Modal methods in the dynamics of multiply coupled primary-secondary systems

A unified formulation for seismic analysis of multiply connected primary-secondary systems was proposed. At first, in order to avoid numerical accuracy problems deriving from differences in mass, damping and stiffness properties of the two subsystems the component-mode synthesis approach was used. Coupling, non-classical damping and dynamic interaction were included in the analysis using a combined analytical model and considering the exact complex-valued eigenproperties. Then, three different methods for the coupled seismic analysis in time domain were described in detail. In the realistic hypothesis of undercritically damped mode-shapes a unified formulation of seismic response was finally obtained whatever method was used