2021 Volume 21 Issue 4 Pages 4_65-4_85
Long-term monitoring is carried out on the Toyosu campus of Shibaura Institute of Technology. Accelerometer sensors are installed at the buildings incorporating base isolation devices and in the ground. The microtremor records for nine years were analyzed by FFT. As a result, it is found that there is a negative correlation between temperature and the natural period of the buildings, and the periods have increased by about 5% since the 2011 off the Pacific coast of Tohoku earthquake. The earthquake records were analyzed using the ARX model. As a result, it is found that the natural period and damping ratio of buildings are dependent on the amplitude of vibration. The periods have increased by 6 to 10% due to the above-mentioned earthquake, but the damping ratios have not changed.
