抄録
This paper attempts to examine the change in dynamic characteristics (natural frequency, equivalent damping constant) of the selected 48 apartment houses of five-storeyed reinforced concrete structure, measuring their micro-tremor in the different phases of construction mainly with respect to the changes corresponding to the size and shape. The measured values are compared with the theoretically computed ones for the rocking vibration of rigid body on an elastic ground. Summary is as follows : 1. Dynamic characteristics of structure become to clear when the condition is fulfilled, that is l_0/b(height/width)≥ and N(story)≥3; when not, the vibration of ground itself is transmitted directly to the structure on account of the greatness of damping degree in ground-structure system. 2. Natural frequency correlates to the size and shape of structure. Measured values become lower when increased the l_0/b, which tendency in general accords with theory. 3. Equivalent damping constant, though showing variation, tends to decrease when increased the l_0/b or decreased the natural frequency of structure. The measured values are, however, comparatively lower than the theoretical ones. 4. Influences of ground upon the dynamic characteristics of structure are plain enough about the natural frequency, which on natural ground shows higher values about 10% than on fill-up ground. However, influences upon equivalent damping constant are not clear.
