New Developments in Seismic Analysis of Primary and Secondary Systems

by Ajaya Gupta, North Carolina State Univ at, Raleigh, Raleigh, NC, USA,

Document Type: Proceeding Paper

Part of: Structural Engineering in Nuclear Facilities


This paper presents recent advances made at NCSU in the seismic analysis of these systems. Algorithms are presented by which coupled mode shapes and frequencies can be evaluated without performing a new eigenvalue solution, given the mode shapes and frequencies of the decoupled models. Simple and accurate equations are presented to predict changes in frequencies and responses. With the coupled mode shapes and frequencies, one can obtain any primary or secondary response directly from the input spectrum. Alternatively, one can develop instructure spectra at various locations in the primary system accounting for the primary-secondary system interaction. Correlation between the support motions is also generated. Equations are presented for evaluating complex mode shapes and frequencies of coupled systems when due to unequal damping values of primary and secondary systems, the coupled system becomes nonproportionally damped. Recent progress, in case of tuned systems is also reported.

Subject Headings: Coupling | System analysis | Damping | Algorithms | Eigenvalues | Correlation | Nuclear power | Power plants

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