IMPROVEMENT OF STRENGTH DETERIORATION FOR RC COLUMNS USING LONGITUDINAL BARS WITH PARTIALLY LARGE LUG

今日，危機耐性確保に配慮するために，RC柱の急激な荷重低下を改善させることが重要となっている．本研究では，軸方向鉄筋の節の一部を高くすることによる付着特性向上が，RC柱の荷重低下挙動にどう影響するかを正負交番載荷実験により検討した．その結果，軸方向鉄筋の節の一部を高くすることにより，付着割裂ひび割れの進展が抑制され鉄筋の付着特性が向上すること，また，その付着特性の向上が同一振幅載荷での軸方向鉄筋の座屈抑制につながることを示した．そしてこの軸方向鉄筋の座屈抑制の要因が，座屈時の鉄筋の両端固定条件が維持されたこと，また，それにより座屈長増大が軽減したことであると推測した．そこで，座屈長の変化に着目したRC柱の非線形静的解析を行い，本実験におけるRC柱の挙動を再現するための今後の課題を示した．In order to improve seismic performance, it is important to prevent rapid strength deterioration of RC columns. In this research, longitudinal bars with partially large lug were proposed for improvement of strength deterioration of RC columns, and the cyclic loading tests for RC columns were conducted. As the results, large lugs could control the occurrence of bond splitting cracks on RC columns surface, and bond characteristics of longitudinal bars with partially large lug was well-improved. Furthermore, by large lugs, both ends fixed boundary condition was maintained, and buckling length was prevented from becoming longer. In consequence, buckling of longitudinal bars became hard to occur, and rapid strength deterioration was prevented. Based on this result, pushover analysis of RC columns was conducted using buckling length as a variable. As a result, it was found that a general model of reinforcement buckling model wasn't able to reproduce strength deterioration with the same amplitude