PURPOSE: To damp a piping system by means of only a dynamic vibration reducer by dividing the piping system into pipe elements and coordinate transformation elements and performing mode analysis of each element.

CONSTITUTION: A piping model comprising a copper pipe 1 bent at 4 positions is fixed at both ends to a wall. In order to determine a oscillation mode shape by analyzing the vibration of the piping model by use of a transfer matrix method, the piping model is divided into 21 pipe elements 21-221, and 4 coordinate transformation elements 31-34. Each place where a maximum oscillation is generated in every mode from the oscillation mode shape at every resonance peak resulted from frequency response analysis is arranged in the setting place of a dynamic vibration reducer. Based on the equivalent mass of the place and equivalent load rate and so on, the items of the mass of the dynamic vibration reducer, load rate, damping coefficient and so on are determined, corresponding to which the dynamic vibration reducer designed for every mode is arranged in the setting place.