Normalized input–output minimization analysis of wave propagation in buildings

In previous studies on the earthquake response of buildings, vibration approaches were used more often than wave propagation approaches; thus, wave propagation through a building has not been sufficiently investigated. This paper presents a wave propagation modeling analysis of strong motion records for actual buildings in comparison with an analysis of those in elastic soil media and in analytical building models. We use the normalized input–output minimization (NIOM) method, which can model wave propagation in multiple linear systems by considering the statistical correlation among the strong motions at different observation locations. Output wave models simplified by the NIOM method show two clear peaks that correspond to incident and reflected waves propagating through the building in the vertical direction. Obtained wave propagation properties, such as wave travel time and wave amplitude ratio, at each story of the building are found to reflect the structural properties like rigidity and damping at that story. Thus, the NIOM method is shown to be an effective new method of investigating structural behavior of buildings during earthquakes.