Transfer-Function-Based Criteria for Decoupling of Secondary Systems


New criteria for decoupling of primary-secondary systems have been recently proposed by the first writer. They are defined by a limited variation of the maximum transfer function of a secondary system that is connected to a single-degree-of-freedom primary-secondary system. In this paper, their sufficiency for decoupling is investigated when the two-degree-of-freedom primary-secondary system is subjected to a filtered white noise process of the Kanai-Tajimi power spectrum. Verifications for sufficiency of the new criteria are extended to a secondary system mounted to a multi-degree-of-freedom primary system. Effects of site condition on the criteria are also studied, by varying the characteristic frequency of the Kanai-Tajimi spectrum. The upper-bound mass ratios resulting from the criteria, above which a coupled analysis is required, are compared with the current decoupling criteria mainly used in the design of nuclear facilities. Revisions of the current decoupling criteria are suggested as a result of this study. A simple procedure is recommended and illustrated by an example to apply the new criteria into the analysis and design of secondary systems.


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Degrees Of Freedom (Mechanics); Spectrum Analysis; Transfer Functions; White Noise; Kanai-Tajimi Power Spectrum; Dynamics

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 1999 American Society of Civil Engineers (ASCE), All rights reserved.

Publication Date

01 Mar 1999