Session: SE-09-01 Advanced Seismic Evaluation and Code (Joint session with C&S)

Paper Number: 152307

152307 - Numerical Simulation of Impact Vibration Caused by Spatial Gaps Between Piping and Piping Support in High-Temperature Piping Systems 

Abstract: 

In piping containing high-temperature fluid, a spatial gap, as it also is called gap clearance, is provided so that the piping support part can slide in the axial direction in order to release the thermal expansion of the piping. The piping system having this gap clearance becomes a structure with a "rattle", as hereinafter called gap structure. In the structures, an impact vibration occurs during forced vibration of large amplitude such as an earthquake, causing shock load and nonlinear vibration. Until now, the effect of gap on the structural strength and vibration characteristics provided in the piping support part has not been clarified. In this study, we proposed an analysis method to simulate impact vibrations of piping support parts faithfully to the laws of physics in order to clarify the effects. By approximating the impact phenomenon in the spring-mass system of the piping support, we developed an analysis method based on a model that could handle impact vibrations from moment to moment. The proposed method does not use a coefficient of restitution which considers only the physical state before and after the impact and does not take into account the time of the impact process. The proposed method, however, simulates the impact vibration from moment to moment and also takes into account the influence of the structural properties of the impacted object. The proposed method was a unique way unlike the traditional method since not using the restitution coefficient. With the method, it is possible to investigate the temporal changes in nonlinear response, shock load, and damping that occur depending on the magnitude of the spatial gaps. In this study, as described above, the dynamical model of the impact vibration was represented by a one-degree-of-freedom model consisting of spring and mass. In addition, a three-dimensional model was constructed in which piping was added as a beam model. By sequential integration using this model, it was possible to analyze the time history response of the vibrating piping impacting with the piping support. In this study, we showed that the proposed method could appropriately analyze the time history response of impact vibrations. Also, based on the analysis results, we discussed the influence of the magnitude of the spatial gaps on the seismic design of piping. As a result of the analysis, it was found that the vibration response changes depending on the magnitude of gap. As it increased, the boundary condition of the restraint disappeared and the vibration response changed. This change in vibrational response was remarkable in the resonance condition. It was also suggested that the higher harmonics were generated by the impact vibration.

Presenting Author: Akira Maekawa Osaka Sangyo University

Presenting Author Biography: Prof. Akira Maekawa was completed the master's program at Osaka Prefecture University in 1990 and got Ph.D. in 2007. He joined Kansai Electric Power Co., Ltd. in 1990 and consistently involved in the nuclear power generation business at Kansai Electric Power Co. Inc. After engaging in work such as seismic design and equipment maintenance, standards and standards, aging management, and nuclear power audits at power plants and research institutes, the Nuclear Power Business Division, and the Management Audit Office, he became a professor at the Department of Mechanical Engineering, Faculty of Engineering, Osaka Sangyo University in 2022.
Currently, in addition to being a professor at Osaka Sangyo University, Prof. Maekawa is a board member of the Japan Society of Earthquake Engineering and a member of the Osaka Prefectural Council for Maintenance and Management Technology of Urban Infrastructure Facilities.
His experts are vibration engineering, seismic engineering, maintenance engineering, codes & standards, and nuclear engineering.

Authors:

Akira Maekawa Osaka Sangyo University
Michiaki Suzuki Machine Craft Co., Ltd.