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,) ELSEVIER MARINE STRUCTURAL DESIGN Elsevier Internet Homepage: http:Nwww.elsevier.com Consult the Elsevier homepage for full catalogue information on all books, journals and electronic products and services. 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Should you have a publishing proposal you wish to discuss, please contact, without obligation, the publisher responsible for Elsevier's civil and strucutral engineering publishing programme: James Sullivan Publishing Editor Elsevier Ltd The Boulevard, Langford Lane Kidlington, Oxford OX5 IGB, UK Phone: -4-44 1865 843 178 Fax: +44 I865 843920 E.mail: j.sullivan@elsevier.com General enquiries, including placing orders, should be directed to Elsevier's Regional Sales Offices - please access the Elsevier homepage for full contact details (homepage details at the top of this page). MARINE STRUCTURAL DESIGN YONG BAI 2003 ELSEVIER Amsterdam - Boston - Heidelberg - London - New York - Oxford Paris - San Diego - San Francisco - Singapore - Sydney - Tokyo ELSEVIER SClENCE Ltd The Boulevard, Langford Lane Kidlington, Oxford OX5 IGB, UK 8 2003 Dr. Yong Bai. All rights reserved This work is protected under copyright of Dr. Yong Bai with assigned rights to Elsevier Science. 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British Library Cataloguing in Publication Data Bai, Yong Marine Structural Design 1. Offshore structures - Design and construction 2. Marine engineering 1. Title 627.9’8 ISBN: 0-08-043921-7 8 The paper used in this publication meets the requirements of ANSVNISO 239.48-1992 (Permanence of Paper). Printed in Hungary. 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 [...]... factored down Use of Load and Resistance Factores for Strength Design Strength and Fatigue Analysis Major factors that should be considered in marine structural design include: Still-water and wave loads, and their possible combinations Ultimate strength of structural components and systems Fatigue/ fracture in critical structural details Knowledge of hydrodynamics, bucklinglcollapse, and fatiguehacture is... to ship and offshore structures The objective of this book is to summarize the latest developments of design codes, engineering practice and research into the form of a book, focusing on applications of finite element analysis and riskheliability methods The calculation of wave loads and load combinations is the first step in marine structural design For structural design and analysis, a structural. .. optimize structural design The design by analysis approach is now applied throughout the design process The finite element analysis has been very popular for strength and fatigue analysis of marine structures In the structural design process, the dimensions and sizing of the structure are Part I Struchlral Design Principles 4 strengthened, and structural analysis re-conducted until the strength and fatigue. .. 20.4 Structural Analysis 379 20.4.1 Overall Structural Analysis 379 381 20.4.2 Local Structural Analysis 20.5 Fatigue Analysis and Design 381 20.5.1 Overall Design 381 382 20.5.2 Stress Range Analysis 20.5.3 Spectral Fatigue Parameters 382 20.5.4 Fatigue Damage Assessment 387 20.5.5 Fatigue Analysis and. .. during a cyclic loading The values of material properties C and m may be found fiom design codes for typical materials used in marine structures and other types of steel structures The stress intensity factors may be available fiom handbooks for simplified structural and defect geometry's and loads 1.3 1.3.1 Structural Reliability Applications Structural Reliability Concepts Component reliability concerns... environmental, material consequences and the loss of human life Extreme and accidental loads differ in the sense that the magnitude and frequency of the extreme loads can be influenced to a small extent by the structural design, whereas active controls may influence both the frequency and the magnitude of accidental loads The design for accidental loads includes determination of design loads based on risk consideration,... simulate the structural behavior in accidental scenarios and to design the structure for the performance standards Use of the finite element analysis enables us to deal with complex accidental scenarios and to better predict the structural response Design for Fatigue 1.2.3 Fatigue damage and defects may threaten integrity of the marine structures This concern is aggravated as the cost of repair and loss... bucklinglcollapse, and fatiguehacture is the key to understanding structural engineering Part I Siruciural Design PrincipIes 6 1.2.1 Ultimate strength Criteria Ultimate strength criteria are usually advocated in design codes for various basic types of the structural components such as: columns & beam-columns plates and stiffened panels shells and stiffened shells structural connections hull girders An illustration... the LRFD approach is its simplicity (in comparison with direct use of the structural reliability methods) while it accounts for the uncertainties in loads and structural capacities based on structural reliability methods The LRFD is also called partial safety factor design While the partial safety factors are calibrated using the structural reliability methods, the failure consequence may also be accounted... formulae and charts in classification rules and design codes The basic scantling of the structural components is initially determined based on stress analysis of beams, plates and shells under hydrostatic pressure, bending and concentrated loads Three levels of marine structural design have been developed: Level 1: Design by rules Level 2: Design by analysis Level 3: Design based on performance standards . LV iARINE U TRUCTURAL DESIGN Ultimate strength, Structural reliability, Fatigue and frature Risk assessment Loads Functional requirements I I I I Limit-state. Overall Structural Analysis 379 20.4.2 Local Structural Analysis 381 20.3 Time-Domain Fatigue Assessment 377 20.3.1 Application 377 20.4 Structural Analysis 379 20.5 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