Damage level classification is essential just after a damaging earthquake for decision of appropriate and necessary action in order to prevent from repeated damage due to after-shocks and future major earthquake, and to support well-organized recovery. Therefore, accurate and practical post-earthquake damage evaluation method has been studied and developed in Japan. This paper overviews state-of-the-art of post-earthquake damage and residual seismic capacity for reinforced concrete buildings in Japan. Japanese Damage Evaluation Guideline was originally issued in 1990 and revised in 2000 and 2015. Evaluation of residual seismic capacity of whole building was introduced in the 2000 revision, in which deterioration of each structural component is evaluated based on damage level considering residual crack, crush of concrete and so on. Total collapse mechanism and damage in non-structural concrete wall were taken into the scope in the 2015 revision. Recently, residual seismic capacity evaluation based on response spectrum method is studied by authors. Basic concept of these method and application example are presented.

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On October 15, 2013, a magnitude 7.1 earthquake severely damaged buildings on Bohol Island, the Philippines. This paper briefly reports on the typical damage to reinforced concrete (RC) buildings observed in the authors’ post-earthquake investigation. The current study focuses on the seismic performance of an earthquake-damaged building with exterior beam-column joint failure. Cyclic loading tests were conducted to propose a practical seismic strengthening method by installing RC wing walls for substandard moment-resisting frames with brittle beam-column joints. A scaled model representing the earthquake-damaged frame reproduced the damage to the exterior beam-column joint, which could not be evaluated using Japanese seismic evaluation methods because of an overestimation of the joint performance. Another specimen strengthened by the proposed method was successfully upgraded, forming a ductile beam yielding mechanism. The ultimate strength of the upgraded specimen estimated by the Japanese methods agreed well with the experimental results. The strengthening mechanism by wing walls was elucidated, knowledge of which will be useful for future applications to substandard buildings in developing countries.

This is the first of two companion papers addressing the residual axial capacities of shear-damaged reinforced concrete columns. To evaluate the residual axial capacity, this article presents an arch resistance model that is based on the theory of mechanics and can reasonably explain the collapse mechanism of shear-damaged reinforced concrete columns. In the proposed model, the residual axial capacity of the column is evaluated by considering the interaction between the contributions of the longitudinal bars and the concrete core rather than by simply adding the two contributions together. The proposed model is also verified using an experimental database of shear-damaged reinforced concrete column specimens compiled from previous studies. The result shows that the proposed arch resistance model has an improved level of accuracy for evaluating the residual axial capacities of most column specimens. However, because the available information about column specimens in the compiled experimental database is limited, it is difficult to further verify the proposed model, and a new experimental program will be presented in Part 2.

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