Ayman Saudy

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Civil Engineering and Engineering Mechanics


A. Ghobarah


T. S. Aziz


The decoupled seismic analysis of Multi-Degree-Of-Freedom (MDOF) secondary system subjected to multiple-support excitations overestimates its response. It is recognized that the analysis overestimates the secondary system response because the dynamic characteristics of the combined Primary-Secondary (P-S) system are neglected. The problem that is addressed in this thesis is how to include the effects of these dynamic characteristics in decoupled seismic analyses of multiply-supported MDOF secondary systems. The objective is to estimate the secondary system response using a decoupled seismic analysis such that it approximates the response that would have been obtained using a coupled analysis. Three approaches are considered in addressing the problem. These are the conventional deterministic approach, the recently developed Cross-Cross-Floor-Spectrum (CCFS) approach, and the stochastic approach. Three major contributions are achieved. First, the complexity associated with the seismic analysis of multiply-supported MDOF secondary systems is highlighted. Second, an improved CCFS approach, that avoids the shortcomings of the original CCFS approach, is proposed. Third, a new stochastic approach, that accounts for the dynamic characteristics of the combined P-S system, is developed.

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