DNVGL-OS-C101: Design of offshore steel structures ...

1 offshore STANDARD. DNVGL-OS-C101 Edition July 2015. Design of offshore steel structures , general - LRFD method The electronic pdf version of this document found through is the officially binding version. The documents are available free of charge in PDF format. DNV GL AS. FOREWORD. DNV GL offshore standards contain technical requirements, principles and acceptance criteria related to classification of offshore units. DNV GL AS July 2015. Any comments may be sent by e-mail to This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document. The use of this document by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility for loss or damages resulting from any use of this document.

2 CHANGES CURRENT. Changes current General This document supersedes DNV-OS-C101, July 2014. Text affected by the main changes in this edition is highlighted in red colour. However, if the changes involve a whole chapter, section or sub-section, normally only the title will be in red colour. On 12 September 2013, DNV and GL merged to form DNV GL Group. On 25 November 2013 Det Norske Veritas AS became the 100% shareholder of Germanischer Lloyd SE, the parent company of the GL Group, and on 27 November 2013 Det Norske Veritas AS, company registration number 945 748 931, changed its name to DNV GL AS. For further information, see Any reference in this document to Det Norske Veritas AS , Det Norske Veritas , DNV , GL , Germanischer Lloyd SE , GL Group or any other legal entity name or trading name presently owned by the DNV GL Group shall therefore also be considered a reference to DNV GL AS.

3 Main changes General The revision of this document is part of the DNV GL merger, updating the previous DNV standard into a DNV. GL format including updated nomenclature and document reference numbering, : Main class identification 1A1 becomes 1A. DNV replaced by DNV GL. DNV-RP-A201 to DNVGL-CG-0168. A complete listing with updated reference numbers can be found on DNV GL's homepage on internet. To complete your understanding, observe that the entire DNV GL update process will be implemented sequentially. Hence, for some of the references, still the legacy DNV documents apply and are explicitly indicated as such, : Rules for Ships has become DNV Rules for Ships. Editorial corrections In addition to the above stated main changes, editorial corrections may have been made.

4 offshore standard, DNVGL-OS-C101 Edition July 2015 Page 3. Design of offshore steel structures , general - LRFD method DNV GL AS. Contents CONTENTS. CHANGES CURRENT .. 3. CH. 1 INTRODUCTION .. 9. Introduction .. 9. 1 General ..9. Objectives ..9. Scope and application ..9. Other than DNV GL codes .. 10. 10. 2 General .. 10. 3 Definitions ..11. Verbal forms .. 11. Terms .. 11. 4 Abbreviations and symbols ..14. Abbreviations .. 14. Symbols .. 15. CH. 2 TECHNICAL 17. Design 17. 1 Introduction ..17. General .. 17. Aim of the Design .. 17. 2 General Design considerations ..17. General .. 17. 3 Limit General .. 18. 4 Design by LRFD method ..19. General .. 19. The load and resistance factor Design format (LRFD).

5 19. Characteristic load .. 20. Load factors for 20. Load factor for FLS .. 21. Load factor for SLS .. 21. Load factor for ALS .. 21. 5 Design assisted by testing ..21. General .. 21. Full-scale testing and observation of performance of existing structures .. 21. 6 Probability based Definition .. 22. General .. 22. Loads and load 23. 1 Introduction ..23. General .. 23. Scope .. 23. offshore standard, DNVGL-OS-C101 Edition July 2015 Page 4. Design of offshore steel structures , general - LRFD method DNV GL AS. 2 Basis for selection of characteristic loads ..23. Contents General .. 23. 3 Permanent loads (G) ..24. General .. 24. 4 Variable functional loads (Q) ..24. General .. 24. Variable functional loads on deck 24.

6 Tank 25. Lifeboat 26. 5 Environmental loads (E) ..26. General .. 26. Environmental loads for mobile offshore 26. Environmental loads for site specific units .. 26. Determination of characteristic hydrodynamic loads .. 27. Wave loads .. 27. Wave induced inertia forces .. 28. Wind loads .. 28. Vortex induced oscillations .. 28. Current .. 28. Tidal effects .. 29. Marine growth .. 29. Snow and ice accumulation .. 29. Direct ice load .. 29. Water level, settlements and erosion .. 29. Earthquake .. 29. 6 Combination of environmental loads ..30. General .. 30. 7 Accidental loads (A) ..31. General .. 31. 8 Deformation loads (D) ..31. General .. 31. Temperature 31. Settlements and subsidence of sea bed.

7 31. 9 Load effect analysis ..32. General .. 32. Global motion analysis .. 32. Load effects in structures and soil or foundation .. 32. Structural categorisation, material selection and inspection principles .. 34. 1 2 Temperatures for selection of material ..34. General .. 34. Floating units .. 34. Bottom fixed units .. 34. 3 Structural category ..34. General .. 34. Selection of structural category .. 35. Inspection of welds .. 35. 4 Structural steel ..36. General .. 36. Material designations .. 36. Selection of structural 38. offshore standard, DNVGL-OS-C101 Edition July 2015 Page 5. Design of offshore steel structures , general - LRFD method DNV GL AS. Fracture mechanics testing .. 39. Contents Post weld heat 39.

8 Ultimate limit 40. 1 General ..40. General .. 40. Structural analysis .. 40. Ductility .. 40. Yield check .. 41. Buckling check .. 41. 2 Flat plated structures and stiffened panels ..42. General .. 42. Yield check .. 42. Buckling check .. 42. Capacity checks according to other codes .. 42. 3 Shell structures ..42. General .. 42. 4 Tubular members, tubular joints and conical transitions ..43. General .. 43. 5 Non-tubular beams, columns and General .. 43. 6 Special provisions for plating and stiffeners ..43. Scope .. 43. Minimum thickness .. 44. Bending of plating .. 44. Stiffeners .. 44. 7 Special provisions for girder and girder systems ..45. Scope .. 45. Minimum thickness .. 45. Bending and shear.

9 45. Effective flange .. 46. Effective web .. 46. Strength requirements for simple girders .. 46. Complex girder 48. 8 Slip resistant bolt General .. 48. Fatigue limit states .. 51. 1 General ..51. General .. 51. Design fatigue factors .. 51. Methods for fatigue 52. Accidental limit states .. 53. 1 General ..53. General .. 53. Serviceability limit states .. 54. 1 General ..54. General .. 54. Deflection criteria .. 54. Out of plane deflection of local plates .. 55. offshore standard, DNVGL-OS-C101 Edition July 2015 Page 6. Design of offshore steel structures , general - LRFD method DNV GL AS. Weld connections .. 56. Contents 1 General ..56. 2 Types of welded steel joints ..56. Butt joints .. 56.

10 Tee or cross joints .. 56. Slot 57. Lap 58. 3 Weld size ..58. General .. 58. Fillet welds .. 59. Partly penetration welds and fillet welds in cross connections subject to high 59. Connections of stiffeners to girders and bulkheads etc.. 60. End connections of girders .. 62. Direct calculation of weld 62. Corrosion control .. 64. 1 Introduction ..64. 2 Techniques for corrosion control related to environmental Atmospheric zone .. 64. Splash zone .. 64. Submerged zone .. 65. Internal zones .. 65. 3 Cathodic protection ..66. General .. 66. Galvanic anode systems .. 67. Impressed current systems .. 67. 4 Coating systems ..68. Specification of 68. Foundation 69. 1 General ..69. 69. Site investigations.