Substructuring Techniques in the Time Domain for Primary-Secondary Structural Systems

Keywords: Substructure Methods, Seismic Performance, Secondary-System Response, Secondary Substructure, Numerical Simulation, Modal Condensation, and Primary Substructure.

Abstract: The question of how a primary structural system is affected by the presence of secondary structural and/or non-structural attachments and vice-versa during an intense dynamic event such as an earthquake can best be answered by recourse to numerical simulation coupled with experimental verification. Toward this goal, the present work develops a substructuring methodology in the time domain for the analysis of structures containing secondary systems. The present methodology allows for a separate analysis of the primary and secondary substructures under the influence of the applied loads. The interaction forces responsible for their coupling are also evaluated. The size of both primary and secondary subsystem representations can be reduced by introducing modal condensation via Ritz vectors that do not form complete modal sets. A three-story shear building containing a two degree-of-freedom secondary system is carefully analyzed with and without modal condensation. Parametric studies are conducted by changing the properties of the secondary substructure and by considering different types of applied loads in the form of ground excitations.