The material presented here is an abridged version of a paper published by the Earthquake Engineering Research Institute in "Lessons Learned Over Time - Learning From Earthquakes Series Vol. III" (EERI Publication Number: 2000-02).  A complete version of the paper can be downloaded in PDF format .

The Kobe (Hyogo-ken Nanbu) earthquake of January 17, 1995 led to a sudden and significant change in application of passive control technologies for seismic design in Japan. In the three-year period prior to the 1995 earthquake, 15 seismic isolated buildings were licensed for construction. In the three years following the earthquake, 450 isolated buildings were approved. Even today, although the construction industry has slowed substantially due to national and regional economic difficulties, licenses for approximately 10 to 15 new seismic isolated buildings are granted every month, with additional approvals for the retrofit of existing structures.

Statistics reflect similar increases in the rate of adoption of supplemental damping technologies. As is the case with most advances in earthquake engineering practice, a diverse array of technical, economic, and social influences have combined to bring about this evolution in earthquake-resistant construction.

The basic goal of this study was to understand how and why this change in engineering and construction practice has taken place. It is clear that the Kobe earthquake helped to trigger the acceptance of new technologies in the Japanese seismic design community, but the occurrence of severe earthquake shaking is not by itself enough to change the direction of engineering and construction practice.

Instead, it appears that a major factor was that passive control technologies had reached a level of maturity at about the time of the earthquake. The large human and property losses made engineers, building owners, and the general public aware of both the necessity for and the feasibility of constructing higher-performance structures and the potential benefits of improved performance.

This research focused on the opinions and experiences of the primary decisionmakers in the seismic design process--building owners, design engineers and construction companies, and regulators.  A detailed questionnaire was developed and distributed to over 150 individuals and firms.

The written surveys were augmented with visits to a number of design offices, completed buildings, and construction sites in Japan.