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Sensitivity analysis of simple methods in determination of offshore jacket structures levels stiffness

Tabeshpour, M.R ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1007/s00773-021-00856-4
  3. Publisher: Springer Japan , 2022
  4. Abstract:
  5. Dynamic analyses are necessary problems in offshore jacket structures design and assessment. These analyses have various applications in recognition of dynamic behavior, fatigue analysis, damage detection, etc. Natural frequencies and mode shapes, as inherent vibrational features of a structure, are key parameters in referred analyses. These parameters are mainly affected by mass and stiffness matrices and slightly by damping. Therefore, it is more important to estimate the stiffness matrix of a structure accurately, especially in stiff structures such as offshore jacket platforms. In many cases, the stiffness of levels is required. For example, it can be useful in the construction of an equivalent shear building model. This reduced equivalent model can be useful in damage detection, soft-story control in design criteria, or a simple vibrational model in frequency domain analyses. So, using a simple, fast and reliable method to general and primary calculation of stiffness of such a structure can be efficient. This paper deals with the assessment of six different stiffness calculation methods and implementation of them on a service offshore jacket structure installed in the Persian Gulf. The main idea in the definition of methods is the difference in load pattern and boundary conditions. Level lateral and torsional stiffness of the structure is calculated using the methods and compared with values extracted by the Finite Element Method (FEM). In addition, sensitivity analysis of methods carries out for such a platform. The results show that the right recreation of lateral modal specifications, unlike torsional mode, are very sensitive to the equivalent stiffness calculation method. In addition, it is shown that methods based on wave or earthquake load patterns are the best solution to reach the right model. © 2021, The Japan Society of Naval Architects and Ocean Engineers (JASNAOE)
  6. Keywords:
  7. Dynamic analysis ; Offshore jacket structures ; Story stiffness ; Behavioral research ; Damage detection ; Frequency domain analysis ; Sensitivity analysis ; Stiffness matrix ; Structural design ; Vibration analysis ; Dynamic behaviors ; Dynamics analysis ; Fatigue analysis ; Load patterns ; SIMPLE method ; Stiffness calculations ; Stiffness matrices ; Structure design ; Stiffness
  8. Source: Journal of Marine Science and Technology (Japan) ; Volume 27, Issue 1 , 2022 , Pages 619-636 ; 09484280 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s00773-021-00856-4