質量変化に伴う振動数変化に基づいた微小振幅時の免震層の剛性推定

概要

論文の詳細を見る
We try to identify the stiffness of a base-isolation layer for a large-scale base-isolated structure in Fukuoka. Our method is based on the fact that the natural frequency of a structure will be modified by certain amount when we increase the mass of that structure. If we know a-priori the amount of added mass, then we can invert both the stiffness and the original mass at the same time. We applied the method for the multiple frequency data of a base-isolated building obtained through microtremors during construction period. Since the level of microtremors is on the order of micron, the resultant stiffness will be those for microscopic loading. The stiffness of the base-isolation layer that we inverted is unanimously higher than the value used for design, about three times. To explain the difference we use the same technique to obtain the real stiffness of rubber bearings. We found that they are about twice as large as that used for design. Based on these two facts we deduced that lead dampers should have five times larger stiffness, provided that the hysteretic steel dampers would not show any strong strain dependency.
社団法人日本建築学会の論文
2005-04-30