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SUC Brasil 2012 : Sesam for Topsides
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SUC Brasil 2012 : Sesam for Topsides

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Presentation of Sesam Genie for Topside Analysis, delivered at SUC by Ole Jan Nekstad from DNV.

Presentation of Sesam Genie for Topside Analysis, delivered at SUC by Ole Jan Nekstad from DNV.

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  • 1. 1SesamTM40 years of successEfficient engineering of topside structuresOle Jan Nekstad, Product Director Sesam3 December 2012
  • 2. Efficient engineering of topside structures Save man-hours and increase quality by using the latest available capabilities in concept technologies for - Structure modelling - Deadweight loads - Environmental loads - Forces, stresses, deflections - Beam/plate code checking - Fatigue from wave or wind - Refined fatigue - ULS, FLS, ALSSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 2
  • 3. Topside structures (including modules, flare booms, bridges) On jacket On floater - Often members only - Often plates and stiffeners and membersSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 3
  • 4. Common challenges in designSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 4
  • 5. The importance of the Sesam design loop 40-60% of engineering time often spent in evaluation How fast can you do it over again?SesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 5
  • 6. How can Sesam GeniE help you to design a topside structure StructureSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 6
  • 7. Structure modelling Easy to facilitate the range from small to large and complexSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 7
  • 8. Structure modelling Combine detailed models in a global model Beam - FE results, SCF for beam fatigue, plate fatigue Plates FE beam FE shellSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 8
  • 9. Structure modelling Make the complete model in Sesam GeniE - Beams, plates, trusses, double beams, segmented members, auto creation of tubular joints, connections - Automatic model update when inserting, deleting, moving, copying - The model topology is always updated, hence major changes in the model may easily be performed - You may be become more productive by using scripting and parametric modelling - Several engineers can work on parts of the topside and merge prior to analysis - Result evaluation may also be performed on same parts - Same model and loads may be used for several loading conditions Re-use data and continue modelling in GeniE - Older Sesam models - Sacs, StaadPro, StruCad3D, AnsysSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 9
  • 10. How can Sesam GeniE help you to design a topside structure Deadweight loadsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 10
  • 11. Deadweight loads From structural mass x gravity From point masses x gravity Blanket loads (evenly distributed mass) Equipments Specific pressure loads, point or line loads Mass of ice x gravity (same as marine growth for jacket) Compartment loads Temperature loadsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 11
  • 12. Deadweight loads When jack-up is in “fixed structure” modus. Easy to define compartment loads - Content and filling degree is enough to compute the acting pressures in the wallsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 12
  • 13. How can Sesam GeniE help you to design a topside structure Environmental loadsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 13
  • 14. Topsides/modules on jackets or floaters Topside on jackets Topside on floaters - All is done inside Sesam GeniE - Opt. 1 - Integrated: Results from Sesam HydroD - Wind, current, wave (hydrodynamic frequency or time domain - Morison theory analysis) imported into Sesam GeniE - Deterministic, stochastic, time domain - Opt. 2 - No load transfer: Accelerations and deflections are computed in Sesam HydroD and - Non-linear pile/soil analysis normally included used as basis for load-cases in Sesam GeniESesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 14
  • 15. Option 1: Topsides/modules on floaters Waves give deformations and stresses in topsides and modules - These are converted to deterministic loads before import to Sesam GeniESesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 16
  • 16. Option 2: Topsides/modules on floaters Deformations and accelerations used to define load cases in Sesam GeniE - Accelerations constant or centripetal (from Sesam HydroD) - Deformations from global structural analysis (used as prescribed displacements in GeniE) Sp1: 2mm Sp2: 3mm Sp3: 5mm Centripetal Acceleration Sp4: 2mmSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 17
  • 17. Topsides/modules on jackets Codes of practice specify different safety factors for structural mass on various parts of the structure Sesam GeniE can work with different load factors for structure mass by using a utility script as found on the Sesam GeniE SnackPack - I.e. Force = acceleration x mass x load factor Lower level loads from mass Upper level loads from Rotational acceleration x acceleration (x & z-dir) mass x acceleration (z-dir) Harmonic induced wave motionSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 18
  • 18. How can Sesam GeniE help you to design a topside structure Results assessmentSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 19
  • 19. Efficient engineering – typical steps First assessment - Forces, stresses and deflections Code checking - Check against prescriptive standards Member re-design - Evaluate the effect of modifying section properties or code check parameters - Often many attempts – depends on the engineer’s experience Design iteration - A complete re-run of all to document the re-designSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 20
  • 20. Beam forces and stresses Forces and stresses in 2D view as well as tabularSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 21
  • 21. Check deflection ratio against AISC levels Allowable deflection ratio 180, 240, 360 and scanning all load casesSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 22
  • 22. How can Sesam GeniE help you to design a topside structure Code checking of members & stiffened panelsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 23
  • 23. Code checking in GeniE - members Supporting - API WSD 2002/AISC ASD 2005 - API WSD 2005/AISC ASD 2005 (API: 2007, 2010 updates) - API LRFD 2003/AISC LRFD 2005 (withdrawn by API) - NORSOK 2004/Eurocode 3 1993 (EC: 2008, 2009, 2010 updates) - ISO 19902 2007/Eurocode 3 1993 (EC: 2008, 2009, 2010 updates) - DS 412/449SesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 24
  • 24. Document code check results Graphically – complete modelSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 25
  • 25. Document code check results Graphically – parts of structure onlySesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 26
  • 26. Efficient redesign of members Redesign (“design iterations”) - Step1: Preliminary results when modifying section, material, stiffener spacing or buckling length parameters - Note: The loads and stiffness are not updated - Step2: Commit changes to model - Step3: Re-run analysis and code check - Reports may be automatically re-createdSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 27
  • 27. Redesign – single members Select a capacity member for redesign Modify parameters - Preliminary results automatically computedSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 28
  • 28. Redesign – single members Look at all details (Full Table) - Shown with colour codingSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 29
  • 29. Redesign – multiple members Select capacity members for redesign Modify parameters - Preliminary results automatically computedSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 30
  • 30. Redesign – segmented beams Before and afterSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 31
  • 31. Redesign – re-run all from one command The “Run All” command will - Update structure from members - Run analysis - Generate code check loads (positions) - Execute code check Recreation of a reportSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 32
  • 32. Code checking of stiffened panels Create panels - Panels are independent of analysis and finite element mesh Three different options to define panels - Min Box finds the smallest idealised rectangular panel possible enclosing the possibly non- rectangular structural region - Max Area Moment is an alternative algorithm finding the major axis based on calculation of area moment of inertia of the surface. This algorithm will also work for irregular panel Min Box shapes - CSR Tank Default is the algorithm usually used when doing a CSR Tank (PULS) code check Max Area MomentSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 33
  • 33. Code checking of stiffened panels – ships and offshore Code checking according to PULS (DNV RP-C201.2) - Linear and non-linearSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 34
  • 34. Code checking of stiffened panels - offshore Yield check of plates – based on membrane stress - Includes a safety factor SSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 35
  • 35. How can Sesam GeniE help you to design a topside structure Multiple analysisSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 36
  • 36. Multiple analysis The “master” Multiple analysis in same project model - E.g. Lifting, transport, in-place - Varying parameters - Structure - Boundary conditions - Load casesLifting Condition Transport Condition In_place ConditionSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 37
  • 37. Multiple analysis – graphic results Different results at your finger-tips - Bending moments shown Lifting Condition Transport Condition In_place ConditionSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 38
  • 38. Multiple analysis – code check results Different results at your finger-tips - API WSD and default settings used in example below Lifting Condition Transport Condition In_place Condition Max Uf = 2.51 Max Uf = 1.85 Max Uf = 4.58SesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 39
  • 39. Multiple analysis Frigg TCP2 MSF removal Transportation MSF: Main Support Frame Lifting ConditionSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 40
  • 40. How can Sesam GeniE help you to design a topside structure FatigueSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 41
  • 41. Fatigue of topsides Sesam supports 3 options - Deterministic fatigue (regular waves, time domain wave load analysis) - More accurate wave loads (any theory and proper drag) - Simple and straight forward - Stochastic fatigue (spectral wave load analysis) - Structural dynamics and better coverage of environmental conditions - Prior to fatigue analysis partial damage may be set - Time domain fatigue (irregular waves, time domain wave load analysis) – also known as Rainflow Counting Fatigue (RFC) - Wave loads to instantaneous free surface (also for irregular sea states) - Non-linear pile soil effectsSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 42
  • 42. Fatigue of topsides Include a refined shell model (finite element model) in the global model for the purpose of computing stresses, SCF’s for beam fatigue or direct shell fatigue Use the GeniE SnackPack to auto convert from beam to shellSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 43
  • 43. Fatigue of topsides Results can be used to derive SCF for use in traditional beam fatigue Results can be used to do fatigue of shells – FE size same as thickness and should be as quadratic as possibleSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 44
  • 44. Safeguarding life, property and the environment www.dnv.comSesamTM3 December 2012© Det Norske Veritas AS. All rights reserved. 45