Change in Dynamic Characteristics of Base-Isolated Buildings With Irregular Shape Based on Long-Term Vibration Records

Abstract

Long-term structural health monitoring is conducted on the Toyosu campus of Shibaura Institute of Technology. The buildings are installed with accelerometer sensors and incorporated with base isolation devices, which are also installed in the ground. The fast Fourier transform (FFT) was used to analyze the microtremor records for nine years. The result shows a negative correlation between temperature and the natural period of the buildings, and the periods have increased by approximately 5% since the 2011 off the Pacific coast of Tohoku Earthquake. The auto-regressive exogenous (ARX) model was used to analyze the earthquake records. The result shows that the natural period and damping ratio of buildings are dependent on the amplitude of vibration. The periods have increased by 6%-10% due to the abovementioned earthquake, but the damping ratios have not changed.