Abstract
Piping leakage can occur at T-joint, elbows, valves, or nozzles in nuclear power plants and nonnuclear power plants such as petrochemical plants when subjected to extreme loads and such leakage of piping systems can also lead to fire or explosion. For example, leakage of sodium, toxic gases, or nitrogen in hospitals can cause man-made hazards. The primary objective of this research is to understand the vibration effects due to classical/nonclassical damping with building-piping systems under extreme loads. The current evaluation employed finite-element analysis to calculate the effects of the responses of classically and nonclassically damped building-piping systems. Classical and nonclassical damping matrices for a coupled primary-secondary system were developed based on the Rayleigh equation. A total of 10 selected ground motions were applied to single degree of freedom (SDOF) primary-SDOF secondary (2-DOF coupled) systems in which the ratios of the natural frequencies between the primary and secondary systems ranged between 0.9 and 1.1. It revealed that the vibration effect of nonclassical damping was significant where the natural frequencies of the two systems were nearly tuned. For piping-material nonlinearity, the effects of nonclassical damping on the result forces of piping systems were not significantly different from those of classical damping.
Highlights
The vibration of a piping system is significantly influenced by the building in which it is installed, owing to the fact that, typically for such systems, the secondary structure is coupled with the primary structure
Finite-element building-piping models derived from the Open System for Earthquake Engineering Simulation (OpenSees) [14] were used to carry out the Rayleigh equation to develop classical and nonclassical damping matrices for a 2-degree of freedom (DOF) coupled primary-secondary system
The present study evaluated the effects of the seismic responses of classically and nonclassically damped coupled primary-secondary piping systems, including nonlinearity behavior
Summary
The vibration of a piping system is significantly influenced by the building in which it is installed, owing to the fact that, typically for such systems, the secondary structure is coupled with the primary structure. In recent years, many researchers have recognized the need to control the excessive behavior under seismic ground motions, in order to reduce the seismic damage or system drift of structural and nonstructural components [8,9,10,11,12,13]. This paper reports the results of an evaluation of the vibrations of classical and nonclassical damping for coupled primary-secondary systems including material nonlinearity. Finite-element building-piping models derived from the Open System for Earthquake Engineering Simulation (OpenSees) [14] were used to carry out the Rayleigh equation to develop classical and nonclassical damping matrices for a 2-DOF coupled primary-secondary system. The effect of the mass ratio between building and piping systems was studied
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