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Structural Health Monitoring Considering Nonlinear Behavior of Structures Using the Sensitivity of Time-Varying Modal Parameters

Hosseini, Anahita Sadat | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52915 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. The process of implementing a damage detection strategy for aerospace, civil and mechanical engineering infrastructure is referred to as Structural Health Monitoring (SHM). Many portions of our technical infrastructure are approaching or exceeding their initial design life. As a result of economic issues, these civil, mechanical and aerospace structures are being used in spite of aging and the associated damage accumulation. Therefore, the ability to monitor the health of these structures is becoming increasingly important. In many cases, damage causes a structure that initially behaves in a predominantly linear manner to exhibit nonlinear response when subject to its operating environment. The formation of cracks that subsequently open and close under operating loads is an example of such damage. In this study, an attempt is made to propose a practical method for nonlinear damage detection of structure using the sensitivity of time-varying modal parameters. The nonlinearity is defined in the model by assigning Bouc-Wen hysteretic material behavior to certain elements. This model have been simulated in MATLAB program. Particle swarm optimization algorithm is also used to obtain the Bouc-Wen hysteresis parameters. In this study, an improved sensitivity equation have been employed in the process of updating the finite element model to estimate mode shape changes by parametrizing stiffness matrix of a building as a decomposition in to a matrix of singular values and singular vectors considering nonlinear behavior of a structure. This technique needs fewer mode shapes to be measured for predicting the location of damage by reducing the ranking of the perturbation matrices. The results are then verified by different damage scenarios. The influence of the ambient noise is also evaluated by simulating different degrees of noise in the modal data. As a result of the proposed methodology, location and severity of damage is obtained with high accuracy. The obtained results indicated that the presented methodology is a reliable approach for evaluating and estimating nonlinear damage detection in the presence of ambient noise
  9. Keywords:
  10. Damage Detection ; Nonlinear Behavior ; Modal Data ; Model Updating ; Hysteresis Behavior ; Bouc-Wen Dynamic Model

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