In this paper, equivalent linearization technique is applied to wooden houses. In the early part of the paper, equivalent period and damping are defined from non-linear time history analysis and shear wall tests. Thereafter the comparison with shaking table test and proposed equivalent linearization technique is described in the maximum displacement.

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Earthquake observation is carried out on the Tokyo campus of Shibaura Institute of Technology. Accelerometer sensors are installed at the buildings incorporating base isolation devices and in the ground. Observed horizontal orbits from relative-story displacement meters indicate that not only lateral vibrations but also rotational vibrations occurred between basement and first floor due to the irregular-shaped building. In this paper, a method is proposed to estimate lateral and rotational vibration amplitude from seismic records. This method is applied to the acceleration records observed during the main shock of the 2011 Great East Japan Earthquake. At the result, the maximum rotation angle is 3.8x10-4 rad and maximum lateral displacement is 6 cm are estimated.

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Due to the 2011 off the Pacific coast of Tohoku Earthquake, although many structures were heavily damaged by tsunami, most bridges designed by post-1990 code were not damaged by ground motion. However, in some bridges designed by post-1995 code, rubber bearings were severely damaged. In this study, to estimate strong ground motions at the 4 damage sites (Rifu Viaduct site, Tobu Viaduct site, Asahi Viaduct site and Shin Nakagawa Bridge site) with high accuracy, temporary aftershock observations were conducted at the bridge sites. Site effects at the bridge sites were evaluated based on the observation records. Strong ground motions at the bridge sites during the 2011 main shock were estimated considering the empirical site amplification and phase effects. The estimated ground motions will be useful in detailed study of the failure mechanism of the rubber bearings.

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During the 2011 off the Pacific coast of Tohoku Earthquake, a lot of serious damage occurred to embankments in Yamamoto Town, Miyagi Prefecture, Japan. In this study, to evaluate ground motions at the damage sites, temporary aftershock observation was conducted at the sites. The result indicates that the ground motions at the damage sites were similar to those at either of the strong motions stations, namely, “KiK-net Yamamoto" or “Yamamoto Town Office". At Yamamoto Town Office, where the main shock waveforms were not recorded, the waveforms were estimated based on the extended site-effect substitution method.

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