Cover
List of Figures
List of Tables
Foreword by Professor Purnendu K. Das
Foreword by Dr. Atmanand N.D.
Series Preface
Preface
1 Common Compliant Platforms
1. 1.1 Introduction
2. 1.2 Tension Leg Platforms
3. 1.3 Guyed Tower and Articulated Tower
4. 1.4 Floating Structures
5. 1.5 Response Control Strategies
6. 1.6 Tuned Mass Dampers
7. 1.7 Response Control of Offshore Structures
8. 1.8 Response Control of TLPs Using TMDs: Experimental Investigations
9. 1.9 Articulated Towers
10. 1.10 Response Control of ATs: Analytical Studies
11. 1.11 Response Control of ATs: Experimental Studies
2 Buoyant Leg Storage and Regasification Platforms
1. 2.1 Background Literature
2. 2.2 Experimental Setup
3. 2.3 Experimental Investigations
4. 2.4 Numerical Studies
5. 2.5 Critical Observations
6. 2.6 Stability Analysis of the BLSRP
7. 2.7 Fatigue Analysis of the BLSRP
3 New‐Generation Platforms: Offshore Triceratops
1. 3.1 Introduction
2. 3.2 Environmental Loads
3. 3.3 Fatigue Analysis of Tethers
4. 3.4 Response to Regular Waves
5. 3.5 Response to Random Waves
6. 3.6 Response to Combined Actions of Wind, Waves, and Current
7. 3.7 Summary
4 Triceratops Under Special Loads
1. 4.1 Introduction
2. 4.2 Continuous Ice Crushing
3. 4.3 Response to Continuous Ice Crushing
4. 4.4 Response to Impact Loads
5. 4.5 Deck Response to Hydrocarbon Fires
6. 4.6 Summary
5 Offshore Triceratops: Recent Advanced Applications
1. 5.1 Introduction
2. 5.2 Wind Turbines
3. 5.3 Wind Power
4. 5.4 Evolution of Wind Turbines
5. 5.5 Conceptual Development of the Triceratops‐Based Wind Turbine
6. 5.6 Support Systems for Wind Turbines
7. 5.7 Wind Turbine on a Triceratops
8. 5.8 Response of a Triceratops‐Based Wind Turbine to Waves
9. 5.9 Stiffened Triceratops
10. 5.10 Triceratops with Elliptical Buoyant Legs
11. 5.11 Summary
Model Exam Paper 1
Model Exam Paper 1: KEY
Model Exam Paper 2
Model Exam Paper 2: KEY
Model Exam Paper 3
Model Exam Paper 3: KEY
References
Index
End User License Agreement

List of Tables

Chapter 1
1. Table 1.1 Major fixed platforms constructed worldwide (as of 2017).
2. Table 1.2 Tension leg platforms constructed worldwide.
3. Table 1.3 Properties of a TMD in the model and prototype (scale 1 : 100).
4. Table 1.4 Results of free oscillation tests of the TLP model.
5. Table 1.5 RMS value of surge responses in the presence of random waves.
6. Table 1.6 RMS value of pitch responses in the presence of random waves.
7. Table 1.7 Mechanical properties of the Perspex material used for the model.
Chapter 2
1. Table 2.1 Structural details of the BLSRP.
2. Table 2.2 Natural periods and damping ratios.
3. Table 2.3 Maximum response of the BLSRP model (0°, 0.1 m).
4. Table 2.4 Maximum response amplitudes (numerical studies; 6 m wave height).
5. Table 2.5 Geometric properties of the BLSRP for the stability study.
6. Table 2.6 Maximum tension amplitude in the tethers in postulated failure case...
7. Table 2.7 Mathieu parameters in postulated failure cases.
8. Table 2.8 Fatigue life (rounded off) of tethers under eccentric loading.
Chapter 3
1. Table 3.1 Characteristics of random sea conditions.
2. Table 3.2 Comparison of responses to regular waves.
3. Table 3.3 Deck response to different sea conditions.
4. Table 3.4 Comparison of deck responses to high sea conditions.
5. Table 3.5 Tension variation and service life of tethers of buoyant leg 1.
6. Table 3.6 Characteristics of sea conditions (Jain and Chandrasekaran 2004).
7. Table 3.7 Tether tension variation with combined actions of wind, waves, and ...
Chapter 4
1. Table 4.1 Mechanical properties of marine DH36 steel (Cho et al. 2015).
2. Table 4.2 Ice sea conditions.
3. Table 4.3 Deck response to different sea conditions.
4. Table 4.4 Deck response to open water and ice‐covered load cases.
5. Table 4.5 Collision speed and impact duration (Syngellakis and Balaji 1989).
6. Table 4.6 Mechanical properties of DH36 steel at a 0.001/s strain rate (Kim e...
Chapter 5
1. Table 5.1 Properties of the triceratops‐based wind turbine.
2. Table 5.2 Variation in RAO with changes in the wave heading angle.
3. Table 5.3 Service life estimation of the triceratops.
4. Table 5.4 Geometric parameters of the offshore triceratops.
5. Table 5.5 Mass properties of the triceratops.
6. Table 5.6 Response of the triceratops given rough sea conditions.

List of Illustrations

Chapter 1
1. Figure 1.1 A typical tension leg platform.
2. Figure 1.2 TLP mechanics.
3. Figure 1.3 Active control strategy.
4. Figure 1.4 Semi‐active control strategy.
5. Figure 1.5 Block diagram for passive control strategy.
6. Figure 1.6 Pall friction damper.
7. Figure 1.7 Metallic yield damper.
8. Figure 1.8 Viscous fluid damper.
9. Figure 1.9 Tuned liquid damper: (a) circular; (b) rectangular.
10. Figure 1.10 Tuned liquid column damper.
11. Figure 1.11 Tuned mass damper.
12. Figure 1.12 Schematic diagram of an idealized system.
13. Figure 1.13 Schematic diagram of a spring‐mass system with a TMD.
14. Figure 1.14 Mass used in the TMD.
15. Figure 1.15 Response of a TLP and TMD (μ = 1.5%).
16. Figure 1.16 Response of a TLP and TMD (μ = 3.0%).
17. Figure 1.17 Surge RAO of a TMD.
18. Figure 1.18 Comparison of surge response (H_S = 8 m; T_P = 12 seconds).
19. Figure 1.19 Comparison of surge response (H_S = 8 m; T_P = 16 seconds).
20. Figure 1.20 Comparison of surge response (H_S = 8 m; T_P = 20 seconds).
21. Figure 1.21 Comparison of surge response (H_S = 8 m; T_P = 32.5 seconds).
22. Figure 1.22 Comparison of pitch response (H_S = 8 m; T_P = 12 seconds).
23. Figure 1.23 Comparison of pitch response (H_S = 8 m; T_P = 16 seconds).
24. Figure 1.24 Comparison of pitch response (H_S = 8 m; T_P = 20 seconds).
25. Figure 1.25 Comparison of pitch response (H_S = 8 m; T_P = 32.5 seconds).
26. Figure 1.26 Articulated tower.
27. Figure 1.27 Analytical model.
28. Figure 1.28 Variation of responses for different frequency ratios.
29. Figure 1.29 Variation of responses for different frequency ratios with a TMD...
30. Figure 1.30 Variation of responses for different frequency and mass ratios w...
31. Figure 1.31 Geometric details of the model.
32. Figure 1.32 Model of a TMD.
33. Figure 1.33 Free‐vibration time history.
34. Figure 1.34 Surge response of a MLAT without a TMD.
35. Figure 1.35 Surge RAO for TMD‐1.
36. Figure 1.36 Surge RAO for TMD‐2.
37. Figure 1.37 Surge RAO for TMD‐3.
38. Figure 1.38 Comparison of RAOs for 3 cm wave height.
39. Figure 1.39 Comparison of RAOs for 5 cm wave height.
40. Figure 1.40 Comparison of RAOs for 7 cm wave height.
Chapter 2
1. Figure 2.1 Schematic diagram of the BLSRP installed in a wave flume.
2. Figure 2.2 Experimental setup and arrangements: (a) side view; (b) hinged jo...
3. Figure 2.3 Orientation of the BLSRP for the wave heading angle.
4. Figure 2.4 Response of the BLSRP (0°, 0.1 m wave height).
5. Figure 2.5 Numerical model of the BLSRP.
6. Figure 2.6 Response of the BLSRP (30°, 15 m).
7. Figure 2.7 Tether tension variations in mooring lines.
8. Figure 2.8 Power spectral density plots of buoyant leg 1 (0°, 6 m, 10 second...
9. Figure 2.9 Power spectral density plots of the deck (0°, 6 m, 10 seconds).
10. Figure 2.10 Numerical model of the BLSRP (normal case).
11. Figure 2.11 Numerical model of the BLSRP with postulated failure.
12. Figure 2.12 Dynamic tether tension variation in postulated failure cases.
13. Figure 2.13 Mathieu stability for the BLSRP in postulated failure cases.
Chapter 3
1. Figure 3.1 Typical regular wave profile (H = 2 m, T = 5 s).
2. Figure 3.2 PM spectrum for different sea conditions.
3. Figure 3.3 Two‐dimensional random wave profile (Wang and Isberg 2015).
4. Figure 3.4 API spectrum plot for different wind velocities.
5. Figure 3.5 Wind‐generated current velocity profile.
6. Figure 3.6 Service life estimation methodology.
7. Figure 3.7 Triceratops model.
8. Figure 3.8 Experimental model of a stiffened triceratops.
9. Figure 3.9 Plan of the triceratops.
10. Figure 3.10 RAOs of the deck and buoyant legs with regular waves.
11. Figure 3.11 Deck response given different wave heading angles.
12. Figure 3.12 Tether tension variation in rough sea conditions.
13. Figure 3.13 Deck surge and heave PSD plots in very high sea conditions.
14. Figure 3.14 Pitch response of the deck and buoyant legs in very high sea con...
15. Figure 3.15 Maximum deck response in very high sea conditions.
16. Figure 3.16 Tether tension spectrum with very high sea conditions.
17. Figure 3.17 Maximum tether tension in very high sea conditions.
18. Figure 3.18 Deck response with high sea conditions (w – waves, w + w – waves...
19. Figure 3.19 Phase plots in the surge DOF with very high sea conditions.
20. Figure 3.20 Buoyant leg response with high sea conditions.
21. Figure 3.21 Tension spectrum with very high sea conditions.
Chapter 4
1. Figure 4.1 Random ice force and vibration of the structure.
2. Figure 4.2 True stress–strain curve of AH36 grade steel.
3. Figure 4.3 Different shapes of indenters.
4. Figure 4.4 Time–temperature curves for different fire conditions.
5. Figure 4.5 Reduction factors for yield strength, proportional limits, and li...
6. Figure 4.6 Variations in the thermal conductivity of carbon steel.
7. Figure 4.7 Variations in the specific heat of carbon steel.
8. Figure 4.8 Variations in the thermal strain of carbon steel.
9. Figure 4.9 Spectral density plot given different ice velocities.
10. Figure 4.10 Spectral density plot given different ice forces.
11. Figure 4.11 Ice force–time history.
12. Figure 4.12 PSD plots for normal ice sea conditions with ice load on two buo...
13. Figure 4.13 PSD plots of tether tension variation in normal sea conditions....
14. Figure 4.14 Total deck response for different ice thicknesses.
15. Figure 4.15 Total deck response for different ice crushing strengths.
16. Figure 4.16 Total deck response for different ice velocities.
17. Figure 4.17 PSD plots of the deck in open water and ice‐covered load cases....
18. Figure 4.18 Methodology of impact analysis.
19. Figure 4.19 Numerical model of buoyant legs and indenters.
20. Figure 4.20 Force versus nondimensional deformation curve.
21. Figure 4.21 Deck surge responses for impact loads on buoyant leg 1.
22. Figure 4.22 Force–deformation curves for different indenter sizes.
23. Figure 4.23 Force–deformation curves for different impact locations.
24. Figure 4.24 Force–deformation curves for different indenter shapes.
25. Figure 4.25 Force–deformation curves for different numbers of stringers.
26. Figure 4.26 Force–deformation curve of buoyant legs at different temperature...
27. Figure 4.27 Deck plate of a triceratops.
28. Figure 4.28 Scale deck plate model.
29. Figure 4.29 Hydrocarbon fire cases.
30. Figure 4.30 Temperature variations in plates and stiffeners.
Chapter 5
1. Figure 5.1 Numerical model of a triceratops with a wind turbine.
2. Figure 5.2 Pitch RAO of the triceratops.
3. Figure 5.3 PSD plot of the surge free‐decay response.
4. Figure 5.4 PSD plot of the roll free‐decay response.
5. Figure 5.5 Frequency response to operable and parked conditions.
6. Figure 5.6 PSD plots for different DOF.
7. Figure 5.7 Dynamic tether tension variation.
8. Figure 5.8 Plan and elevation of a stiffened buoyant leg.
9. Figure 5.9 Fabricated model of a stiffened buoyant leg.
10. Figure 5.10 Fabricated model of a ball joint.
11. Figure 5.11 Surge, heave, and pitch RAOs of the deck and buoyant legs with 0...
12. Figure 5.12 Surge, heave, and pitch RAOs of the deck and buoyant legs with 9...
13. Figure 5.13 Surge, heave, and pitch RAOs of the deck and buoyant legs with 1...
14. Figure 5.14 Effect of wave direction on the stiffened triceratops.
15. Figure 5.15 Cross section of the buoyant legs.
16. Figure 5.16 Plan view of the triceratops with circular and elliptical buoyan...
17. Figure 5.17 Total force–time history, given high sea conditions.

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Library of Congress Cataloging‐in‐Publication Data

Names: Chandrasekaran, Srinivasan, author. | Nagavinothini, R., 1991– author.
Title: Offshore compliant platforms : analysis, design, and experimental studies / Srinivasan Chandrasekaran, Department of Ocean Engineering, Indian Institute of Technology Madras, Tamil Nadu, India, R. Nagavinothini, Department of Structures for Engineering and Architecture, University of Naples Federico II, Naples, Italy.
Description: First edition. | Hoboken, NJ : John Wiley & Sons, Inc., 2020. | Series: Wiley‐ASME Press Series | Includes bibliographical references and index.
Identifiers: LCCN 2019050441 (print) | LCCN 2019050442 (ebook) | ISBN 9781119669777 (hardback) | ISBN 9781119669784 (adobe pdf) | ISBN 9781119669807 (epub)
Subjects: LCSH: Compliant platforms.
Classification: LCC TC1700 .C44 2020 (print) | LCC TC1700 (ebook) | DDC 627/.98–dc23
LC record available at https://lccn.loc.gov/2019050441
LC ebook record available at https://lccn.loc.gov/2019050442

List of Figures

1.1	A typical tension leg platform.
1.2	TLP mechanics.
1.3	Active control strategy.
1.4	Semi‐active control strategy.
1.5	Block diagram for passive control strategy.
1.6	Pall friction damper.
1.7	Metallic yield damper.
1.8	Viscous fluid damper.
1.9	Tuned liquid damper: (a) circular; (b) rectangular.
1.10	Tuned liquid column damper.
1.11	Tuned mass damper.
1.12	Schematic diagram of an idealized system.
1.13	Schematic diagram of a spring‐mass system with a TMD.
1.14	Mass used in the TMD.
1.15	Response of a TLP and TMD (μ = 1.5%).
1.16	Response of a TLP and TMD (μ = 3.0%).
1.17	Surge RAO of a TMD.
1.18	Comparison of surge response (HS = 8 m; TP = 12 seconds).
1.19	Comparison of surge response (HS = 8 m; TP = 16 seconds).
1.20	Comparison of surge response (HS = 8 m; TP = 20 seconds).
1.21	Comparison of surge response (HS = 8 m; TP = 32.5 seconds).
1.22	Comparison of pitch response (HS = 8 m; TP = 12 seconds).
1.23	Comparison of pitch response (HS = 8 m; TP = 16 seconds).
1.24	Comparison of pitch response (HS = 8 m; TP = 20 seconds).
1.25	Comparison of pitch response (HS = 8 m; TP = 32.5 seconds).
1.26	Articulated tower.
1.27	Analytical model.
1.28	Variation of responses for different frequency ratios.
1.29	Variation of responses for different frequency ratios with a TMD.
1.30	Variation of responses for different frequency and mass ratios with a TMD.
1.31	Geometric details of the model.
1.32	Model of a TMD.
1.33	Free‐vibration time history.
1.34	Surge response of a MLAT without a TMD.
1.35	Surge RAO for TMD‐1.
1.36	Surge RAO for TMD‐2.
1.37	Surge RAO for TMD‐3.
1.38	Comparison of RAOs for 3 cm wave height.
1.39	Comparison of RAOs for 5 cm wave height.
1.40	Comparison of RAOs for 7 cm wave height.
2.1	Schematic diagram of the BLSRP installed in a wave flume.
2.2	Experimental setup and arrangements: (a) side view; (b) hinged joint; (c) roller at the base plate for guiding the mooring line; (d) load cell; (e) ratchet mechanism for adjusting the tension; (f) plan arrangement.
2.3	Orientation of the BLSRP for the wave heading angle.
2.4	Response of the BLSRP (0°, 0.1 m wave height).
2.5	Details of the hinged joint in the numeric model.
2.6	Response of the BLSRP (30°, 15 m).
2.7	Tether tension variations in mooring lines.
2.8	Power spectral density plots of buoyant leg 1 (0°, 6 m, 10 seconds).
2.9	Power spectral density plots of the deck (0°, 6 m, 10 seconds).
2.10	Numerical model of the BLSRP (normal case).
2.11	Numerical model of the BLSRP with postulated failure.
2.12	Dynamic tether tension variation in postulated failure cases.
2.13	Mathieu stability for the BLSRP in postulated failure cases.
3.1	Typical regular wave profile (H = 2 m, T = 5 s).
3.2	PM spectrum for different sea conditions.
3.3	Two‐dimensional random wave profile.
3.4	API spectrum plot for different wind velocities.
3.5	Wind‐generated current velocity profile.
3.6	Service life estimation methodology.
3.7	Triceratops model.
3.8	Experimental model of a stiffened triceratops.
3.9	Plan of the triceratops.
3.10	RAOs of the deck and buoyant legs with regular waves.
3.11	Deck response given different wave heading angles.
3.12	Tether tension variation in rough sea conditions.
3.13	Deck surge and heave PSD plots in very high sea conditions.
3.14	Pitch response of the deck and buoyant legs in very high sea conditions.
3.15	Maximum deck response in very high sea conditions.
3.16	Tether tension spectrum with very high sea conditions.
3.17	Maximum tether tension in very high sea conditions.
3.18	Deck response with high sea conditions (w – waves, w + w – waves+wind, w + w + c – waves+wind+current).
3.19	Phase plots in the surge DOF with very high sea conditions.
3.20	Buoyant leg response with high sea conditions.
3.21	Tension spectrum with very high sea conditions.
4.1	Random ice force and vibration of the structure.
4.2	True stress–strain curve of AH36 grade steel.
4.3	Different shapes of indenters.
4.4	Time–temperature curves for different fire conditions.
4.5	Reduction factors for yield strength, proportional limits, and linear elastic range for carbon steel.
4.6	Variations in the thermal conductivity of carbon steel.
4.7	Variations in the specific heat of carbon steel.
4.8	Variations in the thermal strain of carbon steel.
4.9	Spectral density plot given different ice velocities.
4.10	Spectral density plot given different ice forces.
4.11	Ice force–time history.
4.12	PSD plots for normal ice sea conditions with ice load on two buoyant legs.
4.13	PSD plots of tether tension variation in normal sea conditions.
4.14	Total deck response for different ice thicknesses.
4.15	Total deck response for different ice crushing strengths.
4.16	Total deck response for different ice velocities.
4.17	PSD plots of the deck in open water and ice‐covered load cases.
4.18	Methodology of impact analysis.
4.19	Numerical model of buoyant legs and indenters.
4.20	Force versus nondimensional deformation curve.
4.21	Deck surge responses for impact loads on buoyant leg 1.
4.22	Force–deformation curves for different indenter sizes.
4.23	Force–deformation curves for different impact locations.
4.24	Force–deformation curves for different indenter shapes.
4.25	Force–deformation curves for different numbers of stringers.
4.26	Force–deformation curve of buoyant legs at different temperatures.
4.27	Deck plate of a triceratops.
4.28	Scale deck plate model.
4.29	Hydrocarbon fire cases.
4.30	Temperature variations in plates and stiffeners.
5.1	Numerical model of a triceratops with a wind turbine.
5.2	Pitch RAO of the triceratops.
5.3	PSD plot of the surge free‐decay response.
5.4	PSD plot of the roll free‐decay response.
5.5	Frequency response to operable and parked conditions.
5.6	PSD plots for different DOF.
5.7	Dynamic tether tension variation.
5.8	Plan and elevation of a stiffened buoyant leg.
5.9	Fabricated model of a stiffened buoyant leg.
5.10	Fabricated model of a ball joint.
5.11	Surge, heave, and pitch RAOs of the deck and buoyant legs with 0° incident waves.
5.12	Surge, heave, and pitch RAOs of the deck and buoyant legs with 90° waves.
5.13	Surge, heave, and pitch RAOs of the deck and buoyant legs with 180° waves.
5.14	Effect of wave direction on the stiffened triceratops.
5.15	Cross section of the buoyant legs.
5.16	Plan view of the triceratops with circular and elliptical buoyant legs.
5.17	Total force–time history, given high sea conditions.

Foreword by Dr. Atmanand N.D.

The use of renewable energies is vital for addressing issues due to global warming and climate change. But the cost of production of renewable energy has not hit an all‐time low as yet, and oil and gas continue to be the major sources of energy.

In the recent past, offshore oil drilling and production platforms have begun moving toward ultra‐deep water due to the depletion of oil and gas resources near shore. In addition, the arctic region is opening for new offshore platforms. This necessitates a novel geometric form with reduced response to extreme waves and, in turn, the extreme loading conditions that prevail in ultra‐deep water. Compliant offshore platforms are highly popular due to their form‐‐dominant design characteristics. However, their significant hull motion in deepwater conditions and high sea conditions leads to a need for alternate design procedures, because the present ones are not suitable for ultra‐deep water. Detailed analysis and design procedures for new‐generation offshore platforms are frequently debated in conference proceedings. But this book demystifies the technological know‐how by presenting a lucid explanation that is useful and innovative. For example, the discussion of a new methodology for the dynamic analysis of a triceratops under ice loads in ice‐covered regions, with detailed parametric studies, is noteworthy. Such structures are prone to accidental loads arising due to fires and ship–platform collisions, so both designers and researchers should be familiar with the detailed dynamic analysis under such loads. The comprehensive picture presented in this book of the dynamic response behavior of this novel platform under different types of loads is scarce elsewhere in the literature.

This book will serve as a resource for understanding the basic structural behavior of new‐generation complex offshore platforms and will help graduate students understand analysis methodologies that otherwise would have to be painstakingly collected from many publications. In addition, this book will be useful for practicing engineers and research scholars who wish to understand the response behavior of structures with novel geometry under combinations of extreme loads.

The principal author, Srinivasan Chandrasekaran, is a well‐known academician and has authored 14 textbooks in the highly specialized area of offshore engineering. His web‐based courses on offshore structural engineering are very popular and serve as reference material to teach this complex subject at both the undergraduate and post‐graduate levels of engineering programs in various disciplines including civil, mechanical, aerospace, naval architecture, etc. I am sure any offshore engineer will find this book to be a wealth of resources.

Dr. Atmanand N.D.
Director, Chair IOCINDIO (UNESCO)
National Institute of Ocean Technology
Chennai
India

Preface

This book, Offshore Compliant Platforms: Analysis, Design, and Experimental Studies, describes detailed analysis and design procedures for compliant offshore structures, with a special focus on new‐generation platforms like the triceratops and buoyant leg storage and regasification platforms. While the conceptual development of conventional platforms like tension leg platforms (TLPs), spar platforms, and articulated towers is presented briefly, the detailed descriptions of the design and development of new‐generation platforms discussed in the book are highly novel and still in the preliminary stages of study in the existing literature.

Compliant offshore platforms are favorable candidates for deepwater oil and gas production systems due to their form‐dominant design characteristics. But significant compliancy causing flexible motion in the horizontal plane requires special attention from designers because it poses critical challenges when platforms are commissioned in ultra‐deep water. Therefore, a novel geometric form with reduced responses is a vital necessity to accommodate extreme loading.

This book presents a detailed analysis and design of one such novel platform: the triceratops. The authors believe that it will serve as a good reference guide for the effective design of triceratops platforms, as the clear numerical and experimental studies presented in the book will help readers understand the platforms' dynamic response behavior. A new methodology for the dynamic analysis of a triceratops under ice loads in ice‐covered regions is also explained with detailed parametric studies. Offshore platforms are also prone to accidental loads arising due to fires and ship–platform collisions; the detailed dynamic analysis under such loads that is presented in the book will be of great interest to both researchers and practicing structural consultants.

In addition, this book will aid in understanding the platform's structural behavior in terms of its response, service life, and design. The book will serve as a resource regarding the basic structural behavior of complex offshore structures; it will help graduate students understand analysis methodologies and will also help researchers understand the dynamic response of such structures. Readers will learn about new structural geometries of offshore platforms and different methods of analysis for assessing their performance under special loads. The discussion of fatigue analysis and predicting service life will also help professionals during the preliminary and detailed design stages of offshore platforms. This book can serve as reference material for both academicians and offshore practicing professionals.

Both senior undergraduate and post‐graduate students in the disciplines of civil, mechanical, aerospace, structural, offshore, and ocean engineering; applied mechanics; and naval architecture will find this book very useful as a standard classroom reference for analysis and design of special structures. In addition, this book will be useful for practicing engineers and research scholars studying the response behaviors of structures with novel geometry under combinations of extreme loads.

The experimental studies and numerical analyses discussed in the book are the outcomes of research work carried out recently by the authors and research scholars supervised by Srinivasan Chandrasekaran. All discussions, interpretations, and concepts conceived during the detailed research work carried out by the research scholar team are sincerely acknowledged. Administrative support extended by the Centre for Continuing Education (CCE), Indian Institute of Technology, Madras in preparing this manuscript is sincerely acknowledged.

Srinivasan Chandrasekaran
R. Nagavinothini

1.1	Major fixed platforms constructed worldwide (as of 2017).
1.2	Tension leg platforms constructed worldwide.
1.3	Properties of a TMD in the model and prototype (scale 1 : 100).
1.4	Results of free oscillation tests of the TLP model.
1.5	RMS value of surge responses in the presence of random waves.
1.6	RMS value of pitch responses in the presence of random waves.
1.7	Mechanical properties of the Perspex material used for the model.
2.1	Structural details of the BLSRP.
2.2	Natural periods and damping ratios.
2.3	Maximum response of the BLSRP model (0°, 0.1 m).
2.4	Maximum response amplitudes (numerical studies; 6 m wave height).
2.5	Geometric properties of the BLSRP for the stability study.
2.6	Maximum tension amplitude in the tethers in postulated failure cases.
2.7	Mathieu parameters in postulated failure cases.
2.8	Fatigue life (rounded off) of tethers under eccentric loading.
3.1	Characteristics of random sea conditions.
3.2	Comparison of responses to regular waves.
3.3	Deck response to different sea conditions.
3.4	Comparison of deck responses to high sea conditions.
3.5	Tension variation and service life of tethers of buoyant leg 1.
3.6	Characteristics of sea conditions.
3.7	Tether tension variation with combined actions of wind, waves, and current.
4.1	Mechanical properties of marine DH36 steel.
4.2	Ice sea conditions.
4.3	Deck response to different sea conditions.
4.4	Deck response to open water and ice‐covered load cases.
4.5	Collision speed and impact duration.
4.6	Mechanical properties of DH36 steel at a 0.001/s strain rate.
5.1	Properties of the triceratops‐based wind turbine.
5.2	Variation in RAO with changes in the wave heading angle.
5.3	Service life estimation of the triceratops.
5.4	Geometric parameters of the offshore triceratops.
5.5	Mass properties of the triceratops.
5.6	Response of the triceratops given rough sea conditions.