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Damage Detection in an Offshore Jacket Platform Using Finite Element Model Updating Method

Malek Zehtab, Hassan | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42446 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Golafshani, Ali Akbar
  7. Abstract:
  8. Offshore jacket platforms are one of the most motivating structures for damage detection due to their importance and productivity. In this study, the goal is to investigate the application of finite element model updating as a robust method for damage detection in this kind of structure. This method is based on minimizing a cost function which shows the difference between some features of the model and damaged real structure. Therefore, this method can be used for damage detection by comparison between updated model, which is updated by measured data from damaged structure, and the initial model which precisely shows the previous or undamaged status of the structure. The vibration features including modal data is used as updating criteria. Also, computational intelligence methods, including Genetic Algorithm (GA) and Particle Swarm Optimization (PSO), are exploited as a powerful method for updating the model by minimizing the explained cost function. These updating methods are modified for better results. Furthermore, a penalty function is added to cost function to avoide false damage in the results. Then, the efficiency of these algorithms is examined with different damage cases including single and multi-damaged scenarios. Furthermore, the effects of the number of used modes and noisy data are investigated too. The results indicate that the results of both GA and PSO are almost exact if the members have participated in modal data which is taken into account. However, GA is less sensitive to the lack of modal data and also can reach to acceptable results even if the data is noisy
  9. Keywords:
  10. Damage Identification ; Offshore Platforms ; Finite Element Model ; Genetic Algorithm ; Particles Swarm Optimization (PSO) ; Model Updating ; Modal Data

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