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Alessandra Achilli,Giacomo Bernagozzi,Raimondo Betti,Pier Paolo Diotallevi,Luca Landi,Said Quqa,Eleonora M. Tronci 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.2
This paper proposes a novel method suitable for vibration-based damage identification of civil structures and infrastructures under ambient excitation. The damage-sensitive feature employed in the presented algorithm consists of a vector of multivariate autoregressive parameters estimated from the vibration responses collected at different locations of the analyzed structure. Outlier analysis and statistical pattern recognition are exploited for damage detection and localization. In particular, the Mahalanobis distance between a set of reference (i.e., “healthy”) and inspection parameters is evaluated. A threshold is then selected to determine whether the inspection vectors refer to damaged or undamaged conditions. The effectiveness of the proposed approach is proved using numerical simulations and experimental data from a benchmark test. The analysis results show that the largest values of Mahalanobis distance can be found in the proximity of those sensors closest to the damaged elements. Thus, the Mahalanobis distance applied to vectors of multivariate autoregressive parameters has proven to be a robust indicator for damage detection and localization.
Balsamo, Luciana,Mukhopadhyay, Suparno,Betti, Raimondo Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.3
A modal parameter based damage sensitive feature (DSF) is defined to mimic the relative change in any diagonal element of the stiffness matrix of a model of a structure. The damage assessment is performed in a statistical pattern recognition framework using empirical complementary cumulative distribution functions (ECCDFs) of the DSFs extracted from measured operational vibration response data. Methods are discussed to perform probabilistic structural health assessment with respect to the following questions: (a) "Is there a change in the current state of the structure compared to the baseline state?", (b) "Does the change indicate a localized stiffness reduction or increase?", with the latter representing a situation of retrofitting operations, and (c) "What is the severity of the change in a probabilistic sense?". To identify a range of normal structural variations due to environmental and operational conditions, lower and upper bound ECCDFs are used to define the baseline structural state. Such an approach attempts to decouple "non-damage" related variations from damage induced changes, and account for the unknown environmental/operational conditions of the current state. The damage assessment procedure is discussed using numerical simulations of ambient vibration testing of a bridge deck system, as well as shake table experimental data from a 4-story steel frame.
Luciana Balsamo,Suparno Mukhopadhyay,Raimondo Betti 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.3
A modal parameter based damage sensitive feature (DSF) is defined to mimic the relativechange in any diagonal element of the stiffness matrix of a model of a structure. The damage assessment isperformed in a statistical pattern recognition framework using empirical complementary cumulativedistribution functions (ECCDFs) of the DSFs extracted from measured operational vibration response data. Methods are discussed to perform probabilistic structural health assessment with respect to the followingquestions: (a) “Is there a change in the current state of the structure compared to the baseline state?”, (b)“Does the change indicate a localized stiffness reduction or increase?”, with the latter representing asituation of retrofitting operations, and (c) “What is the severity of the change in a probabilistic sense?”. Toidentify a range of normal structural variations due to environmental and operational conditions, lower andupper bound ECCDFs are used to define the baseline structural state. Such an approach attempts to decouple“non-damage” related variations from damage induced changes, and account for the unknownenvironmental/operational conditions of the current state. The damage assessment procedure is discussedusing numerical simulations of ambient vibration testing of a bridge deck system, as well as shake tableexperimental data from a 4-story steel frame.