STUDY OF THE EFFECT OF AMBIENT TEMPERATURE ON PREDOMINANT FREQUENCIES OF A BASE-ISOLATED STRUCTURE BASED ON LONG-TERM MICROTREMOR MONITORING

摘要

In this study microtremor measurements were conducted within the period from February to December, 2007 at the Kyushu University Hospital South Building. Firstly, we compared the spectral ratio results of this study with the past measurement results (Mori and Kawase, 2001) and it can be concluded that the construction of the North building and (or) reinforced lead dampers (after West off Fukuoka Earthquake) caused 8.2% are changed the natural frequencies from 0.97Hz to 1.05Hz in the EW direction. Secondly, we correlated spectral ratio results with the pit level temperature records. The spectral ratios of basement floor-pit level (BP) are influenced by temperature variation, i.e., when temperature increases the spectral ratio values decreases.