On the reliability of a PCA-based method for structural diagnosis in bridge structures with environmental disturbances

The basis for a vibration-based damage detection method is that changes in the constitutive properties of a structure will, in turn, modify its dynamic characteristics. Civil engineering structures are often subjected to time-varying environmental conditions and, as a consequence, the associated deviation of the identified structural features from the undamaged state may smear the changes caused by structural damages, thus causing non-issued alarms or false damage diagnoses. In order to assess their reliability for future in field applications, damage detection methods can be preliminarily validated by means of mechanical models in which the major changing environmental conditions are appropriately simulated. In doing so, two issues must be considered: the first is about the adopted thermomechanical model, the second deals with modeling realistic damage scenarios. To date, diagnostic tools are usually verified by means of oversimplified thermomechanical models, and the reliability of damage detection methods is demonstrated with reference to the damage severity only, whereas insufficient efforts have been directed toward the assessment of their effectiveness for the identification of space and time-varying damage scenarios. Through a refined three-dimensional thermomechanical model and a principal component analysis (PCA) diagnostic tool, this study addresses the feasibility of this specific class of damage detection methods for health monitoring of reinforced concrete bridge structures subject to realistic temperature effects. © Owned by the authors, published by EDP Sciences, 2012.