船舶结构设计准则和衡准的研究进展.pdf

Research Progress of Design Principles andCriteria of Ship StructuresZHAN Zhi-hu1,3,WU Wen-wei2(1.Shanghai Rules&Research Institute of China Classification Society,Shanghai 200135,China;2.China Ship Scientific Research Center,Wuxi 214082,China;3.Ships and Offshore InstallationsStructural Safety Laboratory,Shanghai 200135,China)Abstract:This paper presents a review of the research progresses in the design principles and criteriaof ships and offshore structures achieved in IACS,IMO and ISO/TC8 in the past several years,withconsideration of the development of new rules and guidelines of IACS members and structural safetyregulations of regional maritime authorities.The influences of digital twin,operation data,reliability,risk assessment,and human factors in the design on the structural design criteria are discussed.Eventually the suggestions on the development direction of future maritime regulations are given.Key words:design principle;design criterion;reliability;risk assessment;human factorCLC number:U661.4Document code:Adoi:10.3969/j.issn.1007-7294.2023.06.0130 IntroductionThe principles and criteria of ship structural design involve the relevant scientific principles,engineering application methods and engineering application scenarios in the whole life cycle ofhull structure design,construction and operation,and have always attracted the attention from themaritime industry.The International Ship&Offshore Structures Congress has specially set up acommittee(ISSC IV.1)to follow up this subject.International Maritime Organization(IMO),International Association of Classification Societies(IACS)and the International Organization for Standardization(ISO)have always had relevant issues and project studies.This paper summarizes the development of rules and regulations on maritime structure sincethe release of ISSC 2018 committee report,mainly focusing on the progresses made by InternationalAssociation of Classification Societies(IACS),International Maritime Organization(IMO),International Organization for Standardization(ISO)and major classification societies of IACS,and covering some current hot topics.1 Latest development in rules and standards1.1 Development of IACS relevant work in design principleStructural rules for ships and offshore installations are developing with the trend of applying第27卷第6期船舶力学Vol.27 No.62023年6月Journal of Ship MechanicsJun.2023Article ID：1007-7294（2023）06-0947-12Received date:2022-12-25Foundation item:Supported by the Project of Ministry of Industry and Information Technology（CB05N20）Biography:ZHAN Zhi-hu(1970-),male,Ph.D.,corresponding author,E-mail:;WU Wen-wei(1969-),male,professor.goal and risk based methods.Common Structural Rules(CSR for BC&OT)was developed by IACSbased on the IMO GBS requirement，and updatedversions1are published annually by the continuous work of CSR maintenance team.In addition,several project teams2-5have been established tofocus on hull structural safety issues,includingwhipping on container ships,wave data investigations,etc.Main project teams in IACS Hull Panelare listed in Tab.1.Although the above research results haven t been published now,they will have a significantimpact on marine industry after they have become the unified requirements or recommendations ofIACS.For example,based on the current PH40 investigations(comparison with directly calculatedresults based on current Rec.34),it can be concluded that for smaller ships the results for the bending moment will on average be in line with the current rule requirements,for larger ships they mightbe higher.This will have an effect on ship structure design criteria.1.2 Development of IMO relevant work in design principleSince 2017,the Maritime Safety Committee(MSC)of IMO has held five sessions6-10,the maintopics of which concern design criteria,including autonomous ships,goal-based new ship construction standards,goal-based standards safety level approach,polar operation manual,formal safetyassessment,ship design and construction etc.IMO takes the first step to address regulatory scopingexercise(RSE)on Maritime Autonomous Surface Ships(MASS),GBS Verification Guideline Revisions,including goal-based Safety Level Approach(SLA),interim guidelines agreed in principleduring MSC 99.During MSC 100,four degrees of autonomy of unmanned MASS in RSE were approved to take into force,and interim guidelines for development and application of the IMO goal-based standards safety level approach was also approved by the Committee11.During MSC 101,therevised generic guidelines for developing IMO goal based standards was approved by the Committee12,the guidance for navigation and communication equipment intended for use on ships operating in polar waters was approved by the Committee,revised guidelines on alternative design and arrangements for SOLAS Chapters II-1 and III and new safe mooring requirements were also adoptedduring MSC 102.The MSC completed RSE for the use of MASS and approved a circular providingthe outcome13.Detecting and reporting containers lost at sea is a new topic during MSC 103.It can be seen from the above that the use of risk assessment methods to formulate IMO ruleshas been throughout the development of GBS guidelines,in which IMO SLA and FSA are being improved as prerequisites for risk-based GBS.1.3 ISO/TC8 status on maritime design standards14ISO/TC8 aims at ships and marine technology standardization of design,construction,training,structural elements,etc.Since 2018,ISO TC8 has established some new working groups and disbanded some working groups.Standard development mainly involves in marine evacuation system,life saving and fire protection,servicing of inflatable life-saving appliances,pilot ladders,launching appliances for fast rescue boats,revising standards on mooring systems,etc.The above-menPT No.PH38PH40PH43PH44PH45TaskWhipping on container shipsWave data investigationsBuckling requirementsFatigue assessmentCSR corrosion additions reassessmentTab.1 Project teams in IACS Hull Panel5948船舶力学第27卷第6期tioned standards are derived from the SOLAS convention,LAS codes and FSS codes.ISO calls onIMO member states and international organizations to participate in the preparation and revision ofISO ship and marine technical standards through national ISO branches so as to promote the effective implementation of IMO instruments.In short,there is no new progress in the design criteria andmethods of ships and offshore installations,but the proposals of many standards on mooring requirecareful alignment between ISO and IMO15.2 Latest development in classification s rulesClassification societies update their rules every year.No matter how different the standards ofstructural strength and the principles behind it are,the concept of the rules of each classification society is the same,i.e.minimum scantling requirement using prescriptive rules calculation combinedwith direct calculation analysis notation,e.g.,ABS using DLA16,BV using VeriStar Hull17，CCS using Compass(D)18,DNV using NAUTICUS19,LR using Ship Right(D)20,it can be seen that directanalysis has been a popular approach in classification rules.The existing classification rules do not clearly state fundamental principles on which they arebased,it is often not possible to relate all aspects of the structural requirements explicitly to theload and capacity models that are used in most modern structural design codes.The CSR OT and CSR BC have gradually been widely recognized by the marine sector sincetheir entry into force,for the emphasis of the rule was on greater transparency,they also meet theneed for increased robustness in ship design and construction.With the successful application ofcommon structure rule,major classification societies have begun to upgrade or develop goal-basedstructural rules.The main feature of the rules is the load transparency.The dynamic loads covernormal service loads and more extreme hull girder loads for ultimate strength in the intact condition.A net thickness philosophy has been adopted,i.e.the strength calculations performed duringthe design stage are based on net scantlings principle.After the merger of DNV and GL in 2012,there was an inconsistency between the two rule systems.In order to unify the rule requirements,DNVGL started to develop new rules after the merger,and released a new structural rule in 2015.One of the most significant advances in the new rules isthe introduction of Equivalent Design Waves(EDW)to calculate environmental loads.EDW enables a more accurate representation of these loads and consequently a more precise stress description of a vessel s structure.This set of structural rule is applicable to most ship types19.Unlike the DNV rule,BV developed a structural rule specifically applicable to container shipsand came into effect on July 1,2016.The rule introduced vertical bending moment and shear forcefrom UR S11A.New formula for horizontal bending moment/shear force,torque,motions/accelerations and pressure were also included in the rule.The structure strength assessments includingyielding,buckling and fatigue are based on net scantling approach and several sets of design wavestogether with loading combination factors for each design wave21.In response to the demand for the large-scale development of container ships,CCS adoptedthe concepts and methods of the IMO Bulk Carrier and Oil Tanker Goal Based Ship Construction第6期ZHAN Zhi-hu et al:Research Progress of Design Principles and 949Standards and developed a new container ship structure rule,which came into effect on July 1,202222.The transparency of the goal-based rules has been widely recognized by the industry.Although so far,only DNV,BV and CCS have issued goal-based structural rules,it is believed thatmore goal-based rules will appear in the near future.3 Special topics3.1 Digital twinThere is no doubt that the digital twin is the future.Being able to predict potential dangers andcreate the optimum design will enhance safety and operation greatly.With the element of the unknown significantly limited,the digital twin concept can help the shipping industry make better useof digitalization,and move to a new era.In 2020,two international standard projects,i.e.ISO/IECAWI 30172 and ISO/IEC AWI 30173,were under development23.The draft standard of ISO 23247-digital twin framework for manufacturing was released24,including four parts:overview and basicprinciple,reference architecture,digital expression of physical manufacturing elements and information exchange.Some standards were also issued in classification society.LR issued the digital health management system approval procedure.The procedure introduces the approval method,approval scopeand data to be submitted of the digital health management system25.DNV issued the recommendation practice A204 Qualification and Assurance of Digital Twins,which puts forward six levels ofdigital twins26.Related to design principles and criteria,an important task is how to express the rules andstandards themselves using digital method.This is an important subject of digital transformation ofship structure.3.2 In-service updating,criteria for re-assessmentClassification societies are well aware of the importance of accumulating operation data of maritime facilities,promoting the research and real ship application of hull monitoring system,formulating relevant technical requirements,and controlling the risk of classified ships by means of additional notation.The relevant additional notations are listed in Tab.2.Tab.2 Additional notation for hull monitoring systemClassification(Acronym)ABS27BV28CCS18DNV19LR29Class notationHM1+R(SW)/(GS),HM2+R(HGS),HM3(VDR)MON-HULLHMS(x)：for conventional ships;HMS-HSC(x)：for high-speed shipsHMON(x)ShipRight(SEA(x)Categorized byMonitoring typeSensor typeSensor typeMonitoring typeIn recent years,with the development of ice breakers and polar routes,classification societieshave put forward corresponding requirements for stress monitoring of ships sailing in ice areas,and950船舶力学第27卷第6期granted additional notations are listed in Tab.3.Some classification societies are establishing hullmanagement systems throughout the whole life cycle.An important task is to combine the hull monitoring data with the digital simulation of the hull structure.Theaccuracy of a digital simulation system is verified bythe hull monitoring data.On this basis,the ship structure design criteria and standards are calibrated.3.3 Polar principlesIMO has issued the International Code for Ships Operating in Polar Waters(Polar Code)32,which entered into force on January 1,2017.In June 2019,IMO successively issued two circulars33-34,Msc.1/circ.161233concerns the general requirements and specific performance standardsfor navigation and communication equipment intended for use on ship operation in polar waters,and Msc.1/circ.161434is a guidance document on compliance with Section 8.3(life saving devicesand arrangements)of Part I-A of the International Code for the Operation of Ships in Polar Waters.IACS issued the UR I Requirements Concerning Polar Class in 2006.The polar classificationrequirements is divided into seven grades PC1-PC7,including structural requirements and machinery requirements of polar ship35-37.Major classification societies have also successively issuedcodes and guidelines related to polar ships.For example,ABS has issued the ice load guide for rotary thruster,the operation guide for ships in low temperature environment and the guide for ice loadmonitoring system.BV has issued the enhanced selection of ice areas in different navigation areasin the world and the current ship operation guide in polar waters38-39.CCS has issued AdditionalRequirements for Ships Operating in Low Air Temperature Environments,Guidelines for PolarShip,the Interim Guidelines for the Inspection of Polar Transport Landing Craft and Guidelinesfor Hull Monitoring and Assistant Decision-Making System for Operation in Ice40-43.DNV issuedice strengthening of propulsion machinery and winterization for cold climate operations,etc.44-45.There are 57 international standards14related to polar ships issued by the International Organization for Standardization,mainly involving technical committees such as ISO TC8,TC17,TC45,TC67,TC98,TC153 and TC220.11 of these standards can be directly applied to polar ships andinstallations,covering such professional fields as arctic operationenvironmental monitoring andprediction in Arctic area,ship material requirements in low temperature environment,polar shipslow temperature environment deck machinery,etc.Nine of these standards are listed in Tab.4.46items are related to polar ships and installations,which can be used as a reference for the design,construction and testing of polar facilities and their related materials and equipment,including low-temperature materials and products,polar offshore structure requirements,ice load determinationand other fields.Tab.4 List of polar international standardsDesignated No.IS