Fundamental study on motion and deformation of building structures with soft stories from the viewpoint of wave propagation

This paper discusses the motion characteristics of building structures with soft stories integrated, from the wave propagation point of view. Even in dealing with a normal lumped mass system, if considering the energy transfer from a lumped mass to its next lumped mass, a very clear view can be given to the understanding of the mechanism for the vibration phenomena for these structures. In particular, the paper focuses on why a significantly large deformation occurs at the soft story in these structures. In addition, the relationship between the peak seismic deformation and energy flows in the structures subjected to large-period seismic excitation is quantitatively discussed from the standpoint of energy transfer induced by the wave propagation through the structures.