A comparison of some methods for structural damage detection

In principal, a proper analysis of the dynamic response of a structure can provide general indicators of its operational conditions. When the dynamic response changes due to variations of the physical properties of a structure, then one may conclude that some kind of damage has occurred. This paper presents an investigation of the robustness and comparison of four simple methodologies to both identify and quantify the damages in structures, based on the use of Frequency Response Functions (FRF) signals, Principal Component Analysis technique (PCA), and transmissibility. A steel beam with constant rectangular cross-section is used to compare the proposed approaches. At rst, nine damaged scenarios are created, for each of which numerical examples are discussed; a database of FRFs is measured using modal testing. Then, PCA theory is applied to the FRF matrix, and global damage detection and quantication indices are dened using the rst three principal components; Hotellingʹs T-squared distribution is also applied, and two other indicators, transmissibility damage indicator and weighted damage indicator, are computed for the assessment of damage using transmissibility. The reported examples show that all proposed methods are able to detect and quantify damages at the initial stage.