Seismic Design for the Sustainable City: A Report on Japanese Practice

Advances in seismic design technology today enable structural engineers to design buildings with a variety of seismic safety levels corresponding to different demands of the society. However, target of design is basically limited to secure life safety level within relatively short time span, i.e., serviceable life of each building. Aspects of constructing sustainable cities, which consists of buildings with long life, are not taken into account in general. Strong earthquakes occur at intervals that are longer than life of individual building or people. On the other hand, as life of cities is obviously much longer, the corresponding seismic action is stronger than the design action and may cause serious damage in buildings designed for their life only. Taking these into account, we have to design each building for earthquakes considering the life of cities in order to secure continuity of urban activities over disastrous earthquakes. However, there are problems to be solved in order to implement such seismic design. In this paper, factors in seismic engineering that hinder to realize long life city are identified and discussions on future steps of structural engineers to contribute in constructing sustainable society are indicated.