Theoretical analysis and experimental study on the dynamic behavior of a valve pipeline system during an earthquake

To study the dynamic behavior of pipeline systems installed with large-mass valves within nuclear power plants during earthquakes, seismic simulation tests are carried out on a pipeline system equipped with a DN80 gate valve,and the FEM updating technique is used to identify the stiffness distribution of the valve. By conducting tests and a numerical analysis, the following conclusions are obtained: After a large-mass valve is installed in the pipeline, the system shows higher sensitivity to intermediate and high frequency components in the earthquake than low frequency components. It is possible for the intermediate frequency components to be amplified by the valve in the horizontal direction, while the pipes tend to amplify the high frequency components in horizontal and vertical directions. Changes in the high-order modes of the system depend on valve stiffness distribution. Since the existence of a valve makes pipeline system damping distribute with an obvious non-proportional feature, when the response spectrum method is used to calculate the response of the pipeline system, it could result in an underestimation of low-damping positions and overestimation of high-damping positions.