Floating_Structures，_A_Guide_for__Design_and_Analysis.pdf

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1、4Staticsandstability4.1SummaryThischapterdealswiththestaticandstabilityaspectsoffloatingstructures,i.e.ships,semi-submersibles,TLPsandSparbuoys.Afterabasicdiscussionanddefmitionsofthemainparameters,thesimplifiedlinearapproachtostabilityisoutlinedinSection4.3.Thisapproach,basedonstiffhessinroll

2、andpitchforsmallangles,isquitesuitableforfonnulatingmanyaspectsofthestabilityofintactfloatingstructuresbutinanyfmalassessmentitisalsonecessarytopayattentiontononlinearstabilityparametersandtotaketheoverturninganddynamiceffectofwindintoaccountDamagestabilityisimportantforallfloatingstructuresan

3、dusuallyrequiresconsiderationsoflargeanglesandnonlineareffects.Sections4.4to4.11discussmanydetailedaspectsoflinearandnon-linearstabilityanalysis.Designaspectsarehighlighted,foreachtypeofstructurementionedabove,inSection4.12.Sections4.13to4.14discussthecalculationofhydrostaticstiffhesswhichisan

4、importantinputtohydrodynamicmotionanalysisandsometimestostructuralanalysis.Damagestabilitymustbeaddressed,notonlyfromananalyticalpointofviewbutalsotosatisfyrulerequirementswhichreflectthemanypracticallessonsgainedfromoperationalexperience.Therearealsorequirementsforincliningteststodetenninethe

5、actualpositionofthecentreofgravity.ThevariousrulerequirementsandtheirinfluenceondesignisdiscussedinSections4.15to4.20.Section4.21reviewslimitationsandpossiblefuturedevelopments.4.2IntroductionAfloatingvesselmustbedesignedtobeasafeworkingplatfonnwhileundertheinfluenceofthefullrangeofenvironment

6、alconditionswhichitmaybeexpectedtoencounterduringitslife.'Stability'isameasureofthevessel'scapacitytoresistoverturningmomentsandwithstandtheenvironmentalforcesofwind,currentandwaves.Tnaddition,itmustpossesssufficientreservestabilitythatitsoperationisnotoverlyrestrictedandliftingofweightsbycran

7、esorpumpingoffluidscantakeplaceasrequired.Inpractice,awiderangeofenvironmentalconditionswillbeencountered.Nonnaloperationscanbecontinuedsafelyinmostconditionsbuttheremaybeother,moreextremecaseswherenonnaloperationswillceaseandthevesselw