Dynamic analysis of inelastic primary–secondary systems

Two methods are proposed to compute the response of inelastic composite primary–secondary systems by a decomposition into undamped substructure modes. The first method is based on an iterative syntheses, where interface conditions as well as inelastic deformations of the substructures are treated as additional fictious loadings and their intensities are calculated in an iterative process. Alternatively, only modal coupling of tuned modes is considered, thus, restricting the application to coupled systems with a modal secondary to primary mass ratio much smaller than one. The dynamic behavior of oscillators attached to frames with various inelastic substructure properties is investigated, which are excited by the north–south component of the El Centro earthquake sample. Results derived by the proposed methods are compared to decoupled analyses to estimate their capability with respect to inelastic substructural behavior and non-classical damping.