Studying the damping characteristics of the system of building and infrastructure considering the Soil-Structure Interaction

This paper studies the damping characteristics of the soil foundation under a building concerning the Soil-Structure Interaction (SSI). By considering a multi-story building resting on a piled raft foundation as a typical SSI system, subjected to an earthquake (i.e., Chi Chi earthquake, Taiwan 1999), the time-dependent responses of specified locations in the foundation are recorded and analyzed, both in-time domain and frequency domain. Referring to prior knowledge about system identification and damping, this study suggests an overwhelming approach to determining the damping ratio for analyzing more thoroughly a system of SSI systems. Results are a general procedure to establish the damping matrix, namely the Caughey damping matrix which takes several frequencies into account. A different viewpoint that the connection of superstructure and infrastructure in series could help to estimate the damping, and contribute to a wide range of system identification. All these procedures are used to predict more properly the damping characteristics of a system of structures. Suggestions over the findings would be expected to contribute a more rigorous component to the analysis of high-rise buildings in the future.