Damping evaluation using full-scale data of buildings in Japan

Full-scale data on damping of buildings in Japan have been collected by the Damping Evaluation Committee of the Architectural Institute of Japan. Reliable data on 137 steel-framed buildings, 25 reinforced concrete (RC) buildings, 43 steel-framed reinforced concrete (SRC) buildings have been compiled in a database. Most of these data have been evaluated from vibration tests in a small amplitude region. This paper describes damping ratio characteristics of steel-framed buildings and RC/SRC buildings based on analyses of the database, including effects of several building factors. It is shown that the higher the building, the smaller the first-mode damping ratio. Furthermore, the damping ratios seem to be affected by building use: Those of hotels and apartments are generally larger than those of other buildings. However, damping ratios are more widely scattered than natural periods, because they are also affected by vibration amplitude, foundation type, and so on. Frequency and amplitude dependencies of damping ratios are also examined, and predictors of damping ratios with their dependencies are proposed.