EFFECTS OF SEISMIC RETROFITTING ON REINFORCED CONCRETE BUILDINGS SUFFERED DURING THE 2004 MID NIIGATA PREFECTURE EARTHQUAKE

This study reports on the relation between seismic performance and damage of buildings during the 2004 Mid Niigata Prefecture Earthquake. Two buildings under construction for retrofitting were studied. One of them had light damage, another had negligible damage. A building with light damage had four columns with damage level of Ⅳ during the Earthquake. And the remaining seismic performance of the building was 89 %. Evaluated seismic performance index (Is value) of the long span direction of the building was 0.58~0.79. The lack of seismic performance was assumed to be a cause of the damage on the building. On the other hand the Is value of another building was 0.44~0.71 although the damage of the building was negligible. Finally the effect of the seismic retrofitting for two buildings was discussed comparing the relationship between damage level and the seismic performance indices which varied depending the retrofitting process.