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Removal of masking effect for damage detection of structures

Wah, William Soo Lon; Owen, John S.; Chen, Yung-Tsang; Elamin, Ahmed; Roberts, Gethin Wyn


William Soo Lon Wah

Yung-Tsang Chen

Ahmed Elamin

Gethin Wyn Roberts


Damage detection of civil engineering structures relies heavily on the use of outlier analysis/novelty detection analysis. Generally, data captured from a structure in its normal environmental condition are used to create a model and compute control limits to represent the normal range of variations of damage sensitive features of the structure. However, the training database used usually includes outlier measurements, which may introduce masking effect. These outlier measurements can affect the mean and standard deviation/covariance matrix of the training database, and hence, affect the model and the control limits. As a result, small damage may not be detected. Therefore, this paper proposes an approach of selecting a `clean' training database for the construction of the baseline of the undamaged structure so as to detect damage at an earlier stage. The approach makes use of Principal Component Analysis and Median Absolute Deviation to identify outlier measurements. This approach can be applied before the application of damage detection methods to allow damage to be detected at an earlier stage. The proposed approach is applied to a numerical beam model and the Z24 Bridge, in Switzerland. The results obtained demonstrate that damage can be detected at an earlier stage using the approach proposed in this paper. The proposed method also allows the determination of the model (e.g. linear or nonlinear) to be used for damage detection.


Wah, W. S. L., Owen, J. S., Chen, Y., Elamin, A., & Roberts, G. W. (2019). Removal of masking effect for damage detection of structures. Engineering Structures, 183, 646-661.

Journal Article Type Article
Acceptance Date Jan 1, 2019
Online Publication Date Jan 18, 2019
Publication Date Mar 15, 2019
Deposit Date Jan 7, 2019
Publicly Available Date Jan 19, 2020
Journal Engineering Structures
Print ISSN 0141-0296
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 183
Pages 646-661
Keywords Civil and Structural Engineering
Public URL
Publisher URL
Additional Information This article is maintained by: Elsevier; Article Title: Removal of masking effect for damage detection of structures; Journal Title: Engineering Structures; CrossRef DOI link to publisher maintained version:; Content Type: article; Copyright: © 2019 Elsevier Ltd. All rights reserved.


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