SUMMARYThe 11 March 2011 M 9.0 Great East Japan earthquake generated significant long-duration shaking that propagated hundreds of kilometers from the epicenter and affected urban areas throughout much of Honshu. Recorded responses of a tall building at 770 km from the epicenter of the mainshock and other related or unrelated events show how structures sensitive to long-period motions can be affected by distant sources. Even when the largest peak input motions to the building is about 3% g, the strong-shaking duration was about 140 s. The 300-to 1000-s prolonged responses of the building are primarily due to a combination of site resonance (e.g. structural fundamental frequency~0.15 Hz and site frequency~0.13-0.17 Hz) and low damping (~1-2%) of the structure. Response modification technologies can improve the response of the building during future earthquakes. The need-to-consider risks to such built environments from distant sources are emphasized.

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During the 2011 Tohoku-oki earthquake, a large number of response records from various types of buildings were obtained. The records give us the actual motions of buildings during the exceptionally large earthquakes that are considered comparable with design earthquakes. Various types of earthquake response records have been collected, and their properties with several buildings that will exhibit implications for structural design are discussed.

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To grasp the effects of creep characteristics and rising temperatures on lead rubber bearings under wind load, long-duration cyclic loading tests and real-time online tests were conducted. From the loading tests, the lateral restoring characteristics of the lead rubber bearings in the small deformation range considering the creep characteristics were obtained. Analytical results using a simplified estimation method considering the small deformation characteristics of lead rubber bearings agreed well with the test results. From the online tests, the response properties of a base-isolated building under wind load were experimentally verified, and the validity of the modeling approach for lead rubber bearings and the wind response analysis method were confirmed.