Tài liệu UiARINE TRUCTURAL DESIGN Ultimate strength, Fatigue and frature Structural reliability pptx

LV iARINE

U TRUCTURAL

DESIGN

Ultimate strength, Structural reliability,

Fatigue and frature Risk assessment Loads Functional

requirements

I I I I

Limit-state design

R(ftJym,...,) > S(Y,Q,)

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MARINE STRUCTURAL DESIGN

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MARINE STRUCTURAL DESIGN

YONG BAI

2003

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Bai, Yong

Marine Structural Design

1. Offshore structures - Design and construction 2. Marine

engineering

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627.9’8

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8 The paper used in this publication meets the requirements of ANSVNISO 239.48-1992 (Permanence of Paper).

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PREFACE

This book is written for marine structural engineers and naval architects, as well as mechanical

engineers and civil engineers who work on struch~ral design. The preparation of the book is

motivated by extensive use of the finite element analysis and dynamidfatigue analysis, fast paced

advances in computer and information technology, and application of risk and reliability methods.

As the professor of offshore structures at Stavanger University College, I developed this book for my

teaching course TE 6076 “Offshore Structures” and TE6541 “Risk and Reliability Analysis of

Offshore Structures” for M.Sc and Ph.D. students. This book has also been used in IBC/Clarion

industry training courses on design and construction of floating production systems for engineers in

the oil/@ industry.

As reliability-based limit-state design becomes popular in structural engineering, this book may also

be a reference for structural engineers in other disciplines, such as buildings, bridges and spacecraft.

My former supervisors should be thanked for their guidance and inspiration. These include:

Executive Vice President Dr. Donald Liu at American Bureau of Shipping (ABS), Professor Torgeir

Moan at Norwegian University of Science and Technology 0, Professor Robert Bea and

Professor Alaa Mansour at University of California at Berkeley, Prof. Preben Terndrup Pedersen at

Technical University of Denmark, Professor T. Yao at Osaka University and Professor M. Fujikubo

at Hiroshima University. The friendship and technical advice from these great scientists and

engineers have been very important for me to develop materials used in this book.

As manager of advanced engineering department at JP Kenny Norway office (now a section of ABB)

and manager of offshore technology department at the American Bureau of Shipping, I was given

opportunities to meet many industry leaders in oil companies, desigdconsulting offices,

classification societies and contractors. From ISSC, IBC, SNM, OMAE, ISOPE and OTC

conferences and industry (ISO/APYDeepstar) committees, I leamed about the recent developments

in industry applications and research.

The collaboration with Dr. Ruin Song and Dr. Tao Xu for a long period of time has been helpful to

develop research activities on structural reliability and fatigue respectively. Sections of this book

relating to extreme response, buckling of tubular members, FPSO hull girder strength and reliability

were based on my SNAME, 0- and ISOPE papers co-authored with Professors Preben Temdrup

Pedersen and T. Yao and Drs. Yung Shin, C.T. Zhao and H.H. Sun.

Dr. Qiang Bai and Ph.D. student Gang Dong provided assistance to format the manuscript.

Professor Rameswar Bhattacharyya, Elsevier’s Publishing Editor James Sullivan and Publisher Nick

Pinfield and Senior Vice President James Card of ABS provided me continued encouragement in

completing this book.

I appreciate my wife Hua Peng and children, Lihua and Carl, for creating an environment in which it

has been possible to continue to write this book for more than 5 years in different culture and

working environments.

I wish to thank all of the organizations and individuals mentioned in the above (and many friends

and authors who were not mentioned) for their support and encouragement.

Yong BAI

Houston, USA

TABLE OF CONTENTS

Preface ................................................................................................................................................ v

Part I: Structural Design Principles

CHAPTER 1 INTRODUCTION ......................................................................................................... 3

Structural Design Principles ........................................................................................................ 3

1.1.1 Introduction .......................................................................................................................... 3

1.1.2 Limit-State Design ............................................................................................................... 4

1.2 Strength and Fatigue Analysis ..................................................................................................... 5

1.2.1 Ultimate Strength Criteria .................................................................................................... 6

1.2.2 Design for Accidental Loads ................................................................................................ 7

1.2.3 Design for Fatigue ................................................................................................................ 8

1.3 Structural Reliability Applications ............................................................................................ 10

1.3.1 Structural Reliability Concepts .......................................................................................... 10

1.3.2 Reliability-Based Calibration of Design Factor ................................................................. 12

1.3.3 Requalification of Existing Structures .............................................................................. 12

1.4 Risk Assessment ........................................................................................................................ 13

1.4.1 Application of Risk Assessment ........................................................................................ 13

1.4.2 Risk-Based Inspection (RBI) ............................................................................................. 13

1.4.3 Human and Organization Factors ....................................................................................... 14

1.5 Layout of This Book .................................................................................................................. 14

1.6 How to Use This Book .............................................................................................................. 16

1.7 References ................................................................................................................................. 16

CHAPTER 2 WAVE LOADS FOR SHIP DESIGN AND CLASSIFICATION .......................... 19

2.1 Introduction ............................................................................................................................... 19

2.2 Ocean Waves and Wave Statistics ............................................................................................. 19

2.2.1 Basic Elements of Probability and Random Process .......................................................... 19

2.2.2 Statistical Representation of the Sea Surface ..................................................................... 21

2.2.3 Ocean Wave Spectra .......................................................................................................... 22

2.2.4 Moments of Spectral Density Function .............................................................................. 24

2.2.5 Statistical Determination of Wave Heights and Periods .................................................... 26

2.3 Ship Response to a Random Sea ............................................................................................... 26

2.3.1 Introduction ........................................................................................................................ 26

2.3.2 Wave-Induced Forces ......................................................................................................... 28

2.3.3 Structural Response ............................................................................................................ 29

2.3.4 Slamming and Green Water on Deck ................................................................................. 30

Ship Design for Classification ................................................................................................... 32

2.4.1 Design Value of Ship Response ......................................................................................... 32

2.4.2 Design Loads per Classification Rules ............................................................................... 33

2.5 References ................................................................................................................................. 35

CHAPTER 3 LOADS AND DYNAMIC RESPONSE FOR OFFSHORE STRUCTURES ........ 39

3.1 General ....................................................................................................................................... 39

1.1

2.4

viii Contents

3.2 Environmental Conditions ......................................................................................................... 39

3.2.1 Environmental Criteria ....................................................................................................... 39

3.2.2 Regular Waves ................................................................................................................... 41

3.2.3 Irregular Waves .................................................................................................................. 41

3.2.4 Wave Scatter Diagram ....................................................................................................... 42

3.3 Environmental Loads and Floating Structure Dynamics ........................................................... 45

3.3.1 Environmental Loads ......................................................................................................... 45

3.3.2 Sea loads on Slender Structures ......................................................................................... 45

3.3.3 Sea loads on Large-Volume Structures .............................................................................. 45

3.3.4 Floating Structure Dynamics .............................................................................................. 46

3.4 Structural Response Analysis .................................................................................................... 47

3.4.1 Structural Analysis ............................................................................................................. 47

3.4.2 Response Amplitude Operator (RAO) ............................................................................... 49

3.5 Extreme Values .......................................................................................................................... 53

3.5.1 General ............................................................................................................................... 53

3.5.2 Short-Term Extreme Approach .......................................................................................... 54

3.5.3 Long-Term Extreme Approach .......................................................................................... 58

3.5.4 Prediction of Most Probable Maximum Extreme for Non-Gaussian Process .................... 61

3.6 Concluding Remarks ................................................................................................................. 65

3.7 References ................................................................................................................................. 66

3.8 Appendix A Elastic Vibrations of Beams ................................................................................. 68

3.8.1 Vibration of A Springhiass System .................................................................................. 68

3.8.2 Elastic Vibration of Beams ................................................................................................ 69

CHAPTER 4 SCANTLING OF SHIP'S HULLS BY RULES ....................................................... 71

4.1 General ....................................................................................................................................... 71

4.2 Basic Concepts of Stability and Strength of Ships .................................................................... 71

4.2.1 Stability .............................................................................................................................. 71

4.2.2 Strength .............................................................................................................................. 73

4.2.3 Corrosion Allowance ......................................................................................................... 75

4.3 Initial Scantling Criteria for Longitudinal Strength ................................................................... 76

4.3.1 Introduction ........................................................................................................................ 76

4.3.2 Hull Girder Strength ........................................................................................................... 77

4.4 Initial Scantling Criteria for Transverse Strength ...................................................................... 79

4.4.1 Introduction ........................................................................................................................ 79

4.4.2 Transverse Strength ............................................................................................................ 79

4.5 Initial Scantling Criteria for Local Strength .............................................................................. 79

4.5.1 Local Bending of Beams .................................................................................................... 79

4.5.2 Local Bending Strength of Plates ....................................................................................... 82

4.5.3 Structure Design of Bulkheads, Decks, and Bottom .......................................................... 83

4.5.4 Buckling of Platings ........................................................................................................... 83

4.5.5 Buckling of Profiles ........................................................................................................... 85

4.6 References ................................................................................................................................. 87

CHAPTER 5 SHIP HULL SCANTLING DESIGN BY ANALYSIS ............................................ 89

5.1 General ....................................................................................................................................... 89

5.2 Design Loads ............................................................................................................................. 89

5.3 Strength Analysis using Finite Element Methods ...................................................................... 91

5.3.1 Modeling ............................................................................................................................ 91

5.3.2 Boundary Conditions ......................................................................................................... 93

5.3.3 Type of Elements ............................................................................................................... 94

5.4 Fatigue Damage Evaluation ....................................................................................................... 95

5.3.4 Post-Processing .................................................................................................................. 94

Contents ir

5.5 References ................................................................................................................................. 97

CHAPTER 6 OFFSHORE STRUCTURAL ANALYSIS ............................................................... 99

6 .I Introduction ............................................................................................................................... 99

6.1 . 1 General ............................................................................................................................... 99

6.1.2 Design Codes ..................................................................................................................... 99

6.1.3 Government Requirements ............................................................................................... 100

6.1.4 CertificatiodClassification Authorities ............................................................................ 100

6.1.5 Codes and Standards ........................................................................................................ 101

6.1.6 Other Technical Documents ............................................................................................. 102

6.2 Project Planning ....................................................................................................................... 102

6.2.1 General ............................................................................................................................. 102

6.2.2 Design Basis ..................................................................................................................... 103

6.2.3 Design Brief ..................................................................................................................... 105

6.3 Use of Finite Element Analysis ............................................................................................... 105

6.3.1 Introduction ...................................................................................................................... 105

6.3.2 Stiffness Matrix for 2D Beam Elements .......................................................................... 107

6.3.3 Stifmess Matrix for 3D Beam Elements .......................................................................... 109

6.4 Design Loads and Load Application ....................................................................................... 112

6.5 Structural Modeling ................................................................................................................. 114

6.5.1 General ............................................................................................................................. 114

6.5.2 Jacket Structures ............................................................................................................... 114

6.5.3 Floating Production and Offloading Systems (FPSO) ..................................................... 116

6.5.4 TLP, Spar and Semi-submersible ..................................................................................... 123

6.6 References ............................................................................................................................... 125

CHAPTER 7 LIMIT-STATE DESIGN OF OFFSHORE STRUCTURES ................................ 127

7.1 Limit State Design ................................................................................................................... 127

7.2 Ultimate Limit State Design .................................................................................................... 128

7.2.1 Ductility and Brittle Fracture Avoidance ......................................................................... 128

7.2.2 Plated Structures ............................................................................................................... 129

7.2.3 Shell Structures ................................................................................................................ 130

7.3.1 Introduction ...................................................................................................................... 134

7.3.3 Fatigue Design ................................................................................................................. 137

7.4 References ............................................................................................................................... 138

7.3 Fatigue Limit State Design ...................................................................................................... 134

7.3.2 Fatigue Analysis ............................................................................................................... 135

Part 11: Ultimate Strength

CHAPTER 8 BUCKLINGKOLLAPSE OF COLUMNS AND BEAM-COLUMNS ................ 141

Buckling Behavior and Ultimate Strength of Columns ........................................................... 141

8.1.1 Buckling Behavior ........................................................................................................... 141

8.1.2 Peny-Robertson Formula ................................................................................................. 143

8.1.3 Johnson-Ostenfeld Formula ............................................................................................. 144

8.2 Buckling Behavior and Ultimate Strength of Beam-Columns ................................................ 145

8.2.1 Beam-Column with Eccentric Load ................................................................................. 145

8.2.2 Beam-Column with Initial Deflection and Eccentric Load .............................................. 146

8.2.3 Ultimate Strength of Beam-Columns ............................................................................... 147

8.2.4

8.3.1

8.1

Alternative Ultimate Strength Equation - Initial Yielding .............................................. 148

Plastic Design of Beam-Columns ............................................................................................ 148

Plastic Bending of Beam Cross-section ........................................................................... 148

8.3

X Contents

8.3.2

8.3.3

8.4.1

8.4.2

Plastic Hinge Load ........................................................................................................... 150

Plastic Interaction Under Combined Axial Force and Bending ....................................... 150

8.4 Examples ................................................................................................................................. 151

Example 8.1: Elastic Buckling of Columns with Alternative Boundaty Conditions ....... 151

Example 8.2 Two Types of Ultimate Strength Buckling vs . Fracture ........................... 153

8.5 References ............................................................................................................................... 154

CHAPTER9 BUCKLING ANDLOCALBUCKLINGOFTUBULARMEMBERS ............... 155

9.1 Introduction ............................................................................................................................. 155

9.1.1 General ............................................................................................................................. 155

9.1.2 Safety Factors for Offshore Strength Assessment ............................................................ 156

9.2.1 Test Specimens ................................................................................................................. 156

9.2.2 Material Tests ................................................................................................................... 158

9.2.3 Buckling Test Procedures ................................................................................................ 163

9.2.4 Test Results ...................................................................................................................... 163

Theory of Analysis .................................................................................................................. 169

9.3.1 Simplified Elasto-Plastic Large Deflection Analysis ....................................................... 169

9.3.2 Idealized Structural Unit Analysis ................................................................................... 180

9.4 Calculation Results .................................................................................................................. 186

9.4.1 Simplified Elasto-Plastic Large Deflection Analysis ....................................................... 186

9.4.2 Idealized Structural Unit Method Analysis ...................................................................... 190

9.2 Experiments ............................................................................................................................. 156

9.3

9.5 Conclusions ............................................................................................................................. 194

9.6 Example ................................................................................................................................... 195

9.7 References ............................................................................................................................... 196

CHAPTER 10 ULTIMATE STRENGTH OF PLATES AND STIFFENED PLATES ............... 199

10.1 Introduction ............................................................................................................................. 199

10.1.1 General ............................................................................................................................. 199

10.1.2 Solution of Differential Equation ..................................................................................... 200

10.1.3 Boundary Conditions ....................................................................................................... 202

10.1.5 Correction for Plasticity ................................................................................................... 204

10.2 Combined Loads ...................................................................................................................... 205

10.2.1 Buckling - Serviceability Limit State .............................................................................. 205

10.2.2 Ultimate Strength - Ultimate Limit State ........................................................................ 206

10.3 Buckling Strength of Plates ..................................................................................................... 207

10.4 Ultimate Strength of Un-Stiffened Plates ................................................................................ 208

10.4.1 Long Plates and Wide Plates ............................................................................................ 208

10.4.2 Plates Under Lateral Pressure .......................................................................................... 209

10.4.3 Shear Strength .................................................................................................................. 209

10.4.4 Combined Loads .............................................................................................................. 209

10.5 Ultimate Strength of Stiffened Panels ..................................................................................... 209

10.5.1 Beam-Column Buckling ................................................................................................... 209

10.5.2 Tripping of Stiffeners ....................................................................................................... 210

10.6 Gross Buckling of Stiffened Panels (Overall Grillage Buckling) ............................................ 210

10.7 References ............................................................................................................................... 210

CHAPTER 11 ULTIMATE STRENGTH OF CYLINDRICAL SHELLS ................................... 213

1 1.1 Introduction ............................................................................................................................. 213

11.1.1 General ............................................................................................................................. 213

11.1.2 Buckling Failure Modes ................................................................................................... 214

11.2 Elastic Buckling of Unstiffened Cylindrical Shells ................................................................. 215

10.1.4 Fabrication Related Imperfections and In-Service Structural Degradation ..................... 202

Contents xi

11.2.1 Equilibrium Equations for Cylindrical Shells .................................................................. 215

11.2.2 Axial Compression ........................................................................................................... 216

11.2.3 Bending ............................................................................................................................ 217

11.2.4 External Lateral Pressure ................................................................................................. 218

11.3 Buckling of Ring Stiffened Shells ........................................................................................... 219

1 1.3.1 Axial Compression ........................................................................................................... 219

11.3.2 Hydrostatic Pressure ......................................................................................................... 220

11.3.3 Combined Axial Compression and Pressure .................................................................... 221

11.4 Buckling of Stringer and Ring Stiffened Shells ....................................................................... 221

1 1.4.1 Axial Compression ........................................................................................................... 221

1 1.4.2 Radial Pressure ................................................................................................................. 223

11.4.3 Axial Compression and Radial Pressure .......................................................................... 223

1 1.5 References ............................................................................................................................... 224

CHAPTER 12 A THEORY OF NONLINEAR FINITE ELEMENT ANALYSIS ............ 227

12.1 General ..................................................................................................................................... 227

12.2 Elastic Beam-Column With Large Displacements .................................................................. 228

12.3 The Plastic Node Method ........................................................................................................ 229

12.3.1 History of the Plastic Node Method ................................................................................. 229

12.3.2 Consistency Condition and Hardening Rates for Beam Cross-Sections .......................... 230

12.3.3 Plastic Displacement and Strain at Nodes ........................................................................ 233

12.4 Transformation Matrix ............................................................................................................. 236

12.5 Appendix A: Stress-Based Plasticity Constitutive Equations .................................................. 237

12.5.1 General ............................................................................................................................. 237

12.5.2 Relationship Between Stress and Strain in Elastic Region .............................................. 239

12.5.3 Yield Criterion ................................................................................................................. 240

12.5.4 Plastic Strain Increment ................................................................................................... 242

12.5.5 Stress Increment - Strain Increment Relation in Plastic Region ...................................... 246

12.6 Appendix B: Deformation Matrix ........................................................................................... 247

12.7 References ............................................................................................................................... 248

CHAPTER 13 COLLAPSE ANALYSIS OF SHIP HULLS ........................................................... 251

13.1 Introduction ............................................................................................................................. 251

13.2 Hull Structural Analysis Based on the Plastic Node Method .................................................. 252

13.2.1 Beam-Column Element .................................................................................................... 252

13.2.3 Shear Panel Element ........................................................................................................ 257

13.2.4 Non-Linear Spring Element ............................................................................................. 257

13.2.5 Tension Tearing Rupture .................................................................................................. 257

13.3 Analytical Equations for Hull Girder Ultimate Strength ......................................................... 260

13.3.1 Ultimate Moment Capacity Based on Elastic Section Modulus ...................................... 260

13.3.2 Ultimate Moment Capacity Based on Fully Plastic Moment ........................................... 261

12.3.4 Elastic-Plastic Stiffness Equation for Elements ............................................................... 235

13.2.2 Attached Plating Element ................................................................................................. 254

13.2.6 Computational Procedures ............................................................................................... 259

13.3.3 Proposed Ultimate Strength Equations ............................................................................ 263

13.4 Modified Smith Method Accounting for Corrosion and Fatigue Defects ............................... 264

13.4.1 Tensile and Comer Elements ........................................................................................... 265

13.4.2 Compressive Stiffened Panels .......................................................................................... 265

13.4.3 Crack Propagation Prediction ........................................................................................... 266

13.4.4 Corrosion Rate Model ...................................................................................................... 267

13.5 Comparisons of Hull Girder Strength Equations and Smith Method ...................................... 269

13.6 Numerical Examples Using the Proposed Plastic Node Method ............................................. 271

13.6.1 Collapse of a Stiffened Plate ............................................................................................ 271

xii Contents

13.6.2 Collapse of an Upper Deck Structure ............................................................................... 273

13.6.3 Collapse of Stiffened Box Girders ................................................................................... 274

13.6.4 Ultimate Longitudinal Strength of Hull Girders .............................................................. 276

13.6.5 Quasi-Static Analysis of a Side Collision ........................................................................ 278

13.7 Conclusions ............................................................................................................................. 279

13.8 References ............................................................................................................................... 280

CHAPTER 14 OFFSHORE STRUCTURES UNDER IMPACT LOADS .................................... 285

14.1 General ..................................................................................................................................... 285

14.2 Finite Element Formulation ..................................................................................................... 286

14.2.1 Equations of Motion ......................................................................................................... 286

14.2.3 Beam-Column Element for Modeling of the Struck Structure ......................................... 287

14.2.4 Computational Procedure ................................................................................................. 287

14.3 Collision Mechanics ................................................................................................................ 289

14.3.1 Fundamental Principles .................................................................................................... 289

14.3.2 Conservation of Momentum ............................................................................................ 289

14.3.3 Conservation of Energy .................................................................................................... 290

14.4 Examples ................................................................................................................................. 291

14.4.1 Mathematical Equations for Impact Forces and Energies in ShiplPlafform Collisions ... 29 1

14.4.2 Basic Numerical Examples .............................................................................................. 292

14.4.3 Application to Practical Collision Problems .................................................................... 298

14.5 Conclusions ............................................................................................................................. 303

14.6 References ............................................................................................................................... 303

CHAPTER 15 OFFSHORE STRUCTURES UNDER EARTHQUAKE LOADS ............ 305

15.1 General ..................................................................................................................................... 305

15.2 Earthquake Design as per API RP2A ...................................................................................... 305

15.3 Equations and Motion .............................................................................................................. 307

15.3.1 Equation of Motion .......................................................................................................... 307

15.3.2 Nonlinear Finite Element Model ...................................................................................... 308

15.3.3 Analysis Procedure ........................................................................................................... 308

15.4 Numerical Examples ................................................................................................................ 308

15.5 Conclusions ............................................................................................................................. 313

15.6 References ............................................................................................................................... 314

14.2.2 Load-Displacement Relationship ofthe Hit Member ...................................................... 286

Part 111: Fatigue and Fracture

CHAPTER 16 MECHANISM OF FATIGUE AND FRACTURE ................................................ 317

16.1 Introduction ............................................................................................................................. 317

16.2 Fatigue Overview .................................................................................................................... 317

16.3 Stress-Controlled Fatigue ........................................................................................................ 318

16.4 Cumulative Damage for Variable Amplitude Loading ............................................................ 320

16.5 Strain-Controlled Fatigue ........................................................................................................ 321

16.6 Fracture Mechanics in Fatigue Analysis .................................................................................. 323

16.7 Examples ................................................................................................................................. 325

16.8 References ............................................................................................................................... 326

CHAPTER 17 FATIGUE CAPACITY ... ......................................................................................... 329

17.1 S-N Curves .............................................................................................................................. 329

17.1.1 General ............................................................................................................................. 329

17.1.2 Effect of Plate Thickness ................................................................................................. 33 1