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As a result of the 2010-2011 Canterbury earthquakes, over 60% of the concrete buildings in the Christchurch Central Business District have been demolished. This experience has highlighted the need to provide guidance on the residual capacity and repairability of earthquake-damaged concrete buildings. As limited testing has been performed on repaired components, this study focuses on the performance of severely-damaged lightly-reinforced concrete walls repaired through replacement of reinforcement and concrete in the damaged region. The damage prior to repair included buckling and fracture of longitudinal reinforcement, crushing and spalling of concrete, and, for one of the two specimens, out-of-plane instability of the gross section. Prior to repairing the wall specimens, tensile testing of reinforcement with welded connections was conducted to verify acceptable performance of welds suitable for reinstating the damaged reinforcement. Repairs to the specimens consisted of removal of damaged concrete through either hydrodemolition or jack hammering, followed by cutting and removal of damaged reinforcement and reinstatement of new reinforcement and repair mortar. The two repaired wall specimens were tested using a standard protocol that was identical to that used for one of the two original wall specimens. Aside from a difference in the elastic stiffness, the load-deformation responses of the repaired specimens were similar to that of the originally-tested specimen through to the first loading cycle at 2.0% drift, beyond which strength degradation was more pronounced for the repaired specimens. The overall performance of the repaired walls relative to the original wall indicates that it is feasible to achieve acceptable performance of severelydamaged concrete walls repaired through replacement of reinforcement and concrete in the damaged region. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study conducted to investigate the seismic performance and out-ofplane response of three rectangular doubly reinforced ductile wall specimens subjected to an in-plane cyclic quasi-static loading. The specimens were half-scale, representing the first story of four story prototype walls designed according to NZS3101:2006. The experimental program including details of the specimens, material properties, test setup, loading protocol and instrumentation is described. Also, the test observations, with focus on the significant stages of wall response as well as the failure patterns of the specimens, are reported considering the correlation between seismic damage and lateral drift. Two of the specimens failed at 2% drift, and their failure modes comprised of bar fracture, bar buckling, concrete crushing and out-of-plane instability. The failure pattern of the third specimen was pure out-of-plane instability which proved to have the potential to cause sudden collapse of slender ductile walls that are designed to resist other failure modes. In light of the test results, the efficacy of wall design provisions in the New Zealand concrete design standard (NZS3101) associated with the observed failure modes is scrutinised. [ABSTRACT FROM AUTHOR]