Promotion of Seismic Retrofitting for Existing Low Earthquake Resistant Structures: The Most Important Issue for Earthquake Disaster Reduction

Abstract

Much attention has been paid recently to a scandal involving faulty designed and constructed apartments in Japan. This situation is highly regrettable and it is needless to say that it is important to take measures to prevent the recurrence of these problems. These circumstances have put the public’s attention on the issue of structural seismic resistance. In Japan, besides the faulty apartments in the news recently, there are many existing buildings that were designed and constructed following the former structure code, and do not have enough strength as required by the current code These structures are called pre-code revision weak structures. They are widely spread throughout the country and used for apartments, offices and hotels, etc. The number of these structures is approximately 1.5 million, which is 10,000 times more than faulty apartments. If we consider wooden houses, the most typical residential houses in Japan and more vulnerable, the number of pre-code revision weak houses is over 10 million and the situation is even worse. Imagine what would happen when an earthquake occurs. Obviously not only the faulty apartments will be affected, but other many pre-code revision weak structures will also be damaged. Seismic reinforcement of such structures is urgently needed for earthquake disaster reduction.