Abstract
The study reported was made experimentally on the damping of building, considering mainly the effect of the pile foundation and the surface layer upon the building vibration. In the experment, were used the models of single-story building and piles both made of steel, and a rubber sheet for the surface layer. The models were subjected to the free, force and randam vibrations in the following cases, 1) Building fixed at foundation (B), 2) Suface Layer only (S.L.), 3) Combined system (F+S.L.) of, that is of pile fouudation (F) and surface layer, and 4) Combined system (B+F+S.L.), that is of building and pile foundation with surface layer, and cases of 2), 3) and 4), in which the surrounding of surface layer was treated in both ways such as restrained and free. From the results of experiment, the following facts have been proved. In the case of the surface layer of which surounding is restrained, the damping of combined system (B+F+S.L.) is much influeced by the swaying, and it approaches that of (F+S.L.) as the swaying becomes larger. A similer tendency can be seen in the period of vibration. In the case of the surface layer with a free boundary, the mode of vibration of combined system (B+F+S.L.) is much dominated by the vibration mode of surface layer (S.L.) or by that pile-foundation building (B+F), and the damping of (B+F+S.L.) approaches that of S.L. or of (B+F), as similarly to the tendency which we have seen in the mode of vibration of models.
