Abstract
Presently long-span void slabs without beams have been used often because of less restriction for making plan. Because of having a long span, large slab makes low natural frequency compared to that with beam, they have a possibility of having a vibration problem. The purpose of these experiments is to establish the way of evaluation of floor vibration, of floor vibration experiment and of design on a aspect of floor vibration. In this paper, we report the result of the analysis of damping constant at a point of design, and explain the damping constant at the natural frequency and about frequency characteristics of damping constants.