現行の設計では大規模地震に対して，構造物にある程度の損傷を生じることを前提としているが，土木構造物は長期間供用されることが多く，設計耐用期間内に複数回の損傷を受ける場合が十分想定される．損傷した構造物を短期間に復旧することは，構造物に要求される性能の一つとして位置づけられ，復旧性等と呼ばれている．これに関連して，一度損傷した部材を修復した後の部材性能について研究が進められているが，複数回の損傷と修復を繰り返した場合の部材性能について研究した事例はほとんどない．そこで，本研究では，損傷と修復を繰り返したRC部材の性能に関する実験的な検討を実施した．その結果，再修復後の部材性能は，初回の修復後と同様の傾向を示し，修復前の軸方向鉄筋の損傷程度と補修方法の影響を受けることを明らかにした．

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 A simultaneous crack extension pull-out model for post-installed anchor is presented. The anchor is such that used in various strengthening techniques for reinforced concrete structures. The properties of the infill material used for post-installed anchor are characterized by a nonlinear interface between the surrounding concrete and the anchor. This is a new type of anchor-infill assembly in which the infill material is divided into two layers for the purpose of providing a larger failure path length resulting in increase of energy absorption and pull-out load capacity. The mechanical properties of the infill layer are different from the surrounding concrete. Therefore, the existing pull-out model of deformed bars cannot be applied directly in this case. The interfacial de-bonding is examined by the strength criterion expressed in terms of interfacial shear stress. Pre-existing cracks representing artificial notches are assumed at the top of infill layers for identifying crack location and stabilizing its propagation direction. All the possibilities associated with two-cracks in the close vicinity have been investigated in detail. The objective of the analysis is to predict a set of material properties which result in simultaneous crack extension at the two interfaces and also to identify a simultaneous crack extension length which results in increasing the pull-out load capacity, energy absorption and failure path length, achieved at lowest increase in pull-out deformation. Limiting the pull-out deformation is desirable from the point of view of limiting damage. From the analysis, using proposed material properties and dimension parameters, simultaneous crack extension length, L_d equal to 0.3 is identified as the ideal length which results in increasing the pull-out load capacity by 31%, increasing the failure path length by 30% and increase the energy absorption capacity by 47% achieved at an limited increase in pull-out displacements of 20%.

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