ABS 225-2016 GUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS.pdf
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1、 Guidance Notes on Structural Analysis of Self-Elevating Units GUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS APRIL 2016 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2016 American Bureau of Shipping ABS Plaza 16855 Northchase D
2、rive Houston, TX 77060 USA ii ABSGUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS .2016 Foreword Foreword The guidance contained herein should be used in conjunction with the ABS Rules for Building and Classing Mobile Offshore Drilling Units for the purpose of ABS Classification of a Se
3、lf-Elevating Unit. The guidance indicates acceptable practice in a typical case for types of designs that have been used successfully over many years of service. The guidance may need to be modified to meet the needs of a particular case, especially when a novel design or application is being assess
4、ed. The guidance should not be considered mandatory, and in no case is this guidance to be considered a substitute for the professional judgment of the designer or analyst. In case of any doubt about the application of this guidance ABS should be consulted. A self-elevating unit is referred to herei
5、n as an “SEU”, and the ABS Rules for Building and Classing Mobile Offshore Drilling Units, are referred to as the “MODU Rules”. These Guidance Notes become effective on the first day of the month of publication. Users are advised to check periodically on the ABS website www.eagle.org to verify that
6、this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be sent electronically by email to 0Hrsdeagle.org. Terms of Use The information presented herein is intended solely to assist the reader in the methodologies and/or techniques discussed. T
7、hese Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the responsibility of the reader to perform their own assessment and obtain professional advice. Information contained herein is considered to be pertinent at the time of publication, but may
8、be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information and the reader assumes full responsibility for compliance. This publication may not be copied or redistributed in part or in whole without prior written consent from ABS. Table of
9、Contents GUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS CONTENTS SECTION 1 Introduction 1 1 Overview . 1 3 General Requirements of Strength Analysis . 1 5 Information Required for Strength Analysis 1 5.1 Units Data . 1 5.3 Gravity and Functional Load 2 5.5 Environmental Data . 2 7 Met
10、hods of Analysis 8 7.1 Static Response 8 7.3 Dynamic Response . 8 TABLE 1 Wind Pressure Height Coefficients . 3 FIGURE 1 Plot of Wind Force Height Coefficient vs. Height above Design Water Surface . 4 FIGURE 2 Current Velocity Profile . 7 FIGURE 3 Water Depth 7 SECTION 2 Loads . 9 1 Overview . 9 3 G
11、ravity and Functional Loads . 9 5 Wind Load . 10 5.1 Wind Load on Open Truss . 10 5.3 Wind Load on Leg . 11 5.5 Dynamic Effects and Vortex Induced Vibration . 11 7 Wave and Current Loads 11 7.1 Validity and Application of the Morisons Equation 11 7.3 Hydrodynamic Coefficients 12 7.5 Wave Theories 19
12、 7.7 Asymmetry 20 7.9 Stretching 20 7.11 Shielding 21 7.13 Wave Approach Angle . 21 7.15 Breaking Wave and Slamming 21 7.17 Stepping Wave through Structures 22 ABSGUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS .2016 iii 9 Large Displacement Load (P- Effect) 22 9.1 Large Displacement M
13、ethod 22 9.3 Geometric Stiffness Method 22 11 Dynamic Load (Inertial Effect). 24 11.1 Magnitude of Inertial Load . 24 11.3 Distribution of Inertial Load 24 13 Leg Inclination . 24 TABLE 1 P- Effect Approaches 23 FIGURE 1 Non-cylindrical Chords 13 FIGURE 2A Drag Coefficient of Tubular Chord with Rack
14、: Deterministic Analysis . 14 FIGURE 2B Drag Coefficient of Triangular Chords: Deterministic Analysis . 14 FIGURE 3 One Bay of Lattice Leg . 17 FIGURE 4 Split-Tube Chord Section 17 FIGURE 5 Triangular Chord Section 18 FIGURE 6 Wave Theories Applicability Regions (After API RP2A) . 19 FIGURE 7 Wheele
15、r Stretching of Wave . 21 SECTION 3 Structural Analysis Models . 25 1 Overview . 25 3 Structural Model 25 3.1 Hierarchy of Models . 25 3.3 Hull Model 27 3.5 Leg Model 28 3.7 Leg-to-Hull Connection Model . 30 3.9 Foundation Modeling . 36 TABLE 1 Applicability of Leg Models . 25 TABLE 2 Applicability
16、of Hull Models . 25 TABLE 3 Applicability of Connection Models . 26 TABLE 4 Comparisons of Global Models . 26 FIGURE 1 Simplified Guide Modeling 33 FIGURE 2 Linearization of Guides . 35 FIGURE 3 Eccentricity of Spudcan 37 SECTION 4 Structural Analyses 38 1 Overview . 38 1.1 Two-Step Procedure Analys
17、is . 38 1.3 Step 1 Dynamic Analysis and Inertial Load Set 38 1.5 Step 2 Quasi-static Analysis . 39 1.7 Critical Storm Load Directions . 40 1.9 Exception . 40 iv ABSGUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVATING UNITS .2016 3 Specification of Wave Parameters and Spudcan-Soil Stiffness . 41 3
18、.1 Introduction 41 3.3 Spectral Characterization of Wave Data for Dynamic Analysis . 42 3.5 Spudcan-Soil Rotational Stiffness (SC-S RS) . 42 5 Dynamic Analysis Modeling 43 5.1 Introduction 43 5.3 Stiffness Modeling . 43 5.5 Modeling the Mass 45 5.7 Hydrodynamic Loading 45 5.9 Damping 45 7 Dynamic Re
19、sponse Analysis Methods . 46 7.1 General 46 7.3 Random Wave Dynamic Analysis in Time Domain . 46 7.5 Other Dynamic Analysis Methods . 53 9 Dynamic Amplification Factor and Inertial Load Set . 55 9.1 Introduction 55 9.3 Inertial Load Set based on Random Wave Dynamic Analysis . 55 9.5 Inertial Load Se
20、t based on SDOF Approach . 56 9.7 Inertial Load Set Applications 56 FIGURE 1 Flowchart of Two-step Procedure . 41 FIGURE 2 The Drag-Inertia Method Including DAF Scaling Factor . 50 FIGURE 3 Graphical Representation of DAF Scaling Factor, FDAF, Applied in the Drag-Inertia Method . 51 SECTION 5 Commen
21、tary on Acceptance Criteria . 57 1 Introduction . 57 3 Categories of Criteria 57 5 Wave Crest Clearance and Air Gap . 57 7 Overturning Stability 57 9 Structural Strength 58 9.1 Yield Criteria 58 9.3 Buckling Criteria 59 9.5 Hybrid Members 59 9.7 Punching Shear . 60 9.9 P- Effect on Member Checking 6
22、0 11 Fatigue of Structural Details 60 13 Strength of the Elevating Machinery . 60 15 Spudcan Check . 61 15.1 Preload Condition 61 15.3 Normal Operating and Severe Storm Conditions 61 17 Other Checks 61 FIGURE 1 Chords Section Stress Points . 60 ABSGUIDANCE NOTES ON STRUCTURAL ANALYSIS OF SELF-ELEVAT
23、ING UNITS .2016 v APPENDIX 1 Equivalent Section Stiffness Properties of a Lattice Leg . 62 1 Introduction . 62 3 Formula Approach 62 3.1 Equivalent Shear Area of 2D Lattice Structures 62 3.3 Equivalent Section Stiffness Properties of 3D Lattice Legs . 63 TABLE 1 Equivalent Shear Area of 2D Lattice S
24、tructures . 64 TABLE 2 Equivalent Moment of Inertia Properties of 3D Lattice Legs 65 FIGURE 1 Shear Force System for X Bracing and its Equivalent Beam . 62 APPENDIX 2 Equivalent Leg-to-Hull Connection Stiffness Properties 66 1 Introduction . 66 3 Empirical Formula Approach . 66 3.1 Horizontal Stiffn
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