Abstract
A 9-story steel frame reinforced concrete building which houses the architectural and civil engineering departments of Tohoku University has experienced several strong earthquake motions since its completion in 1969. Particularly, during the Miyagiken-oki earthquake of June 12, 1978, the measured response acceleration of the 9-th floor of the building was about 1000 gal which is the largest building response ever recorded. In this paper, described are 1) the damage to the building and the change of the natural period of the building due to the experience of strong earthquake motions and 2) the nonlinear response analyses of the building based on the inelastic properties of the constituent structural members during the strong ground motions. The results are summarized as follows. 1) The natural period of the building has become longer considerably as the building has been subjected to strong eathquake motions. The natural period of the building in the main part of shaking during the earthquake of June 12, 1978 was about twice as long as the initial natural period in small amplitude at its completion. 2) The calculated responses of the building subjected to the strong ground motions agreed well with the observed responses in the building. The calculated damage to structural members could interpret well the actual damage of the building in the event of the Miyagiken-oki earthquake of June 12, 1978.
