2019年土木-建筑-外文翻译-外文文献-英文文献-消防自动喷水灭火系统抗震设计Word文件下载.doc

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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,