Eigen-properties of a building during five earthquakes

摘要

This paper is concerned with the realization of finite dimensional, linear, time-invariant models for a 4-story building from multiple data sets. The building, located on the University of California at Irvine campus, is instrumented with an accelerometer network of forty-three channels. Five data sets, recorded during five earthquake events, are used for the realization and validation of the models. The objective of this paper is to investigate and discuss the intrinsic differences and similarities in the dynamic response of the building during the five earthquakes. To this end, the time domain subspace system realization algorithms are employed to build state space models for the building from input (excitation) and output (response) measurements. Each model accurately replicates the building dynamic response for the earthquake from which it is constituted. The models are then successfully used to extract the eigenfrequencies, eigenvectors, and associated damping ratios of the vibration modes of the building. The five state space models derived have different eigen-properties;;eigenfrequencies, eigenvectors, and associated damping ratios;;during the five earthquakes of different amplitudes. However, taken cumulatively the five individual models give an insight into the extent and type of amplitude dependent response. The state space models identified suggest that the response of the building is amplitude dependent with response frequency and damping, being dependent on the response amplitude.