Abstract
This paper aims to develop an SI (structural identification) technique using the KEOT and the DMUM to decide on optimal location of sensors and to update FE model, respectively, which ultimately contributes to a composition of more effective SHM. Owing to the characteristic structural flexing behavior of cable bridges (e.g., cable-stayed bridges and suspension bridges), which makes them vulnerable to any vibration, systematic and continuous structural health monitoring (SHM) is pivotal for them. Since it is necessary to select optimal measurement locations with the fewest possible measurements and also to accurately assess the structural state of a bridge for the development of an effective SHM, an SI technique is as much important to accurately determine the modal parameters of the current structure based on the data optimally obtained. In this study, the kinetic energy optimization technique (KEOT) was utilized to determine the optimal measurement locations, while the direct matrix updating method (DMUM) was utilized for FE model updating. As a result of experiment, the required number of measurement locations derived from KEOT based on the target mode was reduced by approximately 80% compared to the initial number of measurement locations. Moreover, compared to the eigenvalue of the modal experiment, an improved FE model with a margin of error of less than 1% was derived from DMUM. Thus, the SI technique for cable-stayed bridges proposed in this study, which utilizes both KEOT and DMUM, is proven effective in minimizing the number of sensors while accurately determining the structural dynamic characteristics.
Highlights
During their service period, structures are exposed to gradual aging and to unspecified harmful environmental effects, such as earthquakes, strong winds, impacts, and structural instability due to external forces that can give rise to various structural defects
structural identification (SI) is defined as the process of defining a mathematical model of a given structure using measured physical information acquired from the actual target structure
Appropriate utilization of the SI technique allows for thorough structural health monitoring (SHM) of the target structure and reduces the amount of effort required for evaluation and maintenance of the structure and can contribute to ensuring structural safety
Summary
Structures are exposed to gradual aging and to unspecified harmful environmental effects, such as earthquakes, strong winds, impacts, and structural instability due to external forces that can give rise to various structural defects. FE models developed to resolve dynamic structural problems must effectively predict changes in modal parameters caused by alterations in design parameters In this regard, FE model improvement provides dynamic characteristics that conform to the target structure and can be utilized in the future as an objective and reasonable standard based on which aging and localized damage to a structure can be measured [19, 20]. In this study, experiments were conducted to evaluate SI techniques aimed at accurately determining the modal parameters of a target structure based on optimal measurement locations (i.e., minimum number of sensors), which are the required parameters for efficient and practical SHM. Regarding the derivation methods available for calculating changes in stiffness [ΔK] and mass [ΔM] due to structural changes, this study selected and applied DMUM considering its effectiveness in FE model improvement as well as its convenience and practicality for everyday use. The objective of FE model improvement is FE interpretation and modal experiment results, so the subscript A in each equation is the result value based on analysis and subscript X is the result value based on experimentation
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