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Patterson,NY
SpecialfiresprinklersysteminstallationguidanceintendedtoguardagainstdamageduetoearthquakesfirstappearedintheNorthAmericansprinklerinstallationstandardin1947,andwaslargelybasedonexperienceintheLongBeachearthquakeof1930.AtthattimemanybuildingcodesinuseintheUnitedStatesdidnotevenaddressthesubjectofearthquakes.InsurancereportsoftheLongBeachearthquakehadindicated90damagedsprinklersystems.Thefirstguidance,containedonlyintheappendix,calledfor1to2inchesclearancearoundpipes,flexiblecouplingsinrisersand“someformoflateralandlongitudinalbracing”forfeedandcrossmains.
Inthe1951editionrequirementswereplacedinthebodyofthestandardforplacementof
longitudinalandlateralbraceswithspacingindicatedas“30to40ft”,amaximum
slendernessratioofbracemembersof200,andflexiblecouplingsonriserswhereitwas
necessarytoprotectsystemsagainstearthquakes.Thestatedintentwastolaterallybrace
for50%ofweightofwater-filledpipingandattachments.
Inthedecadessincethendeliberateeffortshavebeenmadetoclarifytherulesand
improveprotectionwithinthetextofNFPA13–InstallationofSprinklerSystems,but
alwayswiththeintentofaddressing“how”systemsaretobeprotectedagainst
earthquakes,not“where”suchprotectionistobeprovided.Itwasrecognizedthat
buildingcodesandotherauthoritiesmadethebasicdecisionswithregardtothelocation
ofearthquake-proneareas.
AlthoughtheearliestguidancecontainedinNFPA13camefromtheinsuranceindustry
inthewesternstates,theNFPACommitteeonAutomaticSprinklersformedan
EarthquakeProtectionSubcommitteein1985.Oneofthegoalsofthissubcommitteewas
todevelopameanstoaddressthebracingofsprinklersystemsinthesamemannerthat
theapplicationofsystemhydraulicshadbeenaccomplished.Althoughacomplex
subject,itwasbelievedthatmanyofthedesignaspectscouldbepre-engineeredinto
tablesandthenproperlyappliedbythetechnicianswhonormallylayoutanddetailfire
sprinklersystems.The1983standardcontainednoinformationonthesizingorfastening
ofbracingrelativetoloads.Amethodwasproposedin1984whereby“zonesof
influence”couldbeevaluatedtodeterminetotalloadsforproposedbracelocations.
Tableswereproposedfordeterminingmaximumbraceloadsandallowablefastenerloads
basedonsixdifferentcombinationsofbraceandfastenerorientationandanglefrom
vertical.
Thisconceptandtheaccompanyingtableswereacceptedintotheappendixof
thestandardinthe1987edition,andinthe1989editionthetableswereexpandedtonine
combinationsoforientationandangleandmovedintothebodyofthestandard.
2007StructuresCongress:
NewHorizonsandBetterPractices©
2007ASCE
CopyrightASCE2007StructuresCongress2007
Downloaded06Mar2009to202.118.74.100.RedistributionsubjecttoASCElicenseorcopyright;
seehttp:
//www.ascelibrary.orgTheNFPA13EarthquakeProtectionSubcommitteewasinplaceatthetimeoftheLoma
PrietaandNorthridgeearthquakesin1989and1994,andheldpublichearingsin
cooperationwiththeNationalFireSprinklerAssociationandtheSocietyofFire
ProtectionEngineersfollowingthoseeventsinordertoevaluatehowfiresprinkler
systemsperformedduringtheearthquakesandstodevelopsuggestionsforimprovements
totheprotectioncriteriawithinthestandard.
Ingeneral,theperformanceoffiresprinklersystemsinthoseearthquakeswasjudgedtobegood,withastrongcorrelationbetweenobservedfailuresanddeparturesfromtherulesofNFPA13.Oneareaacknowledgedtobeinneedofimprovementwastheinteractionofsprinklersandceilings;
impactofsprinklersagainstrigidceilingsresultedinaseveralhigh-profileincidentsinwhichanumberofsprinklersopenedandwaterdamageresulted.In1999theNFPAsprinklerprojectwasreorganized.ResponsibilitiesfortheearthquakeprotectionrulesweregiventoanewNFPATechnicalCommitteeonHangingandBracingofWater-BasedFireProtectionSystems,oneoffourseparatetechnicalcommitteescoordinatedthroughaTechnicalCorrelatingCommitteeresponsibleforNFPA13.Thisallowedthedirectinputofmoreearthquakeengineeringexpertiseintothestandarddevelopmentprocess.
Majorchangesinbuildingcoderequirementsforearthquakeprotectionhavetakenplaceinthepasttwentyyears,mainlyduetotheNationalEarthquakeHazardsReductionProgram(NEHRP)provisionsdevelopedwithfundingfromtheFederalEmergencyManagementAgency.TheNEHRPprovisionsinitiallyfoundtheirwayintothecodes
throughdirectadoption,