Multimode response factors for the seismic analysis of component-support systems

A common approach to the seismic response analysis of reactor component-support systems is to include the higher mode responses by applying a 'conservative' multimode factor to the fundamental mode response. The purpose of this investigation is to relax this conservatism, where appropriate, by developing multimode factors dependent on system parameters. Response factors are developed for several types of system configurations. It is shown that the current industry practice is conservative when multimode factors are properly used. (orig.)