Seismic response of tuned single degree of freedom secondary systems Original Research Article

Modal synthesis procedure for evaluating spectral acceleration in the single degree of freedom (SDOF) secondary system oscillator is studied. Problems encountered in the evaluation of response for secondary oscillators that are tuned or nearly tuned with the primary system modes are discussed and solutions to these problems are presented. A new hybrid approach is proposed that gives accurate spectral acceleration in tuned secondary systems for both cases of zero and non zero mass ratio in structures that are nonclassically damped. Formulations are developed to evaluate the interaction-free (zero mass ratio) instructure spectral accelerations for perfectly tuned secondary oscillators in a coupled primary-secondary system when the two uncoupled systems have same damping characteristics (classical damping case).