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Studies On Optimal Design Of Measurement Point Layout For Structural Health Monitoring

Posted on:2012-04-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:J ZhaoFull Text:PDF
GTID:1118330335964530Subject:Engineering Mechanics
Abstract/Summary:PDF Full Text Request
Structural health monitoring system is an important means to protect the safety of the large structures, whereas optimal sensor placement is the key technology of structural health monitoring. In view of the engineering environmental factors, economic factors, risk assessment and other factors, the most limited measurement point is required to satisfy the demand for structural health monitoring, so the optimal design of measurement point layout is of important engineering value and social significance. In this paper, different measurement point layout methods are systematically studied in depth by numerical simulation, test analysis and engineering cases. The main contents of this dissertation are described as follows:1. Optimal measurement point layout method will be broadly divided into four parts through the analysis and summary of the current measurement point layout method research:optimal measurement point layout method based on risk assessment, optimal measurement point layout method based on static test, optimal measurement point layout based on moving load and optimal sensor placement method based on dynamic test, covering the most existing methods in all research. The initial theoretical framework for measurement point layout of structural health monitoring is established, and some methods are studied in-depth in order to achieve more valuable results.2. Starting from the basic theory of risk assessment, the paper draws forth the important role of the dynamic management system in the actual project. Whereas the optimal design of measurement point layout is the key part of the whole system, which plays a decisive role in the whole system. Based on risk assessment, the paper discusses the intrinsic link between risk assessment and the optimal design of measurement point layout, proposes measurement point layout methods based on risk-based Engineering major source. Combined with the author's experience and the results of monitoring of thirty actual foundation pit engineerings in recent years, the paper verifies the practicality and effectiveness of the methods, and summarizes the corresponding criterion, which makes up the existing norms and could be used to guide the actual construction effectively, and it also applies to the structural health monitoring of bridges, dams and other structures.3. The author advances the regional gradient method based on static structural deformation and the "step test " method based on static structural damage identification for measurement point layout, which can approximate the actual deformation of the structure and identify the location of damage elements effectively from the numerical simulation of beam and plate structure, which is a gradual process from the approximation to the true deformation and from the potential damaged area gradually to the real damaged cell. The effectiveness of the two methods are confirmed under limited measurement points based on static test.4. The objective is to show the potential of the crack detection method based on Multi-resolution Analysis of Wavelet, which depends on the response at a single point on a beam subject to concentrated moving loads. When moving along the structure, the moving loads cause small distortions in the dynamic response of the beam at the crack locations. In general, these small distortions are difficult to detect visually. An ANSYS model of a cracked beam is established. The moving load is transient analyzed by shifting the point of the concentrated force. The response at mid-span of the beam is calculated and Wavelet Multi-resolution transformed. The crack on the beam can be found by the position of the peak of Wavelet Multi-Resolution Analysis. The method can also be used in the continuous cracked beam. Furthermore, structural deflection, impact factor and damage sensitivity are studied on different measurement points layout program under a moving load, the basic principles of measurement point layout are summed up.5. Effective independence method (EFI) and effective independence driving-point residue method(EFI-DPR) are adopted to determine optimal design of measurement point layout for dynamic test of the beam and arch structure. By comparing with the traditional equal divided method (ED), numerical and experimental research has been done to determine the effective method and reasonable scheme for measurement point layout. Firstly, modal analysis of the beam and arch structure are simulated by the finite element software ANSYS, and three different measurement point layout methods have been applied. Then, minimum of the mean square error criteria and the modal assurance criterion are employed to assess the suitability of the chosen methods. Finally, the optimal design scheme of measurement point layout is presented based on the real beam and arch modal experiment.
Keywords/Search Tags:The optimal design of measurement point layout, Structure monitoring system, Modal Analysis, Risk assessment, Moving load, Multi-resolution Analysis of Wavelet
PDF Full Text Request
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