SEISMIC INTENSITY DISTRIBUTION IN TALL BUILDINGS DETERMINED FROM RESPONSES TO QUESTIONNAIRE SURVEY

概要

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The 1978 Miyagiken-oki earthquake of magnitude 7.4 did considerable, but not devastating, damage to Sendai City. The concern of persons engaged in disaster mitigation, however, was aroused because the damage that was done in Sendai is indicative of a new type of urban disaster that may be produced when large, modern metropolitan areas are struck by major earthquakes. The new types of damage done included disruption of life-line systems, and damage to new housing estates built on sloping ground, as well as to tall buildings; in particular, to their upper stories. We investigated this last type of damage by collating and interpreting responses to a questionnaire. Our survey mainly was carried out on 14-story apartment buildings at the Kawaramachi danchi (housing estate) in Kawasaki City. The accuracy of the rated intensity indicated by questionnaire answers was examined and compared with values obtained from a response analysis made for the same buildings that was based on strong motion records obtained at nearby recording stations. Compared to the ground floor, the intensity at the top floor of a 14-story building was greater by 1.0 grade on the Japan Meteorological Agency (JMA) seismic intensity scale. This phenomenon should be taken into account when establishing countermeasures for the mitigation of earthquake disasters.
日本自然災害学会の論文