A number of reinforced concrete buildings, damaged by recent severe earthquakes, required extensive repair and also strengthening. The Tokachi-oki Earthquake of 1968 heavily damaged a large number of low rise buildings. Some of these were strengthened by the addition of structural walls. These buildings are still in use. Because of the lack of guidelines, the design as well as the construction for strengthening was based on engineering judgment alone. The destructive 1978 Miyagiken-oki Earthquake was also followed by the strengthening of a number of buildings. However, in this case materials and techniques for construction were specifically selected and the design was based on experimental or analytical investigations or on guidelines, where these were available.