Design Aids of Offshore Structures Under Special Environmental Loads including Fire Resistance

344 Pages·2018·6.72 MB·English

by  Srinivasan Chandrasekaran

Ocean Engineering & Oceanography 11
Srinivasan Chandrasekaran
Gaurav Srivastava
Design Aids of Offshore
Structures Under
Special Environmental
Loads Including Fire
Resistance
Ocean Engineering & Oceanography
Volume 11
Series editors
Manhar R. Dhanak, Florida Atlantic University SeaTech, Dania Beach, USA
Nikolas I. Xiros, New Orleans, USA
More information about this series at http://www.springer.com/series/10524
Srinivasan Chandrasekaran
Gaurav Srivastava
Design Aids of Offshore
Structures Under Special
Environmental Loads
Including Fire Resistance
123
Srinivasan Chandrasekaran Gaurav Srivastava
Department ofOcean Engineering Department ofCivil Engineering
Indian Institute of Technology Madras Indian Institute of Technology Gandhinagar
Chennai, Tamil Nadu Gandhinagar, Gujarat
India India
ISSN 2194-6396 ISSN 2194-640X (electronic)
Ocean Engineering &Oceanography
ISBN978-981-10-7607-7 ISBN978-981-10-7608-4 (eBook)
https://doi.org/10.1007/978-981-10-7608-4
LibraryofCongressControlNumber:2017960286
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Preface
The book titled Design Aids of Offshore Structures under Special Environmental
Loads including Fire Resistance is focused to address analysis and design of
structural members in general and offshore structures, in particular. Offshore
structuresposseshighnoveltybytheirform-dominance,whoseanalysisanddesign
aredifferentfromotherconventionalcivilengineeringstructures.Primaryobjective
ofthistextbookistoencapsulatetheimportanttechnicalfundamentals ofanalysis
and design under special loads.
This book covers a descriptive explanation on different types of offshore
structures, with special focus to their structural action under the encountered
environmentalloads.Specialloadsnamelyiceloads,loadsthatarisefromspringing
andringingwaves,blastloadsandfireloadsarepresentedindetail.Asapplication
of loads on members of offshore structures invoke unsymmetrical bending, con-
ceptsofadvancedstructuralanalysesarecoveredindetailandexplainedwithmore
numericalexamples.Analysisanddesignofcranehooks,forexample,canbeseen
as a distinct contribution to this section.
Safety of offshore platforms against fire needs to be ascertained due to their
strategic importance. In addition to the deliberations on fire-resistant design of
structural members, principles of fire and explosion safety are also presented in
detail. A descriptive chapter on analysis and design of members in fire presents
fundamental properties of steel and concrete under elevated temperatures and their
significance in design. Numerical examples of assessment of fire resistance of
structural members will help understand the presented concepts.
Contents of this book are carefully derived based on the extensive literature
reviewedwiththefocustomakeitsimpleandpresentableinaclass-roommodeof
teaching.Valuablecontributionsmadebyotherauthorsinthisimportantdomainof
structural engineering are sincerely acknowledged. We continue to believe that a
text book on Design aids of offshore structures is possible only with both the
industrialandacademicinputs.Whileauthorsagreethatsubjectmatterofthebook
is not self-contained but with some details missing, basic purpose is not to be
completebuttoprovideastartingpointforthosewhowishtolearnthissubjectwith
a relative degree of convenience. We thank our teachers, friends and colleagues
v
vi Preface
who continue to teach us the fundamentals of analysis and design under special
environmental loads and fire-resistance.
We sincerely acknowledge the administrative support extended by Centre of
Continuing Education, Indian Institute of Technology Madras and Indian Institute
of Technology Gandhinagar during the writing of this text book. We continue to
acknowledge our families, who provided support and encouragement throughout
writing this book.
Tamil Nadu, India Srinivasan Chandrasekaran
Gujarat, India Gaurav Srivastava
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Novelty of Offshore Structures . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Fixed Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Compliant Platforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.1 Guyed Towers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.2 Articulated Towers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.3 Tension Leg Platform. . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4 Single Point Anchor Reservoir (SPAR) . . . . . . . . . . . . . . . . . . . 11
1.5 Floating Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.5.1 Floating Production Storage and Offloading Platform
(FPSO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.5.2 Semisubmersible . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.5.3 Jack-up Rigs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.5.4 Drill Ships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.6 New-Generation Offshore Platforms. . . . . . . . . . . . . . . . . . . . . . 17
1.7 Buoyant Leg Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.8 Triceratops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.9 Regasification Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.10 Environmental Loads and Complexities . . . . . . . . . . . . . . . . . . . 22
1.11 Wave Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.11.1 Wheeler’s Modifications. . . . . . . . . . . . . . . . . . . . . . . . 25
1.11.2 Chakrabarti’s Modifications . . . . . . . . . . . . . . . . . . . . . 25
1.11.3 Pierson-Moskowitz (PM) Spectrum . . . . . . . . . . . . . . . . 26
1.11.4 Modified PM Spectrum . . . . . . . . . . . . . . . . . . . . . . . . 27
1.11.5 ISSC Spectrum (International Ship Structures
Congress) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.11.6 JONSWAP Spectrum(Joint North Sea Wave Project)... 27
1.12 Wind Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.12.1 Davenport Spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . . 31
vii
viii Contents
1.12.2 Harris Spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.12.3 Kaimal Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.12.4 API(2000) Spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1.13 Ice Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.14 Current Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.15 Analysis Under Seismic Loads . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.16 Analysis Under Distinctly High Sea Waves . . . . . . . . . . . . . . . . 38
1.16.1 Analytical Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
1.17 Springing and Ringing Waves. . . . . . . . . . . . . . . . . . . . . . . . . . 47
1.18 Blast Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
1.18.1 Protected Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
1.18.2 Quantification of Blast Loads . . . . . . . . . . . . . . . . . . . . 53
1.19 Fire Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
1.19.1 Types of Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
1.20 Research Study 1: Dynamic Analysis of Buoyant Leg
Storage and Regasification Platforms (BLSRPs) . . . . . . . . . . . . . 55
1.21 Illustrated Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
1.22 Examples on Probability Distributions of Continuous
Random Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
1.22.1 Normal Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
1.22.2 Exponential Distribution. . . . . . . . . . . . . . . . . . . . . . . . 63
1.22.3 Erlang Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
1.22.4 Gamma Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . 65
1.22.5 Weibull Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . 66
1.22.6 Lognormal Distribution . . . . . . . . . . . . . . . . . . . . . . . . 66
2 Advanced Structural Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.1 Unsymmetrical Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.2 Example Problems on Unsymmetrical Bending. . . . . . . . . . . . . . 78
2.3 Shear Center. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
2.4 Example Problems on Shear Center. . . . . . . . . . . . . . . . . . . . . . 90
2.5 Curved Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
2.5.1 Curved Beams with Small Initial Curvature. . . . . . . . . . 101
2.5.2 Deflection of Curved Beam with Small Initial
Curvature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
2.5.3 Curved Beam with Large Initial Curvature. . . . . . . . . . . 104
2.5.4 Circular Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . 109
2.5.5 Rectangular Cross Section . . . . . . . . . . . . . . . . . . . . . . 113
2.5.6 T Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
2.5.7 I Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
2.5.8 Triangular Cross Section. . . . . . . . . . . . . . . . . . . . . . . . 117
2.5.9 Trapezoidal Cross Section. . . . . . . . . . . . . . . . . . . . . . . 119
2.6 Simplified Equations to Estimate Stresses. . . . . . . . . . . . . . . . . . 120
2.7 Example Problems in Curved Beams . . . . . . . . . . . . . . . . . . . . . 121
Contents ix
2.8 Marine Risers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
2.8.1 Low-Pressure Risers. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
2.8.2 High-Pressure Drilling Riser . . . . . . . . . . . . . . . . . . . . . 127
2.8.3 Flexible Risers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
2.8.4 Top Tensioned Risers (TTR). . . . . . . . . . . . . . . . . . . . . 127
2.9 Members Under Vortex-Induced Vibration (VIV). . . . . . . . . . . . 130
2.10 Research Case Study: Effect of Suppression System
on VIV of Spar Cylinder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
3 Fire Safety in Offshore Structures . . . . . . . . . . . . . . . . . . . . . . . . . . 159
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
3.2 Fire and Explosion Characteristics. . . . . . . . . . . . . . . . . . . . . . . 161
3.3 Best Practices in Fire Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
3.3.1 Common Mistakes in Fire Accidents. . . . . . . . . . . . . . . 164
3.4 Fire Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
3.5 Classification of Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
3.5.1 Pool Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
3.5.2 Jet Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
3.5.3 Fire Ball . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
3.5.4 Flash Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
3.5.5 Minimum Ignition Energy . . . . . . . . . . . . . . . . . . . . . . 167
3.6 Fire Protection in Offshore Platforms. . . . . . . . . . . . . . . . . . . . . 167
3.6.1 Complications in the Fire-Resistant Design . . . . . . . . . . 169
3.6.2 Firefighting Equipments . . . . . . . . . . . . . . . . . . . . . . . . 170
3.7 Objectives of Fire Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
3.8 Fire Behavior and Development . . . . . . . . . . . . . . . . . . . . . . . . 171
3.8.1 Fire Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
3.9 Egress and Human Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
3.10 Fire Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
3.11 Detection and Fire Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
3.11.1 Active Control of Fire . . . . . . . . . . . . . . . . . . . . . . . . . 175
3.11.2 Passive Control of Fire. . . . . . . . . . . . . . . . . . . . . . . . . 175
3.11.3 Compartmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
3.12 Fire Load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
3.13 Combustion of Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
3.14 Initiation of Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
3.15 Open Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
3.16 t-Squared Fire Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
3.17 Compartment Fire. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
3.17.1 Pre-flashover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
3.17.2 Flashover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
3.17.3 Post-flashover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
3.18 Fire Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188