1、 GUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS MARCH 2011 Guide to Color Coding Used in Online Version of the Guide The following summarizes the colors corresponding to Rule Changes, Corrigenda items and editorial changes in the Guide files which are available for download. Rule Chang
2、es: NOTICE NO. 1 July 2013 (effective 1 July 2013) NOTICE NO. 2 October 2015 (effective 1 October 2015) Corrigenda: CORRIGENDA/EDITORIALS 6 March 2012 Editorials: Editorial Changes Guide for Slamming Loads and Strength Assessment for Vessels GUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSE
3、LS MARCH 2011 (Updated October 2015 see next page) American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2011 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA Updates October 2015 consolidation includes: July 2013 ver
4、sion plus Notice No. 2 July 2013 consolidation includes: March 2012 version plus Notice No. 1 March 2012 consolidation includes: March 2011 version plus Corrigenda/Editorials Foreword Foreword This Guide describes the requirements for direct slamming strength assessment for vessels. Optional notatio
5、ns may be assigned to vessels that comply with the requirements in the Guide. The slamming strength requirements in this Guide are supplementary to those in the ABS Rules for Building and Classing Steel Vessels (Steel Vessel Rules, or the Rules) and other Guides published by ABS for classification o
6、f vessels with regard to slamming strength in the hull structure. The Guide contains a description of the direct slamming strength assessment procedure for bottom slamming, bowflare slamming, and stern slamming. The procedure consists of slamming load prediction and strength assessment. The effectiv
7、e date of this Guide is the first day of the month of publication. ABS welcomes comments and suggestions for improvement of this Guide. Comments or suggestions can be sent electronically to rsdeagle.org. ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 iii Table of Contents GUID
8、E FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS CONTENTS SECTION 1 Introduction 1 1 General . 1 3 Slamming Phenomenon 1 5 Application of Guide 2 7 Slamming Strength Assessment Procedure . 2 9 Optional Class Notations 4 11 Nomenclature 4 TABLE 1 Optional Class Notations 4 FIGURE 1 Slamming S
9、trength Assessment Procedure . 3 SECTION 2 Loading Conditions, Speeds, and Headings 8 1 General . 8 3 Critical Loading Conditions for Slamming Load Prediction . 8 3.1 Bottom Slamming 8 3.3 Bowflare Slamming 8 3.5 Stern Slamming . 8 5 Standard Speed Profile . 9 7 Wave Heading 9 TABLE 1 Standard Speed
10、 Profile for Slamming Load Prediction 9 SECTION 3 Extent of Hull Structure to be Evaluated 10 1 General . 10 3 Bottom Slamming 10 5 Bowflare Slamming . 10 7 Stern Slamming 10 FIGURE 1 Extent of Hull Structure for Slamming Load Prediction . 10 FIGURE 2 Typical Frame Stations and Panel Locations for B
11、owflare and Stern Slamming Load Prediction . 11 iv ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 SECTION 4 Wave Environments . 12 1 Wave Scatter Diagram 12 3 Wave Spectrum 12 TABLE 1 IACS Recommendation 34 Wave Scatter Diagram for North Atlantic . 12 SECTION 5 Vessel Motions
12、. 14 1 General . 14 3 Response Amplitude Operator . 14 3.1 Seakeeping Model Development . 14 3.3 Roll Damping . 14 FIGURE 1 Panel Arrangement for Seakeeping Analysis . 15 SECTION 6 Motion Statistics 16 1 General . 16 3 Short-Term Approach . 16 3.1 Sea States . 16 3.3 Spectral Moment of Response 17 3
13、.5 Short Term Extreme Values 18 3.7 Lifetime Maximum Extreme Values . 19 5 Long-Term Approach 19 TABLE 1 Sea States Derived from IACS Rec. 34 Wave Scatter Diagram . 17 FIGURE 1 1-, 25-, 40-Year Return Sea States from IACS Recommendation 34 Wave Scatter Diagram . 16 SECTION 7 Slamming Pressure 20 1 G
14、eneral . 20 3 2D Slamming Approach 20 3.1 General 20 3.3 Slamming Pressure Coefficient . 20 3.5 Three-dimensional Effects . 21 3.7 Dynamic Effects 21 3.9 Design Slamming Pressure . 23 5 3D Slamming Approach 23 FIGURE 1 Typical Pressure Time History in Bowflare Slamming 22 FIGURE 2 Typical Pressure T
15、ime History in Stern and Bottom Slamming 23 ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 v SECTION 8 Direct Strength Assessment . 24 1 General . 24 1.1 Corrosion Margins . 24 1.3 Simultaneous Load Factors . 24 3 Shell Plating 25 3.1 Bowflare Slamming 25 3.3 Bottom and Stern
16、Slamming 25 5 Shell Longitudinals and Stiffeners 26 5.1 Bowflare Slamming 26 5.3 Bottom and Stern Slamming 26 7 Slot Connections . 28 9 Main Supporting Members 32 9.1 Structural Modeling 32 9.3 Boundary Constraints 32 9.5 Slamming Pressure on FE Model 33 9.7 Acceptance Criteria Yielding . 33 9.9 Acc
17、eptance Criteria Buckling 35 TABLE 1 Nominal Design Corrosion Values for Direct Strength Assessment . 24 TABLE 2 Simultaneous Load Factors for Finite Element Analysis of Main Supporting Members 24 TABLE 3 Allowable Stresses for Various Finite Element Mesh Sizes . 34 TABLE 4 Buckling Coefficient Ki36
18、 FIGURE 1 Stiffener Geometry 28 FIGURE 2 Cut-outs (Slots) For Longitudinal 31 FIGURE 3 Boundary Constraints for Forebody Finite Element Model . 33 FIGURE 4 Forebody Slamming Pressure Mapped on Finite Element Model 34 FIGURE 5 Aftbody Slamming Pressure Mapped on Finite Element Model 34 APPENDIX 1 Doc
19、umentation of Strength Assessment for Classification Review . 38 vi ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 Section 1: Introduction SECTION 1 Introduction 1 General This Guide describes a slamming strength assessment procedure for vessels. Typically, there are three typ
20、es of slamming loads on commercial vessels: bottom slamming, bowflare slamming, and stern slamming depending upon the hull geometry at the bow and stern. Upon verifying compliance with the requirements in this Guide, optional notations may be assigned to a vessel. A fundamental requirement of this G
21、uide is that the scantlings of the hull structure are to be in accordance with the criteria as specified in the ABS Rules for Building and Classing Steel Vessels (Steel Vessel Rules). The results of this Guide are not to be used to reduce the basic scantlings obtained from the application of the Ste
22、el Vessel Rules. That is, if the results from this Guide indicate the need to increase any basic scantlings, the increased scantlings are to be implemented above the rule requirements. If software other than that provided by ABS is used, the analysis results for a benchmark case specified by ABS are
23、 to be submitted to demonstrate that the software is compatible with the procedure described in this Guide. 3 Slamming Phenomenon In rough seas, the vessels bow and stern may occasionally emerge from a wave and re-enter the wave with a heavy impact or slam as the hull structure comes in contact with
24、 the water. A vessel with such excessive motions is subject to very rapidly developed hydrodynamic loads. The vessel experiences impulse loads with high-pressure peaks during the impact between the vessels hull and water. Of interest are the impact loads such as bowflare slamming, bottom slamming, s
25、tern slamming, green water and bow impact loads. These impact loads are of a transient nature and can cause severe structural damages. Although the loads are widely varying in their characteristics magnitude, rise time, duration, etc. all involve the impact at high relative velocity between the free
26、 surface of nearly incompressible seawater and the hull structure. The transient impact loads can be highly non-linear and may be strongly affected by the dynamic response of the hull structure. Thus, magnitudes of impact loads/pressures are important for structural design purposes. The following it
27、ems are considered for the determination of the impact pressures: Intensity and duration of impact pressures Spatial distribution and time duration of impact pressures Equivalent static slamming pressures for direct strength assessment and scantling determination Bow and stern geometry For vessels p
28、ossessing significant bowflare, an impact occurs on the side plating of the bow as it is rapidly immersed into the water. This action results in a large fluid pressure covering a comparatively large impact area. There are two types of bowflare impact pressures: non-impulsive pressure and impulsive p
29、ressure. The magnitude of the non-impulsive type pressure is directly related to the bow submergence while the magnitude of the impulsive type pressure rises rapidly at contact and decays exponentially in time. ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 1 Section 1 Introdu
30、ction High slamming pressure can be experienced on stern and bottom hull structures as a vessel emerges and re-enters the water. In this Guide, bottom slamming is considered to occur in the bottom structure in the region of the flat bottom forward of 0.25L (L is the Rule length, as defined in the St
31、eel Vessel Rules) measured from the forward perpendicular (FP). Due to the stern and bottom slamming, two noticeable effects may occur. First, there may be localized structural effects in the areas of the stern and bottom that experience large slamming pressure. This may result in set-up plating and
32、 buckled internal frames, floors and bulkheads. The second effect of the slamming is the vibratory response of the entire hull, or so called whipping, which is not within the scope of this Guide. 5 Application of Guide This Guide can be applied to ocean-going vessels including oil carriers, bulk car
33、riers, container carriers, and gas carriers. The basic principles and requirements in the Steel Vessel Rules are to be reflected in the hull structure. The following slamming loads are covered in this Guide: Bottom slamming for all vessel types when the heavy weather ballast draft forward is less th
34、an 0.04L Bowflare slamming for container carriers, liquefied gas carriers, or other vessels possessing significant bowflare Stern slamming for vessels such as container carriers with significant overhanging sterns or liquefied gas carriers with relatively flat stern cross sections For vessels with t
35、he stern and/or stern geometry features that deviate significantly from the conventional arrangements, the scope of direct strength assessment against slamming loads is to be determined in consultation with ABS. The design slamming pressures on the bottom, bowflare, and stern are defined as the most
36、 probable extreme loads on those areas during the 25 years of service life in the North Atlantic. A direct slamming strength assessment under this unrestricted service condition is required. This Guide provides a rational, step-by-step, direct calculation method for the slamming strength assessment
37、of the bottom, bowflare and stern structures. Section 2 provides recommendations for the loading conditions, speeds, and headings. The locations to be analyzed are explained in Section 3. Environmental conditions are described in Section 4, which is followed by the calculation of vessel motions in S
38、ection 5. Statistics of motion is explained in Section 6. The calculation of design slamming pressure is explained in Section 7. Then, the strength assessment is covered in Section 8. 7 Slamming Strength Assessment Procedure Section 1, Figure 1 shows a flow chart describing the slamming strength ass
39、essment procedure. 2 ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 Section 1 Introduction FIGURE 1 Slamming Strength Assessment Procedure (For Each Loading Condition) Select Loading ConditionsSection 2Determine Location and Extent ofSlamming Affected RegionSection 3Obtain Env
40、ironmental DataSection 4Perform Analysis of Vessel MotionSection 5Calculate Design Slamming PressureSection 7Statistical Analysis for Relative VerticalVelocity and Relative Vertical MotionSection 6Strength Assessment forShell Plating and StiffenersSection 8Strength Assessment forOpenings (Cutouts)Se
41、ction 8Strength Assessment forMain Supporting MembersSection 8Calculate RAOs for Relative VerticalVelocity and Relative Vertical MotionObtain Scantlings and CalculateStructural PropertiesSlammingLoadPredictionStrengthAssessmentABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 3 S
42、ection 1 Introduction 9 Optional Class Notations In recognition of full compliance with the strength criteria in Section 8, optional class notations may be granted. A summary of requirements and a brief description is given in Section 1, Table 1. TABLE 1 Optional Class Notations Notation Description
43、 Requirements SLAM-B Strengthened against Bottom and/or Bowflare slamming The vessel needs to satisfy the ABS bottom slamming and/or bowflare slamming procedure and criteria in the bow area, depending on vessel type and hull form SLAM-S Strengthened against Stern slamming The vessel needs to satisfy
44、 the ABS stern slamming procedure and criteria in the stern area 11 Nomenclature The following symbols are used in this Guide. For some symbols, additional details are given where the symbols are used in this Guide. Also, some symbols, such as symbols for constants, are not listed in this section. R
45、efer to the description with each formula for those not listed. Ac= effective shear sectional area of the support or of both supports for double-sided support, (= Alc+ Ald), in cm2(in2) Alc= shear connection area of lug plate (= f1ctc), in cm2(in2) Ald= shear connection area excluding lug plate (= d
46、ttw), in cm2(in2) As= attached area of the flat bar stiffener, in cm2(in2) As= cross-sectional area of the spring rod, in cm2(in2) Ashear= effective shear area of a hull girder cross section, in cm2(in2) AP = After Perpendicular B = breadth of vessel, in m (ft) C3D= three-dimensional correction fact
47、or (= 0.83CL) for slamming pressure Ca= permissible bending stress coefficient Cd= plate capacity correction coefficient (= 1.0) CL=location factor for bottom slamming pressure near FP Cp= local pressure coefficient Cs= dynamic load factor, as described in 7/3.7 di= vertical distance from the still
48、water surface to the location, in m (ft), if the location is above the water surface, then it becomes zero. dm= mean draft of vessel, in m (ft) E = modulus of elasticity of the material, may be taken as 2.06 107N/cm2(2.1 106kgf/cm2, 30 106lbf/in2) for steel f = spreading function for short-crested w
49、aves, as defined in Subsection 4/3 4 ABSGUIDE FOR SLAMMING LOADS AND STRENGTH ASSESSMENT FOR VESSELS .2011 Section 1 Introduction f1= shear stiffness coefficient in slot connection check, or an adjusted yield point of material in shell plating check f2= an adjusted yield point of material in shell plating check fb= calculated ideal bending stresses in buckling check, in N/cm2(kgf/cm2, lbf/in2) fb= an adjusted yield point of material in stiffener check fbdg= bending moment factor in stiffener check fc= collar load factor for slot connection chec
