Seismic Isolation Retrofit for Large-Scale Government Building Identified as Cultural Assets
Structural Engineering Department, NIKKEN SEKKEI Ltd., Japan, 4-15-32 Sakae, Naka-ku, Nagoya 460-0008, Japan
The Aichi Prefectural Government building in Nagoya, designated a national registered cultural asset and an important disaster prevention facility, was found in 2002 to be seismically inadequate for anticipated earthquakes. While seismic retrofitting has been considered, however, no report has, to our knowledge, compared retrofitting alternatives in depth. The building is located in a Nagoya district scheduled for disaster prevention measures anticipating the Tokai and Tonankai earthquakes – two “super shakers” expected to devastate major Japanese cities, including Tokyo, and decimate the urban population in the not too distant future. These quakes are expected to produce long-term earthquake movement with amplified long-period components and to damage long-period structures such as skyscrapers and base-isolated buildings. In 2003, we selected seismic retrofitting as the optimum answer given the prefectural building’s features. We made objective comparisons working with academic experts and, in 2004, jointly examined the building using simulated earthquake motion based on the latest knowledge and data, making the main building a highly earthquake-resistant structure. This paper reports our findings and the aftermath of recommendations. The building appearance and building structure conception diagram are shown in Fig. 1.
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