This paper presents a method to directly evaluate floor response spectra (FRS) from a specified ground response spectrum (GRS) without time history analysis. Seismic response of a secondary structure is decomposed into four parts. These components are combined based on a spectrum difference rule. As a reslut, the evaluation method is improved in terms of peak response at resonance in low damped buildings and FRS in high frequency range in damped buildings compared to previous studies. A practical evaluation method of the dynamic amplification factor at resonance is also presented. These methods are verified through time history analysis.

This paper discusses hysteretic tuned mass dampers (TMDs), which could passively be tuned according to the change of the degree of nonlinearity in steel buildings during earthquakes. Design properties for TMDs are composed of strength, stiffness and post-yielding stiffness. Optimal values for these properties are analyzed through stochastic analysis and closed forms of the optimal values are formulated. Finally, an estimation method for the peak displacement of buildings is proposed based on equivalent linearization techniques. The proposed method with hand calculation predicts quite accurate results compared to time history analysis.

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This paper describes the passive control method of mid-story isolation buildings designed to mitigate seismic response in the substructure. An equivalent two degree of freedom system consisting of both the substructure and the super structure is introduced.Optimal parameters of the isolation are formulated for the building subjected to white noise ground motions. The equivalent frequency and the damping factor of the equivalent single degree of freedom (SDOF) system are defined based on the random vibration theory. The practical estimation methods of maximum responses are proposed with the combination of the SDOF model and the response spectrum method. Finally, performance curve diagrams are presented.