Estimation of Lateral and Rotational Vibrations of a Base-Isolated Building during the 2011 Great East Japan Earthquake

Abstract

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.