Recently, some repaired reinforced concrete (RC) structures were damaged by the aftershocks like the Great East Japan Earthquake 2011, and by the earthquake like Tokachi-Oki Earthquake 2003 after Kushiro-Oki Earthquake 1995. There were RC structures repeated damage and repair due to earthquakes. So, we should study not only repaired RC member's performance but also re-repaired RC member's performance. Based experimental investigations, we clarified the following: the re-repaired RC member's performance i(on) s not directly affected by the repetition of damage and repair, but affected, as repaired RC member's performance, by the damage degree of longitudinal reinforcements before re-repairing, by repair methods, and by repairing materials.

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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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