Comparison of indicators of damage location based on information gain

Vibration-based methods for damage localizations are often based on a damage feature defined in terms of changes of modal or operational shapes. These methods allow detecting variations of the damage feature that can be attributed to damage. Many of these methods are based on the detection of irregularities in the modal shapes of the structure. In this paper, the performance of several algorithms for damage localization is investigated and the results are compared both qualitatively, in terms of the capability to correctly localize damage, and quantitatively, in terms of relative information entropy. This parameter quantifies the gain of information obtained a given damage indicators with respect to a reference one. As reference damage indicator is assumed the prior probability of damage defined in terms of expert opinion or as a non-informative parameter. The investigation is carried out using responses simulated using the calibrated finite element model of a real Italian bridge permanently monitored by the Italian Seismic Observatory of Structures.