This study is concerned with the response spectra analysis of the secondary structures including the correlations effect between multisupport motions. Secondary subsystems installed inside of a primary structure, are frequently subjected to nonuniform support excitations. Based on the random vibration theory, the floor response spectra and the correlation coefficients of the floor motions are derived from the design ground response spectra.
Example analysis are carried out for various primary-secondary systems. The validity of the proposed method is examined by checking the results with those obtained by other methods, such as the conventional response spectrum method without including the correlation of support motions, the random vibration method, and the time history analysis method. The results show that the proposed method yields more accurate results than those by the conventional response spectrum analysis method without the correlation effects of the support motions.