Yilan Zhang, Moritz W. Häckell, Jerome Peter Lynch, Raimund Rolfes
|Titel:||Automated Modal Parameter Extraction and Statistical Analysis of the New Carquinez Bridge Response to Ambient Excitations|
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Modal characteristics including modal frequency, modal damping and mode shape are important structural parameters widely used in the design and analysis of structures. For example, modal parameters are valuable for calculating the dynamic response and capacity of a structure, updating finite element models and validating design assumptions. With the assistance of a vibration-based structural monitoring system, modal characteristics of an operational structure can be extracted in an autonomous fashion using output-only modal analysis techniques. If monitored over long periods of time, the modal properties of a structure can be tracked to determine how modal properties change as a function of other parameters such as environmental and load parameters. In this paper, modal parameters are autonomously extracted from one year?s worth of response data collected by the long-term structural monitoring system installed on the New Carquinez Bridge, a long-span suspension bridge constructed in 2003 in a seismic region of California. Two methods of parameter extraction are adopted using stochastic subspace identification: knowledge-based extraction and triangulation-based extraction. Statistical studies are performed on the extracted bridge modal parameters to quantify their distributions and to model their relationships with environment parameters.