Simulation methods for seismic behaviour of buildings in unbounded soil media with radiation damping

Mathematical and computer methods have been used by others to predict the seismic behaviour of viscous damped structures, yet most analyses have not accounted for the influence of an unbounded foundation. In order to better understand the motional behaviour of structures during earthquakes, this study considers the effects of radiation damping and flexibility when characterizing the interaction between damped structures and unbounded soil media. Two numerical methods, the consistent-infinitesimal finite element cell method and a new quiet boundary method, are introduced here. Also, computer simulation is used to demonstrate the effects of radiation damping for far field, unbounded media. The differences in seismic responses of structures with and without consideration of radiation damping are significant. The results also make clear the importance of accounting for such effects when, for example, structural engineers incorporate structural control devices into their designs.