Structural health monitoring of layered structure by strain measurements

Abstract

Structural health monitoring (SHM) of building structures is a very important technology in the effort to realize a sustainable society. Various studies on SHM have been carried out, and it is effective because it avoids accidents and predicts behaviour of structures. In this study, we proposed a method of SHM for a layered structure, in which the abnormal layer of the structure was identified by strain measurement. The main point of the study is that rotational degrees of freedom are constrained at both ends of the wall, so that the wall of each layer vibrates individually. First, in the normal condition, a location where the strain is almost zero on the outer wall of each layer is specified, and the strain at that point is constantly measured. Then, when an abnormality occurs in a certain layer, a significant value of strain appears in the abnormal layer where the strain is originally zero. We verify the proposed method by numerical simulation. We consider a three-layered structure, modelled as a cantilever beam. Abnormality is assumed to be the decrement of stiffness at a certain element, and it was shown that the effect of abnormality appeared throughout the structure in the natural vibration mode while it appeared locally in the strain measurement. The random response was then calculated by numerical integration, and the layer where the abnormality occurred could be identified by using the proposed method. Finally, we checked the applicability of the proposed method by experiment. As a result, it was shown that the method was possible to identify the layer where an abnormality occurred as well as numerical simulation.

Structural health monitoring for layered structure using a force identification approach

“…Research has also been conducted to monitor the condition of a structure by converting vibration data measured at many points in the structure into big data (Watabe and Omori, 2015). We previously proposed a method to identify the precise locations of abnormalities occurring in layered structures at the outer wall or at the joint between the outer wall and floor (Kawamura et al, 2019). The method's main feature is that the rotational degree of freedom (DOF) of the outer wall is constrained on the floor surface, so the property changes due to abnormalities occurring in a certain layer are localized to that layer and not transmitted to other layers.…”

“…We propose three types of diagnosis method in which the measurement data and the excitation method for diagnosis are different. In the first method (Kawamura et al, 2019), the strain data of every wall against any excitation method are used. In the second method (Kawamura et al, 2022), the response data of every layer against the ground or the first layer excitation are used.…”

Structural health monitoring for layered structures using transmissibility functions

“…Recently, research has been conducted to monitor the condition of a structure by converting vibration data measured at many points in the structure into big data (Watabe and Omori, 2015). We previously proposed a method to identify the precise locations of abnormalities occurring in layered structures at the outer wall, or at the joint between the outer wall and floor (Kawamura et al, 2019). The main feature of this method is that the rotational degree of freedom (DOF) of the structure, Resonance and peak frequencies Shozo KAWAMURA*, Takenori YAMAGUCHI*, Masami MATSUBARA* and Daiki TAJIRI* outer wall is constrained on the floor surface, so the property changes due to abnormalities occurring in a certain layer are localized to that layer and not transmitted to other layers.…”