357 充填物を有するフレキシブルニ重配管の振動減衰性能評価

Abstract

It is well known in the fields of nuclear and chemical plants that various pipes conveying liquids and gasses should be safe and reliable against excitation by earthquakes. This study proposes an effective use of the flexible pipe system, consisting of a double-walled pipes and infilling materials, to increase the bending rigidities and robustness to excitation. In particular, the vibration properties of such double-walled flexible pipe are examined in terms of changes of infilling rates. Aluminum pipes and glass beads are employed in the experiment to assemble the flexible pipe, and the natural frequencies and damping ratios are measured by using an experimental modal analysis technique with an impulse hammer. The present double-walled pipe system with beads successfully results in higher damping ratios than the pipe without beads. To reveal further relationship between infilling rates and damping ratios, experiments for the single-walled pipe with different filling rates are also conducted. It becomes then clear that there is a moderate filling rate to improve the damping properties of the flexible pipe.