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1、TheEvolutionofSeismicDesignofFireSprinklerSystemsRussellP.Fleming,P.E.ExecutiveVicePresidentNationalFireSprinklerAssociationPatterson,NYSpecialfiresprinklersysteminstallationguidanceintendedtoguardagainstdamageduetoearthquakesfirstappearedintheNorthAmericansprinklerinstallationstandardin1947,andwasl

2、argelybasedonexperienceintheLongBeachearthquakeof1930.AtthattimemanybuildingcodesinuseintheUnitedStatesdidnotevenaddressthesubjectofearthquakes.InsurancereportsoftheLongBeachearthquakehadindicated90damagedsprinklersystems.Thefirstguidance,containedonlyintheappendix,calledfor1to2inchesclearancearound

3、pipes,flexiblecouplingsinrisersand"someformoflateralandlongitudinalbracing"forfeedandcrossmains.Inthe1951editionrequirementswereplacedinthebodyofthestandardforplacementoflongitudinalandlateralbraceswithspacingindicatedas"30to40ft",amaximumslendernessratioofbracemembersof200,andfl

4、exiblecouplingsonriserswhereitwasnecessarytoprotectsystemsagainstearthquakes.Thestatedintentwastolaterallybracefor50%ofweightofwater-filledpipingandattachments.InthedecadessincethendeliberateeffortshavebeenmadetoclarifytherulesandimproveprotectionwithinthetextofNFPA13-InstallationofSprinklerSystems,

5、butalwayswiththeintentofaddressing"how"systemsaretobeprotectedagainstearthquakes,not"where"suchpisotecbioiprovided.Itwasrecognizedthatbuildingcodesandotherauthoritiesmadethebasicdecisionswithregardtothelocationofearthquake-proneareas.AlthoughtheearliestguidancecontainedinNFPA13ca

6、mefromtheinsuranceindustryinthewesternstates,theNFPACommitteeonAutomaticSprinklersformedanEarthquakeProtectionSubcommitteein1985.Oneofthegoalsofthissubcommitteewastodevelopameanstoaddressthebracingofsprinklersystemsinthesamemannerthattheapplicationofsystemhydraulicshadbeenaccomplished.Althoughacompl

7、exsubject,itwasbelievedthatmanyofthedesignaspectscouldbepre-engineeredintotablesandthenproperlyappliedbythetechnicianswhonormallylayoutanddetailfiresprinklersystems.The1983standardcontainednoinformationonthesizingorfasteningofbracingrelativetoloads.Amethodwasproposedin1984wherebyzonesofinfluence&quo

8、t;couldbeevaluatedtodeterminetotalloadsforproposedbracelocations.Tableswereproposedfordeterminingmaximumbraceloadsandallowablefastenerloadsbasedonsixdifferentcombinationsofbraceandfastenerorientationandanglefromvertical.Thisconceptandtheaccompanyingtableswereacceptedintotheappendixofthestandardinthe

9、1987edition,andinthe1989editionthetableswereexpandedtoninecombinationsoforientationandangleandmovedintothebodyofthestandard.2007StructuresCongress:NewHorizonsandBetterPractices?2007ASCECopyrightASCE2007StructuresCongress2007Downloaded06Mar2009toRedistributionsubjecttoASCElicenseorcopyright;seeNFPA13

10、EarthquakeProtectionSubcommitteewasinplaceatthetimeoftheLomaPrietaandNorthridgeearthquakesin1989and1994,andheldpublichearingsincooperationwiththeNationalFireSprinklerAssociationandtheSocietyofFireProtectionEngineersfollowingthoseeventsinordertoevaluatehowfiresprinklersystemsperformedduringtheearthqu

11、akesandstodevelopsuggestionsforimprovementstotheprotectioncriteriawithinthestandard.Ingeneral,theperformanceoffiresprinklersystemsinthoseearthquakeswasjudgedtobegood,withastrongcorrelationbetweenobservedfailuresanddeparturesfromtherulesofNFPA13.Oneareaacknowledgedtobeinneedofimprovementwastheinterac