A Robust PCA-Based Framework for Long-Term Condition Monitoring of Civil Infrastructures
- Publisher:
- Springer International Publishing
- Publication Type:
- Chapter
- Citation:
- Data Science in Engineering, Volume 9, 2022, pp. 79-85
- Issue Date:
- 2022-01-01
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This chapter proposes an output-only method for condition monitoring of civil infrastructures through studying a couple of lowest structural natural frequency signals. The main challenge in this sort of problem is to mitigate the effect of the Environmental and Operational Variations (EOV) on the structural natural frequencies to avoid misinterpretation of these effects as damage. To this end, a robust Principal Component Analysis (PCA)-based approach is proposed that uses a couple of lowest structural natural frequency signals obtained from vibration data over a long period of time. First, the proposed method utilizes a truncated transformation matrix of the robust local PCA of a portion of the dataset corresponding to the healthy state of the structure to remove the EOV effects by mapping the dataset to a new space. The difference between the mapped signals and the original signals is deemed to minimize the effect of the EOV. As such, extracting the mapped data from the original data, termed error signals, will remove the EOV effects and can be further used for damage detection. To this end, the Mahalanobis distances of the errors in the test set from the distribution of the errors in the baseline data are used for condition monitoring through constructing a Hotelling (T2) control chart. The proposed PCA-based method does not apply the covariance matrix and the mean vector of the entire dataset, but instead the Minimum Covariance Determinant (MCD) algorithm, in its fast mode (FastMCD), is employed to obtain a robust covariance matrix and mean vector of the dataset. It is shown through solving the benchmark problem of the Z24 bridge that the proposed method can effectively increase the accuracy of the damage detection compared with the case when the normal PCA is used.
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