Revision of guideline for post-earthquake damage evaluation of RC buildings In Japan

In Japan, the Guideline for Post-Earthquake Damage Evaluation and Rehabilitation, originally developed in 1991 and revised in 2001, will be revised in 2014 based on lessons from damaging earthquakes such as the 2011 East Japan Earthquake. The authors have developed a method to evaluate the residual seismic capacity of reinforced concrete structures based on R-index, which was employed in the Damage Evaluation Guideline. The R-index is defined as the ratio of residual seismic capacity to the original capacity, and is calculated from residual seismic capacity in structural members. In this paper, firstly, the general concept of the Guideline for reinforced concrete buildings is presented. Secondly, the main points in the revision in 2014 are introduced. In the guideline revision, the value of reduction factor of capacity in a structural member corresponding to its damage state was re-evaluated with experimental data of reinforced concrete beams, columns and shear walls. An evaluation method of residual seismic capacity, R-index, for a building with total collapse mechanism of beam yielding type was developed and was introduced into the revised guideline in addition to story collapse mechanism. R-index was originally developed for a building with story collapse mechanism, which is the most typical failure mechanism of reinforced concrete buildings observed in the past damaging earthquakes. However, total collapse mechanism, which is recommended in current design code and guidelines, is found in some middle or high rise buildings damaged by recent earthquakes and this type of failure is expected to increase in the future. Applicability of the proposed method for damage evaluation was investigated by a study of the database of RC buildings damaged by the recent major earthquakes and its accuracy and effectiveness was discussed.