Abstract
Dynamic characteristics of buildings are key issues in the seismic design technology. From this point of view, Building Research Institute is operating the strong motion network for buildings since 1957. In this paper, dynamic characteristics of actual buildings are estimated using acceleration records of the BRI strong motion network. For an instance, the transition of natural periods and damping ratios of the slightly damaged buildings by an earthquake are examined using the moving time window technique. The change of dynamic characteristics depending on displacement amplitude can be verified. Relation among natural periods, damping ratios and building heights is also discussed.