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EstimatingBasinEffectsUsingM9andRecentResearchforTallBuildingDesigninSeattle

COSMOSTechnicalSessionSusanChang,Ph.D.,P.E.INovember16,2018

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SeattleBasin

DatacourtesyofRichardBlakely

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TallBuildingsinSeattle(100+m,328+ft)

RainierSquareTower2020,850ft

F5Tower2017,660ft

ColumbiaCenter1984,933ft

RussellInvestmentsCenter2006,598ft

12013rd Avenue1988,772ft

SmithTower1914,462ft

FigurefromDougLindquist,HartCrowser

BackgroundSource:www.skyscrapercenter.com/city/seattle 31buildings31buildings

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March4,2013WorkshopChang,S.W.,Frankel.,A.D.,andWeaver,C.S.,2014,ReportonWorkshoptoIncorporateBasinResponseintheDesignofTallBuildingsinthePugetSoundRegion,Washington:U.S.GeologicalSurveyOpen-FileReport20-14-1196,28p.,https://pubs.usgs.gov/of/2014/1196/

• Basinamplificationfactorsfromcrustalgroundmotionmodels(amplificationfactorsafunctionofZ2.5 andZ1.0)• AppliedtoMCER fromPSHAforallEQsourcetypes

PhotobyDougLindquist,HartCrowser

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RecentResearchEffectofDeepBasinsonStructuralCollapseDuringLargeSubductionEarthquakesByMarafi,Eberhard,Berman,Wirth,andFrankel,EarthquakeSpectra,August2017

• BasinamplificationfactorsforsiteswithZ2.5 > 3km

Marafi etal.(2017)

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ObservedamplificationofspectralresponsevaluesforstiffsitesinSeattleBasinreferencedtoSewardParkstation–thinsoiloverfirmrockoutsideofbasin

2003underOlympics,M4.8

2001nearSatsop,M5.0

RecentResearch

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RecentResearchBroadbandSyntheticSeismogramsforMagnitude9EarthquakesontheCascadiaMegathrustBasedon3DSimulationsandStochasticSynthetics(Part1):MethodologyandOverallResultsByFrankel,Wirth,Marafi,Vidale,andStephenson,submittedtoBSSAJanuary2018,completedUSGSinternalreview

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USGS/SDCIMarch22,2018WorkshopAttendeesPeerreviewers• C.B.Crouse(AECOMSeattle)• SteveDickenson(NewAlbion)• IvanWong(Lettis Consultants)

GeotechnicalConsultants• DougLindquistandMichaelChamberlain(HartCrowser)• HamiltonPuangnakandMelanieWalling(GeoEngineers)• AliShahbazian andMattGibson(Shannon&Wilson)• RedaMikhailandFengLi(Golder)

GMMdevelopersandseismologists• NormAbrahamson(UCBerkeley)• KenCampbell(CoreLogic)• AndreasSkarlatoudis(AECOMLA)

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USGS/SDCIMarch22,2018WorkshopAttendeesUSGS/M9• ArtFrankel(USGS/M9)• ErinWirth(USGS/M9)• MarcEberhard(UW/M9)• SteveKramer(UW/M9)

SDCI• SusanChang• ScottPawling

OrganizationalRepresentatives• KevinAswegan(MKA,ASCE7SeismicCommittee)• AndyTaylor(KPFF,SEAWEEC)• DouglasBeck(CityofBellevue)

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Agenda• BasinfactorsfromGroundMotionModels

• HowbasintermsweredevelopedforcrustalGMMs• PresentationsbyCampbellandAbrahamson(Seyhancalledinforpartofworkshop)

• IncorporationofBasinResponseinSeattle• Whathavewebeendoingsincethe2013workshop?• PresentationsbyGeoEngineers andHartCrowser

• RecentResearch• EffectofDeepBasinsonStructuralCollapseDuringLargeSubductionEarthquakes,Marafi etal.,EQSpectra,August2017

• BroadbandSyntheticSeismogramsforM9EarthquakesontheCascadiaMegathrustbasedon3DSimulationsandStochasticSynthetics,Frankeletal.,submittedtoBSSAJanuary2018

• BasinAmplificationFactorsforCascadiaBasedonthe2011Tohoku,JapanEarthquake,Skarlatoudisetal.,11th NCEE,June2018(alsoUSGSFinalTechnicalReport,October2015)

• Site-specificMCERResponseSpectraforLosAngelesRegionbasedon3DNumericalSimulationsandtheNGAWest2Equations,Crouse,11th NCEE,June2018

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Agenda• CodeUpdatesandStructuralDesign

• ASCE7-16and7-22(C.B.Crouse)• Upcomingstructuralcodechanges(AndyTaylor)• Structuralimpacts(KevinAswegan)

• DiscussionandRecommendations

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DiscussionandRecommendations• Weshouldcontinuewiththegeneralprocedurefrom2013workshop:MCER spectrummultipliedbybasinamplificationfactor.• Basinamplificationfactorsdevelopedfromcrustalearthquakesarenotappropriateforsubductionzoneearthquakes(differentfrom2013workshop)

Copyright2015CoreLogic,Inc.Allrightsreserved.

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DiscussionandRecommendations

FiguresfromN.Marafi 2

Basin Amplification

Z2.5,REF = 1.0

Z2.5,REF = 3.0

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NewConsensusApproachforDevelopmentofBAFs• InterfaceSubductionHazard(basedonrecordedmotionsandM9project)• BAF=1atT=0sec• BAF=2atT> 2sec

• DeepIntraslab Hazard• Userecordedgroundmotionsfromlocalandregionalearthquakes(e.g.M6.8Nisqually,M6.4VancouverIsland)

• ShallowCrustalHazard• UsebasinfactorsfromCampbellandBozorgnia (2014)GMM

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ExampleSpectra• Increasefromoldtonewspectra

• T=1sec,10%

• T=2sec,24%

• T=5sec,15%

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ImplementationofMarchWorkshopResults

• Structuralcommunityconcernedaboutimmediateimplementation• TelephoneconferenceMay16withgeotechnicalandstructuralpeerreviewers,geotechnicalconsultantstodiscusspotentialdelayinimplementation• Scheduleofimplementation

• Director’sRule20-2018• December1,2018• Alldesignsusingsite-specificgroundmotionproceduresshallincorporatebasineffects

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Onthehorizon…• NGASubductionGMMs

• Willtheyincludebasinterms?• GeotechnicalandseismologicalcommunitywillneedtoevaluateapplicabilitytotheSeattleBasin

• HowdoweincorporateNGASubductionandM9results?• HadinitialdiscussionduringMarch2018workshop

• 2018NationalSeismicHazardMapupdatetoincludebasinfactorsfrom2013SDCI/USGSworkshop

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QUESTIONS?

SusanChang,Ph.D.,P.E.susan.chang@seattle.gov206.386.9785

www.seattle.gov/sdci

DatacourtesyofRichardBlakely(USGS)