工程管理外文文献.docx
《工程管理外文文献.docx》由会员分享,可在线阅读,更多相关《工程管理外文文献.docx(8页珍藏版)》请在冰豆网上搜索。
![工程管理外文文献.docx](https://file1.bdocx.com/fileroot1/2023-1/30/ffd21f7f-d827-4cde-97ba-2c887238e077/ffd21f7f-d827-4cde-97ba-2c887238e0771.gif)
工程管理外文文献
StudyonTheoryofReliabilityAnalysisinConstructionRiskManagement
DENGTiejun&QIUYike
(CollegeofCivilEngineering,HunanUniversity,Changsha410082,Hunan,China)
Abstract:
Thestateoftheartofreliabilityanalysisforconstructionsystemsisinvestigated.Itispointedoutthatmostofthecurrentresearchinconstructionreliabilityanalysisarelimitedtoasinglespecificgoalormanagementproblem.Startingfromthetheoryofsystemengineering,theconceptofreliabilityforconstructionsystems,whichisdifferentfromthereliabilityofstructuraldesignbutcloselyrelatedtoitisdefined;andtherelationshipbetween“GoalSubsystem”and“ProcedureSubsystem”ispresentedbytakingintoaccountofthefeaturesofconstructionpractice.Analgorithmofthereliabilityanalysisforthe“GoalSubsystem”and“ProcedureSubsystem”isproposed,andtheapproachesforimprovingthesystemreliabilityareexplored.Theclassificationofreliabilitylevelsanditsrelationshipwithconstructionriskmanagementarealsopresented,andthepossibilitiesoffutureapplicationofthereliabilitytheoryinconstructionriskmanagementdiscussed.
Keywords:
reliabilityanalysis;constructionriskmanagement;systemsengineering;theclassificationofreliabilitylevels
1Introduction
Since1916BarChartwasinventedbyH.L.Ganttandappliedintotheflowproduction,flowproductionmethodswasextensivelyadoptedintheorganizationoftheengineeringconstruction.Till2000GabrielA.Barrazaproposed‘S’and‘SS’curvestomodeltheengineeringconstruction.Thatmodelextendedthedeterministiccost-schedulecontrolmethodintoaprobabilisticmodel.Basedontheprobabilisticanalysisforthereliabilityofcost-schedulecontrolusingprobabilitytheoryandmathematicalstatisticaltechniques,thismethodcangivearationalframeworkforthedecisioninengineeringconstruction}}}.Allthisprovesafactthatconstructionreliabilityhaslongbeenstudiedandappliedintheconstructiontechnologyandmanagement.However,thepreviousresearchesstudiedthecontrolandmanagementonlyofasingleobjectiveamongthewholeobjectivesystemforconstruction.Theydidn'tconsidertheuniquecharacteristicsoftheengineeringconstructionasawholesystem;thereforetheyfailtoinstructthepracticalissuesoccurringintherealconstructionprojectmanagementbasedontheirreliabilityanalysis.
Themodernconstructionisanincreasinglycomplicatedprocesssystem.Fromtheviewofsystemengineering,eachprocedureortaskinanengineeringprojectcanonlybeaccomplishedaftermeetingsimultaneouslyseveralobjectivesunderbothexternalandinternalconstraints.Aswaspointedout[2],foranengineeringprojectunderreasonableeconomicconstraint,itsperformancecanbedefinedintermsof
(1)degreeofmeetingthequalitystandards,
(2)assuranceofmeetingthetimedurationrequirement,(3)credibilityofconstructionsafety,and(4)satisfactionofmeetingthesiteenvironmentrequirement.Hence,thereliabilityofaconstructionprojectreferstothefeasibility,possibilityandsafetyofthewholeproductionactivities.Thatis,inordertoguaranteethereliabilityofaconstructionproject,wehavetoassurethefeasibility,possibility,credibilityandsafetyofaprojectunderspecifiedconditions.Generally,however,allthefactorsaffectingtheaccomplishmentoftheprojectarerandomvariables.DenotedbyPt,thereliabilityofconstructioncanbemathematicallymeasuredbytheprobabilityof‘meetingthedesignrequirement’or‘meetingthepre-specifiedprojectperformanceaccordingtotheprojectplanning’.Associatedwiththereliabilityofconstructionisitsprobabilityoffailure,denotedbyPf.Thetwoeventsareexclusive,i.e.,Pt+Pf=1,orPt=1-Pf,where0≤Pt≤1,0≤Pf≤1.Obviously,thereliabilityofconstructioncanalsobedescribedbythenrobabilitvoffailureofaconstructionproject,thatis,wecanjudgethereliabilityofaprojectfromitsprobabilityoffailurebeinglessthantheacceptablerisklevel.Asaresult,itisdesirabletoapplytheprincipleofreliabilityanalysisontotheengineeringriskmanagement,aimingtoimprovetheabilityofriskaversionforanengineeringproject.
Asectionshouldbeprovidedtobrieflyintroducetherestofthepaper.
2ReliabilityAnalysisofConstructionObjectiveSystems
TheperformanceofanengineeringconstructionactivitycanbedefinedintermsofQuality(Q),TimeDuration(T),Safety(S),Normal(N)andCosts(C).Accordinglythereliabilityoftheconstructionactivityshouldbeexpressedasahierarchymulti-objectivesystem,withfirstlayerbeingTimeDuration(T),Safety(S),Normal(N),andsecondlayertheCosts(C).Figure1demonstratestherelationshipamongtheobjectives.
Fig.lRelationmodelforobjectivesystemofconstructionactivity
Asfarasaspecificconstructionprocedureisconcerned,therearesomedifferenttaskstorealizeacertainobjectiveinthefirstobjectivelayer,say,Y}.Therelationshipofthesetaskscanbecategorizedasfollowingcases.
(1)Independence.Eachtaskisindependentfromtheothers,andeachcontributessomehowtotherealizationoftheobjective.However,whenthesetasksapplysimultaneously,thefollowingtaskhelpstherealizationofthecontributionfromtheprevioustask.Forexample,inthecastingofmassconcrete,thefollowingseparatetaskscontributeindependentlytothetemperaturecontrol,whichistheobjectiveoftheconstructionprocedure:
addingtheconcreteadditivetoreducethehydrateheat,coveringtheplasticinordertokeepwarm,embeddingcoolingpipelines,etc.
(2)Logicalcorrelation.Onlyaftertheprevioustaskcanthefollowingtaskbegin.Forexample,therelationbetweenlocalizationofformworksandthemeasure/lininginestablishingtheformworksofreinforcementconcretemembercastinsitu.(3)Thecombinationofthe
(1)and
(2),i.e.,thetasksarebothindependentandlogicallycorrelated.
Hence,forcase
(1),ifdenotebyφij(0≤φij≤1)theeffectivenessoftheit"task。
。
therealizationofobjectiveYi,then
⑴
Wherepti(n)isthereliabilityofobjectivewhenntasksareindependent.
Forcase
(2)whenmtasksareapplied,
pti(m)=min{φik/k=1,2,3,……,m}⑵
wherepti(m)isthereliabilityofobjectivewhenmtasksarelogicallycorrelated.
Forcase(3),thetargetreliabilitycanbecalculatedfromequation
(1)and
(2).
SupposethecostsoftheithtaskareCijforcase
(1)andCikforcase
(2),respectively.Thenforcase(3)whichisthecombinationofcase
(1)andcase
(2),thetotalcostforrealizingtheobjectiveY}inthefirstlayeris
⑶
Forcase
(1),aftertheprevious(n-1)tasks,theadditiveeffectivenessfromthenthtask,whichcanimprovethereliabilityoftheobjectiverealization,canbederivedfromequation
(1):
⑷
wherePfi(n-1),Pfi(n1)areprobabilitiesoffailureafter(n-1)andntasks,respectively.
Therefore,forcase
(1),weshouldchoosethemosteffectivetaskamongthealternativesbasedonthereliabilityofobjectwhichhasalreadypossessesaftertheprevioustasks.Insodoing,thefollowingtaskscanbereduced,andthecostsdeductedaccordingly.Forcase
(2),however,weshouldguaranteethequalityofeachtask.Itisnotacceptabletoimproveunreasonablytheeffectivenessoftasksbecauseitwillincreasethecosts.
3ReliabilityAnalysisofProcedureSubsystem
3.1ReliabilityCalculationofProcedureSubsystem
Productasconstructionoutputismanufacturedaftertheconstructionprocedures;thereforetheunitofconstructionsystemisconstructionprocedure.Inthecontextofreliabilityanalysis,theunitconstructionprocedurespartitioningthewholeprojectcanbemodeledasaseries-parallelsystem;thesub-divisionproceduresforaunitconstructionprocedurecanalsobemodeledasseries-parallelreliabilitysystem.Basedonthereliabilityanalysistheory,theprobabilityofreliabilityofaseriesconnectionsystemwheneveryprocedureisindependentistheproductofprobabilityofeachprocedure:
⑸
wherejisnumberofconstituentconstructionproceduresoftheseriesconnectionsystem,j=1,2,…,n.
Becauseeachpartoftheparallelsysteminfluencesthefeasibilityofconstructionschemeandthusthereliabilityofconstructiondirectly,whichisaparallelconnectionnon-redundantsystem,therefore,theprobabilityoffailureofaparallelconnectionconstructionsystemistheminimumoftheprobabilitiesofbranches,i.e.:
Pt=min﹛Pk,k=1,2,3,……﹜⑹
WherePkistheprobabilityoffailureofkthbranch.
comestoaseries-parallelsystem,thereliabilityofthewholesystemiscalculatedaftertheprobabilityofseriesconnectionbranchandparallelconnectionbrancharecalculatedbyequation(5)and(6)separately.
3.2ReliabilityImprovementApproachestoProcedureSubsystems
Mostoftenmodeledreliabilitysystemsforconstructionproceduresareseries,parallelandseries-parallel.Fortheconstructionprocedurewithseriesbranches,theprobabilityofreliabilityistheproductofthereliabilityofeachconstituentsystemasshowninEq.(5).Herein,toenhancethereliabilityofthesystem,thereliabilityofeachconstructionproceduremustbeenhanced.Inaddition,emphasisshouldbeputonthoseconstructionprocedures,thereliabilityofwhichcanbeguaranteedbysomeeasymeasures.Fortheconstructionprocedurewithparallelconnection,however,itisknownfromEq.(6)thatnotonlyshouldweenhancethereliabilityofthesystemaswedoforseriesconnectionsystem,butalsoweshouldminimizethedifferenceofeachconstructionproceduretooptimizethemeasuresforreliabilityimprovement.
Inaddition,numberofconstructionproceduresofproceduresubsysteminfluencesthereliabilityoft