建筑屋面滑移雪荷载的模拟方法研究

316Vol.31No.620146June2014ENGINEERINGMECHANICS1902012-12-302013-05-22(51278368)(SLDRCE08-A-03)(1975)(E-mail:[e-mail]).(1985)(E-mail:[e-mail])(1957)(E-mail:[e-mail]).1000-4750(2014)06-0190-0711,21(1.2000922.250031)TU312Adoi:10.6052/j.issn.1000-4750.2012.12.1023METHODFORSIMULATINGSLIDINGSNOWLOADSONROOFSZHOUXuan-yi1,ZHANGYun-qing1,2,GUMing1(1.StateKeyLaboratoryofDisasterReductioninCivilEngineering,TongjiUniversity,Shanghai200092,China;2.ShandongProvincialCommunicationsplanningandDesignInstitute,Jinan250031,China)Abstract:Slidingsnowloadsareanimportantcomponentofsnowloadingonroofs.Asimulationmethodforslidingsnowloadsisdevelopedinthispaper.Firstly,basedonpreviouslydevelopedmassandenergybalancemodels,abuildingroofsnowmeltmodelisdeveloped,whichfocusesonthefeaturesofthesnowpack.Basedonthismodel,itisproposedthatthesufficientconditionforroofsnowslidingisthattheliquidwaterinthesnowexceedsthemaximumwatercapacityofsnow.Usingthemethodforcalculatingslidingsnowloadproposedinthepaper,simulationsoftheslidingsnowloadsonroofsinseveralrepresentativeareasinChinaareperformed,andtheinfluencesfromclimatefeaturesandshieldingeffectsofneighboringbuildingsareanalyzed.Atthesametimethecontributionsofavarietyofenergiestosnowslidingarepresentedquantitatively.Keywords:snowsliding;massandenergybalancemodels;buildingroofsnowmeltmodel;maximumwaterholdingcapacityofsnow;slidingsnowloadSack[1]LepageSchuyler[2]IsyumovMikitiuk[3]191[49]--11.13W/mU/(kJm2)[4]WUU0[4,9][4,9]ddnetnatlprUQSLLHEQQt(1)nSaLtLHlEpQ(/)rQ[4,9][4,9](rQ)21kJmhrnetQ[4,9]oddrsEWPPMWt(2)PrPsMoWEmhr11[4,9]1Fig.1Energyfluxesinvolvedinsnowmeltonaroof[4,9]([4,9][1011])[4,9][4,9]3DSSDSn[1213]192[1011]((1))(1)nSDPSASA(3)DPSASA()PSA0[10]PSA=1.0[14]()bbvzzvz(4)bzbvz()vzLepageSchuyler[2]io()/riQTTR(5)Ti/()To/()Ri/(m2KW1)RiK1iRK(6)K/(W/(m2K))[1517]1.2TsTTaU0[4,1819]UWTsT1.32[1]0[3]0()[2021](3%[22])21(=SURF&pageid=3)1951111201133160/2193//()3/313/142/272/121/281/1312/2912/1411/3011/1511/1/mm/3/313/142/272/121/281/1312/2912/1411/3011/15(%)11/1/(m/s)//()3/313/142/272/121/281/1312/2912/1411/3011/1511/1/mm/3/313/142/272/121/281/1312/2912/1411/3011/15/(%)11/1/(m/s)2Fig.2Meteorologicaldatafromasinglewinterfordifferentregions2.1()[1517]0.2W/(m2K)~1.5W/(m2K)0.4W/(m2K)0.4W/(m2K)10mB(α=0.16)Ti18()((3%))0%()1%2%3%4%5%7%9%80%()1%2%3%4%5%7%9%3%4%5%6%7%8%10%12%[3]350(2%)01234567890.00.10.20.30.40.50.6/(kN/m2)/(%)3(50)Fig.3Massperunitareaofslidingsnowasafunctionofratiobetweenoutflowandsnowwaterequivalence(50-yearreturnperiod)1943(3%)30%~3%2(3%[22])()2.21()iittitERE(7)itEti(itE(/))itRtitR60(6060)(4)(+)()()()44()051015202530354045()()()()()QbQp(El)(H)(LaLt)/(%)/(kJm2hr1)(Sn)4()Fig.4Ratioofcomponentsofenergytototalenergy(standardroof)SnQp(LaLt)LaQbQbHEl2.3()501020304050/mm/d11/111/1511/3012/1412/291/131/282/122/273/143/315Fig.5Snowwaterequivalentonroofthroughasinglewinter(Shenyang)195[3](6)6()0204060801000.00.10.20.30.40.50.60.70.8/kN/m2/6Fig.6Weightperunitareaofslidingsnowasafunctionofreturnperiod6500.31kN/m20.56kN/m20.19kN/m20.21kN/m20.25kN/m20.23kN/m20.56kN/m20.19kN/m2[14](50)70.00.10.20.30.40.50.60.70.80.91.07Fig.7Ratiobetweensnowslidingpressureandreferencesnowpressure72.4D[1213]DSR(SRDS)8DSR8DSRFig.8RatiobetweendirectsolarradiationandradiationSR8()DSR()0.5DSR(0.3)90.30.40.50.60.70.80.91.0/(%)02050801009Fig.9Slidingsnowpressuregrowthunderdifferentshieldingrate196(27%)(14%)3(1)--()(2)(3)14%~27%[1]SackRL,ArnholtzD,HaldemanJS.Slopedroofsnowloadsusingsimulation[J].JournalofStructuralEngineering,ASCE,1987,113(8):18201834.[2]LepageMF,SchuylerGD.Asimulationtopredictsnowslidingandlift-offonbuildings[C].SantaBarbara,California,ProceedingsoftheEngineeringFoundationConferenceonaMultidisciplinaryApproachtoSnowEngineering,1988.[3]IsyumovN,MikitiukM.Slidingsnowandicefromslopedbuildingsurfaces:Itsprediction,potentialhazardsandmitigation[C].WhistlerBC,Canada,Proceedingsofthe6thSnowEngineeringConference,2008.[4]TarbotonDG.Utahenergybalancesnowaccumulationandmeltmodel(UEB)[D].ComputerModelTechnicalDescriptionandUsersGuide,UtahWaterResearchLaboratoryandUSDAForestServiceIntermountainResearchStation,1996.[5]GustafssonD,StähliM,JanssonPE.Thesurfaceenergybalanceofasnowcover:Comparingmeasurementstotwodifferentsimulationmodels[J].TheoreticalandAppliedClimatology,2001,70:8196.[6]HockR.Temperatureindexmeltmodelinginmountainareas[J].JournalofHydrology,2003,282:104115.[7]OharaN,KavvasML.Fieldobservationsandnumericalmodelexperimentsforthesnowmeltprocessatafieldsite[J].AdvancesinWaterResources,2006,29:194211.[8]LetsingerSL,OlyphantGA.Distributedenergy-balancemodelingofsnow-coverevolutionandmeltinruggedterrain:TobaccoRootMountains,Montana,USA[J].JournalofHydrology,2007,336(1/2):4860.[9]ZeinivandH,SmedtFD.Predictionofsnowmeltfloodswithadistributedhydrologicalmodelusinga