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Performance of Jacket Platforms Equipped with RBS (Ribbed Bracing System) under Dynamic Loads

Hajinoori, Yaghoob Ali | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45008 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Golafshani, Ali Akbar; Tabeshpour, Mohamad Reza
  7. Abstract:
  8. Offshore platforms are one of the most important structures in oil-rich countries, so that their economic benefit makes it very expensive to stop their usage. Therefore, it is essential that their performance is not disrupted by earthquake or the tidal waves made by severe storms. The new high performance semi-active bracing system, developed by Golafshani et al, is capable of removing the permanent drift of stories at the end of excitation and concentrating structural damage in braces. In the conventional bracing systems it is assumed that the braces buckle under little compressive forces; but in this new presented completely tensile-ribbed bracing system (RBS), buckling of compressive member is prevented by using of a ribbed shape cylinder. The brace equipped with this system loses its length under pressure effect; in contrast with conventional braces, this brace can receive tensile force at any point during its return. Therefore, brace equipped with this system can apply a continuously variable stiffness to structure during earthquakes. RBS system has no need to any actuator and large power supply, but just a battery to switch the ribbed mechanism on or off. In previous researches, the proper functioning of the brace has been observed on the steel frames. In this study performance of this system in jacket platform, with a case study of Resalat platform, has been investigated under earthquake load and powerful waves, with modeling of jacket equipped with this brace in OpenSees software, and results have been compared with responses of jacket with conventional bracing frame (CBF). To do this study, the nonlinear dynamic analysis under various earthquake records and also the wave force under extreme sea state have been investigated on the platforms with conventional braces and equipped with RBS. The results show that this system has a lower dynamic response than conventional braces in extreme state
  9. Keywords:
  10. Semiactive Control ; Jacket Platform ; High Performance Bracing ; Seismic Load ; Wave Loading ; Ribbed Bracing System (RBS)

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