing bar, high-strength reinforcing bar

*1 Civil Structure and Material Research Section, Civil Engineering Research Institute, Technology Center
*2 Civil Engineering Technology Promotion Department
*3 Seiwa Renewal Works Co., Ltd.