Structural health monitoring for layered structures using transmissibility functions

In this study, we proposed a structural health monitoring and diagnostic method for layered structures using the transmissibility function. This method belongs to the primary diagnosis one, and its purpose is to identify the location of abnormality quickly after abnormality detection. It focuses on the following fact. When the ceiling or foundation of the first floor is excited in the horizontal direction, the transmissibility function of the top floor is constructed with only the characteristics of the top floor, and in the case of descending to the lower floor, only the characteristics of the floor of interest are unknown parameters. In the diagnosis of an actual structure, there may be a difference between the actual vibration characteristics and those obtained from the mathematical model. We also proposed a method for predicting the resonance and peak frequencies in an abnormal condition based on the difference between the actual measurement and the mathematical model under a normal condition. First, we considered a three-layered structure as a numerical example and verified the validity of the proposed method. When the method was applied to the three types of abnormal conditions, it was shown that the abnormal diagnosis could be performed correctly. Next, we constructed an experimental model of a three-layered structure, and verified the applicability of the proposed method. We realized three types of abnormal states similar to the numerical examples and showed that correct abnormal diagnosis was possible. As described above, the validity and applicability of the proposed method were clarified.