Development and evaluation of methods for coupled seismic analysis of piping systems.

摘要

A common method of calculating the response of a secondary system (equipment, piping, HVAC, etc.) connected to a primary system (building) is the instructure response spectrum (IRS) method. An IRS is a curve of the maximum responses of a series of single-degree-of-freedom (SDOF) oscillators with varying frequencies attached to an instructure location on the primary system.;Closed-form equations are developed to calculate the response of SDOF secondary systems connected to multi-degree-of-freedom (MDOF) primary systems accounting for dynamic mass interaction and non-classical damping. The eigenproperties and response values of the coupled system are given by closed-form equations. Formulas are derived separately for tuned or nearly tuned and detuned conditions and matching is performed to obtain equations for all conditions ranging from tuned to detuned. Instructure response spectra obtained from these closed-form equations are shown to be in good agreement with those from a more rigorous IRS method (computer program, CREST-IRS). Response of MDOF secondary systems multiply connected to MDOF primary systems is calculated using the IRS values obtained from the closed-form equations by a computationally efficient approach. The response values calculated from the closed-form equations and those from the computer program CREST-IRS are shown to be in good agreement.;A computational algorithm is developed to perform dynamic finite element analysis of coupled non-classically damped primary-secondary systems. The program is used to establish the accuracy of the results obtained from the closed-form equations and from the computer programs CREST and CREST-IRS.