Numerical Study on Inelastic Seismic Design of Piping Systems Using Damping Effect Based on Elastic–Plastic Property of Pipe Supports

Abstract

This study describes inelastic seismic design of piping systems considering the damping effect caused by elastic–plastic property of a pipe support which is called an elastic–plastic support. Though the elastic–plastic support is proposed as inelastic seismic design framework in the Japan Electric Association code for the seismic design of nuclear power plants (JEAC4601), the seismic responses of the various piping systems with the support are unclear. In this study, the damping coefficient of a piping system is focused on, and the relation between seismic response of the piping system and elastic–plastic behavior of the elastic–plastic support was investigated using nonlinear time history analysis and complex eigenvalue analysis. The analysis results showed that the maximum seismic response acceleration of the piping system decreased largely in the area surrounded by pipe elbows including the elastic–plastic support which allowed plastic deformation. The modal damping coefficient increased a maximum of about sevenfold. Furthermore, the amount of the initial stiffness of the elastic–plastic support made a difference in the increasing tendency of the modal damping coefficient. From the viewpoint of the support model in the inelastic seismic design, the reduction behavior for the seismic response of the piping system was little affected by the 10% variation of the secondary stiffness. These results demonstrated the elastic–plastic support is a useful inelastic seismic design of piping systems on the conditions where the design seismic load is exceeded extremely.

Seismic performance of an industrial multi-storey frame structure with process equipment subjected to shake table testing

“…Moreover, Bursi et al (26) showed that a typical petrochemical piping system coupled with a steel support structure is endowed with a limited q factor, because both pipes and the support floors cannot ensure a rigid floor behavior and a great involvement of dissipative elements. In addition, (27) and (28) demonstrated that the response of a piping system can be greatly reduced by including the nonlinear behaviour of local supports.…”

Reliability Analysis of a Pre-Cracked Structure in Accidental Operation Conditions

“…The studies on the PFM are applied to the assessment of structural reliability of pressurized vessels of a nuclear power plant [1][2][3][4][5][6][7][8][9]. Nowadays, the PFM takes an important part in safety design of the nuclear power plant [10][11][12][13][14]. In the PFM analysis, the crack size, material strength, crack growth rate, etc.…”