REXEL v 3.5 beta Computeraidedcode-basedrealrecordselectionforseismicanalysisofstructures

©IunioIervolino,CarmineGalassoandEugenioChioccarelli2008-2013DipartimentodiStruttureperl’Ingegneriael’Archiettura,UniversitàdegliStudidiNapoliFedericoII,Italy

TUTORIAL01/30/13Version

Forinformation:iunio.iervolino@unina.it

P a g e |2

Summary

Preface....................................................................................................................................................4

Guidetoinstallation................................................................................................................................7

Guidetostepbystepselection................................................................................................................8

Definitionofthetargetspectrum........................................................................................................8

Lookingatdisaggregation...................................................................................................................8

Lookingatconditionalhazard.............................................................................................................9

Selectionoftherecordstobeconsideredinthecompatibilityanalysis(Preliminarysearch)...........11

Spectralmatchingparametersandanalysisoptions........................................................................12

OutputManagement............................................................................................................................14

EXAMPLES.............................................................................................................................................16

Case1:Cosenza,SLD.........................................................................................................................17

Case1a:Selectionofasetof7-unscaledaccelerograms..............................................................17

Case1.1a:Selectionofasetof7-unscaledaccelerogramschoosingrangesofmagnitudeanddistance.........................................................................................................................................17

Case1.2a:Selectionofasetof7-unscaledaccelerogramschoosingrangesofmagnitude,distanceandepsilon......................................................................................................................18

Case1b:Selectionoftwosetsof7-unscaledaccelerogramswhichdon’tshareevents................19

Case1c:Selectionofthreesetsof7-unscaledaccelerogramswhichdon’tsharerecordings.......21

Case2:Cosenza,SLC..........................................................................................................................23

Case2a:Selectionofasetof7-scaledaccelerogramsaccordingtothehazarddisaggregationintermsofPGAandSa(T=1.0sec).....................................................................................................23

Case3:Forlì,SLV................................................................................................................................25

Case3a:Selectionofasetof7-unscaledaccelerogramsbyusingtheItalianAccelerometricArchiveITACA................................................................................................................................25

Case3b:Selectionofasetof7-unscaledaccelerogramsforspatialanalysis(3components).....25

Case4:Sant’AngelodeiLombardi,SLV.............................................................................................30

Case4a:Selectionofasetof7-unscaledaccelerogramsbyusingdisaggregationforSa(T=1.0s)........................................................................................................................................................30

Case5:Napoli-Ponticelli,SLC............................................................................................................33

Case5a:Selectionofasetof7-unscaledaccelerogramsbyusingseconddisaggregationmodeforSa(T=1.0s)..........................................................................................................................................33

Case5b:Selectionofasetof7-scaledaccelerogramsbyusingIDconditionalhazard......................35

P a g e |3

Case5c:SelectionofanindividualrecordusingPGVasparameterforpreliminarydatabasesearch............................................................................................................................................................36

Case5d:Selectionofasetof7-unscaledaccelerogramsusingPGAasparameterforpreliminarydatabasesearch................................................................................................................................37

Case6:ASCEspectrumandSIMBADdatabase.................................................................................38

Caso6a:Selectionofasetof30-scaledaccelerograms................................................................38

AppendixA............................................................................................................................................40

REFERENCES..........................................................................................................................................42

PrefaceREXEL 3.5 beta, available on the internet on the website of the Italian consortium ofearthquakeengineeringlaboratories:RetedeiLaboratoriUniversitaridiIngegneriaSismica–ReLUIS(http://www.reluis.it/),allowstodefinethedesignspectraaccordingtotheEurocode8(EC8–CEN,2003),thenewItalianBuildingCode(NIBC–CS.LL.PP.,2008),ASCEStandardASCE/SEI 7-05 (ASCE, 2006) or completely user-defined. Based on these spectra, thesoftwareallowstosearchforsetsof7recordscompatible, intheaverage,withthem,andwiththeminimumdispersionofindividualspectra(tofollow).The datasets included in REXEL are the European Strong-motion Database (ESD) (lastupdated on July 2007), whose URL is http://www.isesd.cv.ic.ac.uk, the ItalianAccelerometric Archive (ITACA) (last updated on October 2010) by Istituto Nazionale diGeofisicaeVulcanologia (INGV),whoseURL ishttp://itaca.mi.ingv.it and thedatabasewithSelected InputMotions for displacement-Based Assessment and Design (SIMBAD v 3.0)(lastupdatedonJanuary2013)developedbySmerziniandPaolucci(2011)intheframeworkof the ReLUIS 2010-2013 project (http://www.reluis.it/), in the task referring toDisplacementBasedApproachesforSeismicAssessmentofStructures.All the records contained in REXEL satisfy the free-field conditions andwere producedbyearthquakesofmomentmagnitude largerthan4(5 inthecaseofSIMBAD).FiguresbelowshowdistributionsregardingESD, ITACAandSIMBADinREXEL; therecordsofSIMBADareclassified by the countries they come from. In the case of ITACA the Eurocode 8 soilclassificationisthatfromtask2oftheprojectS4ofINGV(http://esse4.mi.ingv.it/)andmayberevisedinthefuture.WARNING: ESD, ITACA and SIMBAD have records in common although with differentseismologicalprocessing.Therewasnoattemptbytheauthorstohomogenize/combinethethreedatabases,whichareseparatedinthesoftware.Moreover,thethreedatabasescoverdifferent magnitude and distance ranges, therefore the appropriate database to use insearchesmayalsodependonwhichrangeofmagnitudeanddistanceone is interested in,seefiguresbelow.ThesourcesofgroundmotionrecordsinSIMBADaregiveninTable1.

P a g e |5

MagnitudevsepicentraldistancedistributionforSIMBADdatasetonwhichREXELoperates.TherecordsaregroupedbysiteclassaccordingtoEC8classification.

Table1SourcesofstronggroundmotionrecordsoftheSIMBADdatabase.

Country/area

No.ofrecords Source Website

Japan§ 220K-NET http://www.k-net.bosai.go.jp/

KiK-net http://www.kik.bosai.go.jp/

Italy 83ITalianACcelerometricArchive:ITACA http://itaca.mi.ingv.it/

DepartmentofCivilProtection http://www.protezionecivile.gov.it/

USA 44

CenterforEngineeringStrongGroundMotionData:CESMD http://strongmotioncenter.org/

PEERStrongMotionDatabase http://peer.berkeley.edu/peer_ground_motion_database

U.S.GeologicalSurveyNationalStrongMotionProject:NSMP http://nsmp.wr.usgs.gov/

Europe 18 EuropeanStrong-MotionDataBase:ESMD http://www.isesd.hi.is/

NewZealand 77 InstituteofGeologicalandNuclear

Sciences:GNS http://www.geonet.org.nz

Turkey 15 TurkishNationalStrongMotionProject:T-NSMP http://daphne.deprem.gov.tr

Greece 7 InstituteofEngineeringSeismologyandEarthquakeEngineering http://www.itsak.gr/en/head

Iran 3 IranStrongMotionNetworkISMN http://www.bhrc.ac.ir/

§Recordsfromthe1995Hyogo-kenNanbuearthquakecomefromtheESG98datadistributionCD-ROMfortheKobeSimultaneousSimulation

P a g e |6

IfyouuseREXEL,pleaseciteas:IervolinoI.,GalassoC.,CosenzaE.(2010).REXEL:computeraidedrecordselectionforcode-basedseismicstructuralanalysis.BulletinofEarthquakeEngineering.

8:339-362,DOI10.1007/s10518-009-9146

REXELandthistutorialmaybeusedanddistributedforfreewhiletheirmodificationandcommercializationarenotauthorized.Theauthorshavemadeeveryeffortinordertoensurethe

accurateworkingofthesoftware;however,anyresponsibilityisdeclinedforwrongresults.

Guidetoinstallation1.InstallationofMATLABComponentRuntime(MCR)v7.11REXELwasdevelopedinMATLABenvironment;foritsusetheMATLABComponentRuntime(MCR)7.11isrequired.PleaselaunchtheMCRInstaller.exefileandfollowtheinstructionsofthe installation procedure. REXEL requires a specific version of MATLAB. If you have adifferentversionofMATLAB,itwillnotworkwithREXEL;forthisreason,youmustinstalltheMCR. TheMATLAB Component Runtime is a free redistributable that allows you to runprograms written in a specific version ofMATLAB without installing theMATLAB versionitself.ThereisnoharminhavingMATLABandtheMCRinstalledsimultaneously,orinhavingmultipleversionsofeachoneinstalled.

Imageoftheuserinterfaceofthesoftware2.InstallationofREXELv3.5betaInordertoinstallREXEL,pleaselaunchREXELInstaller.exefileandfollowstheinstructionsoftheinstallationprocedure.InordertoremoveREXEL,pleaseselectPrograms>REXELv3.5beta>UninstallREXEL3.5betaandfollowtheinstructionstocompletetheprocedure.

P a g e |8

GuidetostepbystepselectionThestepsneeded tosearch real recordssetscompatiblewithagiven target spectrumaredescribedbelow.

�DefinitionofthetargetspectrumFirstofall,itisnecessarytobuildtheaccelerationelasticresponsespectrumforthesiteofinterest [Buildcodespectrum].To thisaim, ifonewants tomakeaselectionaccording totheItalianBuildingCodespectra,itisnecessarytoenterthegeographicalcoordinatesofthesite, longitude and latitude in decimal degrees, and specify, through a drop-downmenu,developed in accordance with the requirements of code, the Site Class, the Topographiccategory,NominalLife,FunctionalTypeandtheLimitStateofinterest.For the Eurocode 8 spectra, it is necessary to specify only the anchoring value of thespectrum,ag,andthegroundtype(seealsoIervolinoetal.,2010a).Thevalueofagcanbedefinedmanuallybytheuseror,inthecaseofsitesontheItalianterritory,canbederivedautomaticallyfromthegeographicalcoordinatesofthesite(agvaluesusedinthesoftwarearethoseofNIBC).For ASCE Standard, the code specification requires three parameters to construct thespectrum,asfollow:Ss=shortperiodspectralacceleration(T=0.2s),S1=1speriodspectralaccelerationandTL=thetransitionperiodbetweenconstantspectralvelocityandconstantspectraldisplacementregionsofthespectrum.Moreover,thesiteclasshastobespecified;seethecodeforfurtherdetails.A fourthalternative is thepossibilityofusinga referencespectrumcompletelydefinedbytheuser[Userdefinespectrum].In addition, it is necessary to specify the component of the earthquake that will beconsidered. The two orthogonal independent components that describe the horizontalmotion (X and Y) are characterized by the same elastic response spectrum, while thecomponentthatdescribestheverticalmotion(Z)ischaracterizedbyaspecificspectrum.ItispossibletoselectX,YandZforfindingthreedimensionalcombinationsofmotion.IfthespecifiedcoordinatesdonotfallintoanodeofthereferencegridofNIBC,thevaluesof the parameters useful for the definition of the target spectrum are automaticallycalculatedasaweightedaverageofthevaluesthattheparameterofinterestassumedintheverticesoftheelementarymeshcontainingthesiteunderexamination,usingasweightstheinverse of the distances between the site and the four nodes, as specified in Annex A ofNIBC.LookingatdisaggregationDisaggregationisaprocedurewhichallowstoidentifythecontributiontothehazardofeachvariable(giventheexceedanceofthegroundmotionintensitymeasurecorrespondingtothereturnperiodofinterest):e.g.,magnitude(M),sourcetositedistance(R)andepsilon1(e ).Contributionsaredependentonhazardassessmentofthesite,spectralordinatesandreturnperiod.REXELprovidesdisaggregationresultsofeachItaliansiteforfourspectralordinates,1Fordefinitionandfurtherinformationaboute pleaseseeAppendixA.

P a g e |9

i.e.0second(PGA),0.5,1.0and1.5secondandforfourreturnperiods,i.e.50yr,475yr,975yrand2475yr.Foralldifferentreturnperiods,REXELprovidesautomaticallyresultsofthecloserreturnperiod.Tovisualizedisaggregationdistribution,theusermustselectthespectralordinateofinterestand the desired couple of variables (M and R or M and e ) and press the button[Disaggregation].Disaggregation can provide indications about the intervals to be used in record selection(seenextsection).Usingdisaggregationresultsfollowingpointshavetobeconsidered:1. OfficialItalianhazarddataanddisaggregationresults(onlyforPGA)areprovidedbyINGV

and are available at the web site http://esse1-gis.mi.ingv.it. Disaggregation resultsprovidedbyREXELrefertoaspecificindependentstudy.

2. ParametersofdisaggregationanalyseshavebeenfittedforthewholeItalianregionandresultshavebeenconsideredgenerallyreliableevenifinsiteswithlowseismicity,hazardevaluation (apreliminary step fordisaggregationanalysis) canbe lessaccuratebecausethesoftwareisnotabletocapturehazardvariationswithreturnperiod.Asconsequence,alsodisaggregationresultsdonotvarywithreturnperiodandaparticularattentionhastobeused.Intheseconditions,approximationis lowerforhigherreturnperiods.REXELshowsawarningforallthesecases.

3. Disaggregationplotssuggestthebestintervalsofmagnitude,distanceand e forrecordselectionbutrecords’availabilityisnotinsured.Moreoverthechoiceoftherightintervalsisuptousers.

ForfurtherdetailsandanytechnicalaspectaboutdisaggregationanalysisrefertoIervolinoetal.(2011)andConvertitoetal.(2009).LookingatconditionalhazardAcceleration-basedintensitymeasures(IMs,e.g.,spectralordinates)havebeenshowntobeimportantandusefulintheassessmentofstructuralresponseofbuildings.However,thereare cases inwhich it is desirable to account for other groundmotion IMs,while selectingrecords.Forexample,althoughitisgenerallybelievedthat,undersomehypotheses,integralIMsassociatedtodurationarelessimportantforstructuraldemandassessmentwithrespectto peak quantities of ground motion, there are cases in which the cumulative damagepotentialoftheearthquakeisalsoofconcern.An easy yet hazard-consistent way of including secondary IMs in record selection isrepresented by the conditional hazard curves (ormaps); i.e., curves of secondary groundmotionintensitymeasuresconditional,inaprobabilisticsense,tothedesignhazardfortheprimaryparameter.Toillustratetheconditionalhazardconcept,inthestudyofIervolinoetal.(2010b)thejointdistribution of PGA and a parameter which may account for the cumulative damagepotentialofgroundmotion,wasinvestigated.The chosen energy related measure is the so-called Cosenza and Manfredi index (ID),Equation (1), the ratio of the integral of the acceleration squared to the PGA and peakgroundvelocity(PGV).

( )2

0

Et

D

a t dtI

PGA PGV=

×ò (1)

REXEL 3.5 beta includes the ID conditional hazard results, suggesting to the user the

P a g e |10

distribution(intermsofcomplementarycumulativedensityfunctions)ofIDvalue(forItaly)giventhedesignPGA(i.e.theanchoringvalueofthetargetspectrum).MoreoverREXEL3.5includesalsoconditionalhazardforPGVandNp,beingthelatteraproxyforspectralshapeparameter defined in Equation (2). This should allow for improving record selection forearthquake engineering applications in a hazard consistent manner yet easily viable forpractitioners.

[ ] ( )1 2 1 1 2, 0.5; 1.0avgNp Sa T T Sa T T T= = = (2)For further details and any technical aspect about conditional hazard analysis refer toIervolinoetal.(2010b),BojòrquezandIervolino(2011)andChioccarellietal.(2012).

P a g e |11

� Selection of the records to be considered in the compatibilityanalysis(Preliminarysearch)The user may select the records of database (ESD or ITACA, both contained in REXEL)correspondingtoagivenrangeof:

1. M(momentmagnitude forA-Dsiteclass recordsofESD, localmagnitude forEsiteclass records; moment magnitude for all ITACA records) and R (epicentral), inkilometers(e.g.thischoicemaybeguidedbydisaggregationofhazard);

2. M,Rande (e.g.thischoicemaybeguidedbydisaggregationofhazard);3. peakgroundacceleration(PGA)ofhorizontalcomponentsofmotion,infractionofg,

theaccelerationofgravity;4. peak ground velocity (PGV) of horizontal components of motion, in m/s (e.g. this

choicemaybeguidedbyconditionalhazard);5. Cosenza and Manfredi index (ID) (e.g. this choice may be guided by conditional

hazard)ofhorizontalcomponentsofmotion;6. AriasIntensity(IA)ofhorizontalcomponentsofmotion,inm/s;7. Np(e.g.thischoicemaybeguidedbyconditionalhazard).

SeeforexampleCosenzaandManfredi(2000)foracompletereviewofthegroundmotionparametersthatcanbeassumedasstructuralandnon-structuraldamagemeasures.Tothisaim,theusermustspecifytheintervals[min,max]ofthegroundmotionparameterofinterestinwhichhewantstheaccelerogramsfallandthedatabaseofinterest.Aparameterthatisdesirabletoincludeinrecordselectionisthesiteclassification,affectingboth theamplitudeandshapeof response spectra.However, specifyinga closematch forthisparameter inrecordselectionmaynotalwaysbefeasible,becauseforsomesoftsoils,onlyafewrecordsareusuallyavailable.Moreover, ifthespectralshapeisassignedbythecode,thesiteclassofrealrecordsmaybeofsecondaryimportance.In lightof theseconsiderations, theremaybecases inwhich itmaybeuseful to relax thematchingcriteriaforsiteclassification.Therefore,inREXELitispossibletoselectrecordsfromSameastargetspectrumsoilorfromAny site class. This, as shown in the following, should help to overcome some of theproblemswhenforspecificsiteconditionsitishardtofindspectrummatchingsets.Then,thesoftwarereturnsthenumberofrecords(andthecorrespondingnumberofevents)availableintheserangesandtobeconsideredinthecompatibilityanalysis.After theseboundsaredefinedandconfirmed[Checkdatabase], thesoftwarereturnsthenumber of records (and the corresponding number of originating events) available in theintervals.Thislistconstitutestheinventoryofrecordsinwhichtosearchforsuitesofsevenwhichare intheaveragecompatiblewiththecodespectraofstep1above.Thesespectramayalsobeplotted[Preliminaryplot]alongwiththereferencespectrumtohaveapictureofthespectraREXELwillsearchamong.

P a g e |12

�SpectralmatchingparametersandanalysisoptionsInthissteptheparametersrelatedtothespectralcompatibilityaredefined.Inwhichperiodrange,[T1,T2],thetargetspectrumhastobematchedhastobedefinedfirst.T1andT2canbeanypair inthe0s–4srange.Secondly,thetolerancesallowedinspectralmatchingarerequired. This means the user has to specify the maximum deviations (lower and uppertolerances) in percentage terms that the average spectrum of the combination can havewithrespecttothetargetinthespecified[T1,T2]range.EC8,forexample,explicitlystatesthattheaverageelasticspectrummustnotunderestimatethecodespectrum,witha10%tolerance(lower limit)butdoesnotprovideany indicationabout the upper limit. It is economically viable to reduce as much as possible theoverestimationofthespectrumandthisiswhyalsoanupperlimitwasintroducedinREXEL.In this phase is also possible to select the Scaled records option, which corresponds tochoosewhethertosearchforunscaledorscaledrecordsets.Infact,REXELallowstoobtaincombinationsofaccelerogramscompatiblewiththecodespectrumwhichdoesnotneedtobescaled,but italsoallowschoosingsetsofaccelerogramscompatiblewiththereferencespectrumiflinearlyscaled.Ifthissecondoptionischosen,theuserhavetochecktheScaledrecords box, which means the spectra of the list defined in step 2 are preliminarilynormalizeddividingthespectralordinatestotheirPGA.Combinationsofthesespectraarecomparedtothenon-dimensionalcodespectrum.Ifthisoptionisselecteditisalsopossibleto specify themaximummean scale factor (SF) allowed; REXEL will discard combinationswithanaverageSFlargerthanwhatdesiredbytheuser.Theusercanalsoselecttheoption I’mfeeling lucky inordertostoptheanalysisafterthefirstcompatiblecombinationisfound.Thisoption,inmostcases,allowstoimmediatelygeta combination compatible with the reference spectrum, otherwise, the search forcompatible combinations may take a very long time (as warned by the software).Alternatively, the maximum number of compatible combinations to find after which thesearchhastostop,canbespecified.

P a g e |13

�CombinationsearchAtthispointtheinitiallistofrecordsandtheanalysis’parametersaresetanditispossibletodecidewhichkindofsearchtoperform.Thesoftwaresearchesfor:(a) 71-componentaccelerograms [7records (1component)]whoseaveragematches the

target spectrum in the specified range of periods and with the provided upper- andlower-bound tolerances. The found combinations can be applied in one direction forplaneanalysisofstructures2;

(b) 7pairsofaccelerograms[7records(2components)].Thisoptionallowstosearchfor14

recordswhichare72-componentsrecordings(bothXandYcomponentsof7recordingstationsonly),whichonaveragearecompatiblewiththetargetspectrum;thiskindofsearchisforcasesinwhichhorizontalmotionhastobeappliedinbothdirectionsofa3Dbuilding;

(c) 7tripletsofaccelerograms[7records(3component)]whichincludethetwohorizontal

andtheverticalcomponentofsevenrecordingstations(i.e.,21recordswhicharetheX,YandZcomponentsof7 recordingstationsonly) for full3Danalysis. In thiscase, theselection proceeds in two sub-steps: first, the combinations compatible with thehorizontal component of the code spectrum are found, exactly as case (b); then, thesoftwareanalyzestheverticalcomponentsofonlythosehorizontalcombinationswhichhave been found to be compatiblewith the code spectrum, and verifies if the set oftheir seven vertical components are also compatiblewith the vertical code spectrum.The tolerances and period ranges in which average spectral matching of verticalcomponents may be different from that regarding horizontal components and maydefinedbytheuserafterthehorizontalanalysishasfinished.

(d) 301-componentaccelerograms[30records(1component)]whoseaveragematchesthetarget spectrum in the specified range of periods and with the provided upper- andlower-bound tolerances. The found combinations can be applied in one direction forplaneanalysisofstructures3;

(e) 30pairsofaccelerograms[7records(2components)].Thisoptionallowstosearchfor

60 records which are 30 2-components recordings (both X and Y components of 30recordingstationsonly),whichonaveragearecompatiblewiththetargetspectrum;thiskind of search is for cases in which horizontal motion has to be applied in bothdirectionsofa3Dbuilding;

(f) Individual(horizontal)records[Individualrecordsearch]matchingthetargetspectrum

in the specified range of periods and with the provided upper- and lower-boundtolerances.

2 Note that this options applies alternatively to horizontal or vertical components ofmotion, although it isunlikelyoneislookingforasuitesofsevenverticalaccelerogramsonly.3 Note that this options applies alternatively to horizontal or vertical components ofmotion, although it isunlikelyoneislookingforasuitesofsevenverticalaccelerogramsonly.

P a g e |14

Animportantfeatureofthecodeisthatthelistofrecordsoutofstep2,whichisaninputforthisphase,areorderedwhentheanalysis is launchedinascendingorderoftheparameterdefined inEquation1,whichgives ameasureofhowmuch the spectrumof an individualrecord deviates from the spectrum of the code. In Equation (4), Saj(Ti) is the pseudo-accelerationordinateoftherealspectrumjcorrespondingtotheperiodTi,whileSatarget(Ti)isthevalueofthespectralordinateofthecodespectrumatthesameperiod,andNisthenumberofvalueswithintheconsideredrangeofperiods.

𝛿" =$%

&'( )* +&',-./0, )*&',-./0, )*

1%23$ (4)

Preliminaryorderingallowstoanalyzefirsttherecordswhichhaveasimilarspectralshapewithrespecttothetarget.Thisensuresthefirstcombinations,e.g.theonefoundwiththeI’mfeelingluckyoption,tobethosewiththesmallestindividualscatteringinrespecttothetargetspectrumasshowninthefollowingexamples.

OutputManagementAftertheanalysishasfinished,REXELreturns[Output>Results>Horizontal(Vertical)]alistof combinations whose average spectrum respects compatibility with the target in thechosenrangeofperiodsandwiththeassignedtolerance.The results of the analysis are sorted so that record combinations with the smallestdeviation from the spectrum of the code are the first of the output list, due to thepreliminaryorderingofrecordsaccordingtodj.Forallthecombinationsfound, it ispossibletocalculate[Output>Deviation>Horizontal(Vertical)]thedeviationofeachaccelerogramsofthecombinationcomparedtothetargetspectrum,andthedeviationoftheaveragespectrumofthecombinationcomparedtotheelastic response spectrum again according to Equation (2), in which the average spectralaccelerationoftherecordsreplacesSaj(Ti).Combinations returned are uniquely identified by a serial number; this code can be used[Output>Results>Plot&getset>Horizontal (Vertical) for7 recordsearchorOutput>Results>Plot&getrecordforindividualrecordsearch]tographicallydisplaythespectraofa specific combination of interest and obtain the spectra and acceleration time-historiesgroupedinacompressedfilebyREXEL.If a specific combination is chosen REXEL also returns themean value ofmagnitude anddistance of combination and the information about the individual records as retrieved byESD and ITACA that is, recording station, event (time, date and country), magnitude,distance,faultmechanism,etc[Output>Inforecordsplot].Inthecaseofnon-dimensionalsets,thescalefactorsofindividualrecordandthemeanscalefactorofthecombinationaregiven.Different2andDifferent3optionsAlthough both considered codes only require aminimum size for suites of 7 to considermeaneffectsonthestructure,itisknownhowthisnumbermayaffecttheconfidence(i.e.,the standard error) in the estimation of the structural response, which increases as the

P a g e |15

variabilityof individualrecordswithrespecttothetarget increases.Therefore, incaseonewantstoruntheanalyseswithalargernumberofrecordsREXELhastwooptionswhichbothareapplicabletothelistofresultsoftheanalysesdiscussedabove:- Different2allowstosearchwithinthelistofoutput,pairsofcombinations,i.e.,2setsof7

records of the type (a), (b), or (c) above, which have accelerograms from earthquakeevents which do not overlap. This allows to have a larger set of 14 one- or multi-componentrecords,spectrummatchingintheaverage,inwhichtherearenodominatingevents.Foreachfoundpairofsetsthesoftwarealsocomputesthemaximumdeviationofthe two original combination and this may be a parameter for choosing one pair inrespecttoanother;

- Different3allowstosearchwithinthelistofoutput,tripletsofcombinations(3setof7

one- or multi-component records) having no accelerograms in common although mayhave common events. This analysis provides sets of 21 record which, still, match thecode-requiredaveragespectralcompatibilitywiththegiventolerances.

RepeatsearchexcludingastationIn some cases, the analystmaywant to exclude a particular record appearing in a foundcombination.Tothisaim,REXELincludestheoptionRepeatsearchexcludingastation,whichallowstorepeattheperformedanalysisbyexcludingfromthelistofrecordscreatedinthePreliminarydatabasesearchoneormorewaveforms,inaniterativeway.DisplacementspectracompatibilityREXELallowstocheckthedisplacementspectracompatibilityforacombinationselectedtomatchapseudo-accelerationspectrum.ForeachperiodT,theelasticspectraldisplacementiscomputedasinversetransformationofelasticpseudo-spectralacceleration.

P a g e |16

EXAMPLESIn the following some illustrative examples of automatic selection of spectrum-matchingaccelerogram,usingREXELv3.5beta, are shownaswell as some “strategies”aimingat abetter selection, although for further details the reader should refer to Iervolino et al.(2010a).Ineachexample,thetargetspectraconsideredarebuiltaccordingtoNIBCevenifthesoftwareitselfpermitstodefineanytypeofEurocode8oruser-definedspectrum.TheexamplesrefertodifferentItaliansites,withdifferentgeographicallocation,siteconditions(accordingtoEC8)andhazardlevelasexpressedbythemaximumvalueofaccelerationonrock(ag)witha10%probabilityofexceedancein50years:§ Cosenza(SouthernItaly:latitude39,314°;longitude16.215°);§ Forlì(CentralItaly:latitude44.218°;longitude12.054°);§ Sant’AngelodeiLombardi(SouthernItaly:latitude40.8931°;longitude15.1784°);§ Ponticelli(SouthernItaly:latitude40.8516°;longitude14.3446°);§ Fuorigrotta(Naples,SouthernItaly:latitude40.829°;longitude14.191°);Theconsideredcasesare:Case1:Cosenza,SiteclassA,selectionforDamageLimitState(SLD)§ Case1a:selectionofasetofunscaledaccelerograms;

o Case 1.1a: Selection of a set of 7-unscaled accelerograms choosing ranges ofmagnitudeanddistance.

o Case 1.2a: Selection of a set of 7-unscaled accelerograms choosing ranges ofmagnitude,distanceandepsilon.

§ Case1b:selectionof twosetsofunscaledaccelerogramswhichdon’tshareearthquakeevents;

§ Case1c:selectionofthreesetsofunscaledaccelerogramswhichdon’tsharerecords.Case2:Cosenza,SiteclassA,selectionforCollapseLimitState(SLC)§ Case2:selectionofasetofscaledaccelerogramsaccordingtothehazarddisaggregation

intermsofPGAandSa(T=1.0s).Case3:Forlì,SiteclassB,selectionforOperabilityLimitState(SLV)§ Case 3a: selection of a set of unscaled accelerograms according to the hazard

disaggregationintermsofPGAandusingtheItalianAccelerometricArchive(ITACA).§ Case3b:Selectionofasetofunscaledaccelerogramsforspatialanalysis(3components).Case4:Sant’AngelodeiLombardi,SiteClassA,selectionforCollapseLimitState(SLV):§ Case 4: selection of a set of unscaled accelerograms according to the hazard

disaggregationintermsofSa(T=1.0s).Case5:Ponticelli,SiteClassB,selectionforCollapseLimitState(SLC):§ Case 5a: selection of a set of unscaled accelerograms according to the hazard

disaggregation(secondmode)intermsofSa(T=1.0s).§ Case5b:selectionofasetofscaledaccelerogramsbyusingconditionalhazard.§ Case 5c: selection of an individual record using PGV as parameter for preliminary

databasesearch.§ Case 5d: selection of a set of unscaled accelerograms using PGA as parameter for

P a g e |17

preliminarydatabasesearch.Case6:ASCEspectrumandSIMBADdatabase:§ Case6a:selectionofasetof30-scaledaccelerograms.

Case1:Cosenza,SLDInthefollowing,asetof7unscaledaccelerogramsforCosenza(Latitude39.314,Longitude16.215)consideringtheDamageLimitState(SLD),anominallifeof50years,functionaltypeII,topographiccategoryT1andsoiltypeA,accordingtoNIBC,isselected.Thefirststepistodefine the above mentioned parameters to determine the elastic acceleration responsespectrum,thatisthetargetspectrum(Figure1).

Figure1.DefinitionofthetargetspectrumforCosenza,case1Case1a:Selectionofasetof7-unscaledaccelerograms.The range of magnitude [4.8 – 7.3] and of distance [0 km– 50 km], obtained by thedisaggregationofseismichazardintermsofSa(T=1.0sec)withaprobabilityofexceedanceof63% in50years (Figure2a), allows to find2x219accelerograms (SoilA) from99differenteventsintheESD(Figure2c).Case1.1a:Selectionofasetof7-unscaledaccelerogramschoosingrangesofmagnitudeanddistance.Becauseofthelargenumberofaccelerogramsfound,thesearchmaytakeaverylongtime,so it isrecommendedtoreducethemagnitudeanddistanceranges,excludingtherecordswithamagnitudevaluelowerthan5.5andhigherthan6.5andwithadistancevalueshigherthan20.Inthiswayintervalswithhigherhazardcontributionareconsideredonly(anotherselection of records may be done considering higher values of distance and magnitude).With new intervals the software finds 2x31 compatible records from 15 different events(Figure 2d). In order to search for 1-component record sets, assigning a compatibilitytolerance between 10% and 30% in the range of period [0.15s – 2s], in few seconds the

P a g e |18

software finds 100000 compatible combinations and, by default, it displays the firstcombination(Figure3a).Case1.2a:Selectionofasetof7-unscaledaccelerogramschoosingrangesofmagnitude,distanceandepsilon.Inordertoconsidermoreinformationprovidedbydisaggregation,Mande distributioncanbe plotted by the software and ranges of magnitude, distance and e can be used foraddressingrecordselection.Morespecifically,withtherangeofmagnitudeequalto[4.8–7.3],distance [0km–50km]and e [0–1.5], thesoftware finds2x15compatible recordsfrom 14 different events (Figure 2e). In order to search for 1-component record sets,assigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s],infewsecondsthesoftwarefinds1147compatiblecombinationsand,bydefault,itdisplaysthefirstcombination(Figure3b).

(a) (b)

(c)

(d)

(e)Figure2.M-R(a)andM-e (b)disaggregationdistributionofthehazardintermsofSa(T=1.0sec)forCosenzaforareturnperiodof50years;anddefinitionofmagnitude,distance(candd)ande

(e)intervals.

P a g e |19

Figure3.FirstcombinationsfoundforCosenza,case1awithout(a)andwith(b)definitionofe range.

Case1b:Selectionoftwosetsof7-unscaledaccelerogramswhichdon’tshareevents.Inthefollowing,itissupposedonewantstoselecttwosetsof1-componetsgroundmotionsstartingfromthecase1.1a.TheusercanusetheoptionDifferent2; thisprovidespairsofsetswithrecordswhichcomefromnon-overlappingevents.Usingthisoptionthesoftwarefinds inabout fiveminutes100000compatiblepairsandopensDIVERSI.txt filebydefault,where the combinations are listed (Figure 4). To decrease the time of the analysis it issuggestedtoselectalowernumberofdesiredpairs.Referringtothefirstpairfound(Figure5aandb),thesoftwareprovides14registrationsfrom12differentevents.

Figure4.ResultsbyusingtheoptionDifferent2.

P a g e |20

a)Combination17372(Output>Plot&getrecords>17372)

b)Combination54092(Output>Plot&getrecords>54092)

Figure5.Thefirstpairofsets(Different2)foundforCosenza,case1b

Waveform ID Earthquake ID Station ID Earthquake Name Date Mw Fault MechanismEpicentral

Distance [km]EC8 Site

class1243 473 ST575 Izmit (aftershock) 13/09/1999 5.8 oblique 15 A5655 1825 ST2950 NE of Banja Luka 13/08/1981 5.7 oblique 10 A359 174 ST136 Umbria 29/04/1984 5.6 normal 17 A473 228 ST40 Vrancea 31/05/1990 6.3 thrust 7 A383 176 ST153 Lazio Abruzzo (aftershock) 11/05/1984 5.5 normal 14 A

4675 1635 ST2487 South Iceland 17/06/2000 6.5 strike slip 13 A7142 2309 ST539 Bingol 01/05/2003 6.3 strike slip 14 A

medie: 5.957143 12.85714286

Combinazione 17372

Waveform ID Earthquake ID Station ID Earthquake Name Date Mw Fault MechanismEpicentral Distance [km]

EC8 Site class

365 175 ST140 Lazio Abruzzo 07/05/1984 5.9 normal 5 A6342 2142 ST2556 South Iceland (aftershock) 21/06/2000 6.4 strike slip 20 A3802 1226 ST2368 SE of Tirana 09/01/1988 5.9 thrust 7 A365 175 ST140 Lazio Abruzzo 07/05/1984 5.9 normal 5 A149 65 ST26 Friuli (aftershock) 15/09/1976 6 thrust 12 A652 292 ST236 Umbria Marche (aftershock) 14/10/1997 5.6 normal 12 A

6326 2142 ST2496 South Iceland (aftershock) 21/06/2000 6.4 strike slip 14 Amedie: 6.0143 10.71428571

Combinazione 54092

P a g e |21

Case1c:Selectionofthreesetsof7-unscaledaccelerogramswhichdon’tsharerecordings.In the following it is supposed one wants to select three sets of 1-componets groundmotions,forthecase1a,withnorecordsincommon.TheusercanusetheoptionDifferent3; inabouttenminutesthesoftwarefinds100000tripletsofcompatiblecombinationsandopenstheDIVERSI.txtfilebydefaultwherethetripletsarelisted(Figure6).ThefirsttripletisshowninFigure7.

Figure6.ResultsbyusingtheoptionDifferent3.

a)Combination419(Output>Plot&getrecords>419)

Waveform ID Earthquake ID Station ID Earthquake Name Date MwFault

MechanismEpicentral

Distance [km]EC8 Site

class1243 473 ST575 Izmit (aftershock) 13/09/1999 5.8 oblique 15 A365 175 ST140 Lazio Abruzzo 07/05/1984 5.9 normal 5 A359 174 ST136 Umbria 29/04/1984 5.6 normal 17 A

3802 1226 ST2368 SE of Tirana 09/01/1988 5.9 thrust 7 A149 65 ST26 Friuli (aftershock) 15/09/1976 6 thrust 12 A359 174 ST136 Umbria 29/04/1984 5.6 normal 17 A

6326 2142 ST2496 South Iceland (aftershock) 21/06/2000 6.4 strike slip 14 Amedie: 5.885714286 12.42857143

Combinazione 419

P a g e |22

b)Combination89881(Output>Plot&getrecords>89881)

c)Combination99444(Output>Plot&getrecords>99444)

Figure7.ThefirsttripletfoundbyusingtheoptionDifferent3.

Waveform ID Earthquake ID Station ID Earthquake Name Date MwFault

MechanismEpicentral

Distance [km]EC8 Site

class5655 1825 ST2950 NE of Banja Luka 13/08/1981 5.7 oblique 10 A5655 1825 ST2950 NE of Banja Luka 13/08/1981 5.7 oblique 10 A385 176 ST155 Lazio Abruzzo (aftershock) 11/05/1984 5.5 normal 15 A385 176 ST155 Lazio Abruzzo (aftershock) 11/05/1984 5.5 normal 15 A

6115 2029 ST1320 Kozani 13/05/1995 6.5 normal 17 A4675 1635 ST2487 South Iceland 17/06/2000 6.5 strike slip 13 A6335 2142 ST2557 South Iceland (aftershock) 21/06/2000 6.4 strike slip 15 A

medie: 5.971428571 13.57142857

Combinazione 89881

Waveform ID Earthquake ID Station ID Earthquake Name Date MwFault

MechanismEpicentral

Distance [km]EC8 Site

class6342 2142 ST2556 South Iceland (aftershock) 21/06/2000 6.4 strike slip 20 A6341 2142 ST2497 South Iceland (aftershock) 21/06/2000 6.4 strike slip 20 A6341 2142 ST2497 South Iceland (aftershock) 21/06/2000 6.4 strike slip 20 A670 291 ST238 Umbria Marche (aftershock) 06/10/1997 5.5 normal 20 A766 292 ST266 Umbria Marche (aftershock) 14/10/1997 5.6 normal 12 A382 176 ST140 Lazio Abruzzo (aftershock) 11/05/1984 5.5 normal 16 A242 115 ST225 Valnerina 19/09/1979 5.8 normal 5 A

medie: 5.942857143 16.14285714

Combinazione 99444

P a g e |23

Case2:Cosenza,SLCCase2a:Selectionofasetof7-scaledaccelerogramsaccordingtothehazarddisaggregationintermsofPGAandSa(T=1.0sec).In the following, a set of unscaled accelerograms for Cosenza (Latitude 39.314, Longitude16.215) considering the Collapse Limit State (SLC) of a structure on a type A soil with T1topographiccategory,50yearsnominallifeandFunctionalClassII,isselected.Thefirststepistodefinetheabovementionedparameterstodeterminetheelasticaccelerationresponsespectrum,thatisthetargetspectrum.Forthiscase,disaggregationofPGAandSa(T=1.0sec)withaprobabilityofexceedanceof5%in50yearsarebothshowninFigure84.Therangesofmagnitude[5.5–7]andofdistance[0km–20km]havebeenusedand2x32(soilclassA)accelerogramsfrom16differenteventsintheESDhavebeenfound.

Figure8.DisaggregationofthehazardintermsofPGA(a)andSa(T=1.0sec)(b)forCosenzaforareturnperiodof975years.

Assigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s],the software doesn’t find compatible combinations. By clicking on the Preliminary plotoption(Figure9),itisclearthattheanalysiswon’tgivebackapositiveresponseifthechoicefalls on an unscaled set. The average spectrum of the scaled records seems moreencouraging,henceweprefer this solution.ByclickingonNon-Dimensionaloptionandbychoosing a maximum scale factor equal to 2, the software provides 2 compatiblecombinations,with the same tolerance limits, the first ofwhich is indicated in Figure 10.NotethatREXELonlylimitstheaveragescalefactor,whichmaybelargerthanprescribedforindividualrecords.

4 The structural period should drive selection of appropriate disaggregation; REXEL 3.5 beta has embeddeddisaggregationresultsforspectralaccelerationatT=0s(PGA),T=0.5s,T=1.0s,T=1.5s(forItaliansites).

P a g e |24

Figure9.PreliminaryplotforCosenzaSLC:Case2

Figure10.ThefirstcombinationfoundforCosenza,case2

P a g e |25

Case3:Forlì,SLVCase3a: Selectionofa setof 7-unscaledaccelerogramsbyusing the ItalianAccelerometricArchiveITACA.In the following, a set of unscaled accelerograms for Forlì (Latitude 44.218, Longitude12.054)consideringtheSafeLifeLimitState(SLV),anominallifeof50years,functionaltypeII,topographiccategoryT1andsoiltypeB,accordingtoNIBC,isselected.Thefirststepistodefine the above mentioned parameters to determine the elastic acceleration responsespectrum,thatisthetargetspectrum.Definingarbitrarytherangeofmagnitude[6–7]andofdistance[0km–40km],selectingthe ITACAasdatabase,consideringtherecordingsofanysiteclass,REXELfinds2x30accelerogramsfrom5differentevents.Searchingfor1-componentgroundmotionsets,assigningacompatibilitytolerancebetween10% and 30% in the range of period [0.15s – 2s], the software finds 100000 compatiblecombinations,thefirstofwhichisshowninFigure11.

Figure11.ThefirstscaledcombinationfoundforForlì,Case3aCase3b:Selectionofasetof7-unscaledaccelerogramsforspatialanalysis(3components).In the following, a set of unscaled accelerograms for Forlì (Latitude 44.218, Longitude12.054)consideringthesafelifelimitstate(SLV),anominallifeof50years,functionaltypeII, topographiccategoryT1andsoil typeB,accordingtoNIBC, isselected. In thiscase it issearchedforasetwhichincludesallthreecomponentsofgroundmotion(i.e.,includingtheverticalone).Thefirststepistodefinetheabovementionedparameterstodeterminethehorizontalandverticalelasticaccelerationresponsespectra(Figure12).

P a g e |26

Figure12.DefinitionofthetargetspectrumforForlì,case3Considering intervals of magnitude and distance of respectively [4.5, 6] and [0, 30km]obtained from the disaggregation of seismic hazard in terms of Sa(T=1.0sec) with aprobability of exceedance of 10% in 50 years (Figure 13), selecting ESD as database,consideringonlytherecordingsonBclasssoil(Sameastargetspectrum),REXELfinds3x237accelerograms referred to 149 different events. Because of the large number ofaccelerograms found, the search may take a very long time; moreover, clicking on thePreliminary plot option (Figure 14), it is clear that the analysiswon’t give back a positiveresponse.

Figure13.DisaggregationofthehazardintermsofSa(T=1.0sec)forForlìforareturnperiodof475years.

P a g e |27

Figure14.PreliminaryplotreferringtoM[4.5,6]andR[0,30Km]Increasing the rangeofmagnitude ([6,8])anddecreasing the rangeofdistance ([10,20]),the software finds 3x24 accelerograms from12different events.Assigning a compatibilitytolerance between 10% and 30% in the range of period [0.15s – 2s] for the horizontalcomponent and assigning a compatibility tolerance between 10% e 70% in the range ofperiod[0.15s–1s]fortheverticalcomponent,REXELfinds1005compatiblecombinationsfor the horizontal component, but doesn’t find any compatible set with spectrum-compatible vertical components. At this point the program asks the user if he wants tochange the compatible limits for the vertical component and then theuser candecide todecreasetherangeofperiodsortoincreasethetolerancelimits.It’s possible, for the same scenario of magnitude [6, 8] and distance [10, 20], to chooserecords fromall typeof soil (Any site class) increasing thenumbers of registrations to beprocessed(Figure15).

P a g e |28

Figure15.PreliminaryplotreferringtoM[6,8]andR[10,20Km];AnysiteclassProcessing3x42accelerogramsfrom19events,assigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s]forthehorizontalcomponentandassigningacompatibility tolerancebetween10%e70% in the rangeofperiod [0.15s–1s] for theverticalcomponent,REXELfinds100000combinationsforthehorizontalcomponentand31for the vertical component . The program shows by default the first compatible threedimensional combination found, which is that featuring the ID (referred to horizontalcomponents)number53644(Figure16).

P a g e |29

Figure16.Thefirst3-componentscompatiblecombinationfound(Combinationno.53644)forForlì,case3b.

Waveform ID Earthquake ID Station ID Earthquake Name Date Mw Fault Mechanism Epicentral Distance [km]

EC8 Site class

333 157 ST121 Alkion 24/02/1981 6.6 normal 20 C1313 474 ST1100 Ano Liosia 07/09/1999 6 normal 16 B134 63 ST24 Friuli (aftershock) 15/09/1976 6 thrust 14 B170 81 ST46 Basso Tirreno 15/04/1978 6 oblique 18 C

4673 1635 ST2482 South Iceland 17/06/2000 6.5 strike slip 15 B6277 1635 ST2558 South Iceland 17/06/2000 6.5 strike slip 15 A535 250 ST205 Erzincan 6.6 strike slip 13 B

medie: 6.314286 15.85714286

P a g e |30

Case4:Sant’AngelodeiLombardi,SLVCase 4a: Selection of a set of 7-unscaled accelerograms by usingdisaggregationforSa(T=1.0s).In the following, a set of unscaled accelerograms for Sant’Angelo dei Lombardi (Avellino)(Latitude 40.8931, Longitude 15.1784) considering the Life Safety Limit State (SLV), anominal life of 50 years, functional type II, topographic category T1 and soil type A,accordingtoNIBC,isselected.Thefirststepistodefinetheabovementionedparameterstodetermine the elastic acceleration response spectrum, that is the target spectrum (Figure17).

Figure17.DefinitionofthetargetspectrumforSant’AngelodeiLombardi,case4Starting from the disaggregation of seismic hazard in terms of the Sa(T=1.0sec) with aprobability of exceedance of 10% in 50 years (Figure 18), selecting the ESD as database,considering only the recordings on A class soil (Same as target spectrum) with highmagnitude[6.4-7.2]andlowdistance[5-15km],REXELfinds2x8accelerogramsreferredto3differenteventsintheESDdatabase.ClickingonthePreliminaryplotoption(Figure19),itispossibletoimaginethattheanalysiswillgivebackapositiveresponse.

P a g e |31

Figure18.DisaggregationofthehazardintermsofSa(T=1.0sec)forSant’AngelodeiLombardiforareturnperiodof475years.

Figure19.PreliminaryplotreferringtoM[6.4,7.2]andR[5,15Km];AclasssoilAssigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s]for the horizontal component, REXEL finds, by I’m feeling lucky option, the compatiblecombinationofFigure20.

P a g e |32

Figure20.SetfoundforSan’AngelodeiLombardi,case4

P a g e |33

Case5:Napoli-Ponticelli,SLCCase 5a: Selection of a set of 7-unscaled accelerograms by using seconddisaggregationmodeforSa(T=1.0s).

In the following, a set of unscaled accelerograms for Ponticelli (Napoli) (Latitude 40.8516,Longitude 14.3446) considering the Collapse Limit State (SLC), a nominal life of 100 years,functional type IV, topographiccategoryT1andsoil typeB,accordingtoNIBC, isselected.The first step is to define the above mentioned parameters to determine the elasticaccelerationresponsespectrum,thatisthetargetspectrum(Figure21).

Figure21.DefinitionofthetargetspectrumforPonticelli,case5StartingfromtheseconddisaggregationmodeofseismichazardreferredtotheSa(T=1.0sec)withaprobabilityofexceedanceof2%in50years(Figure22),selectingtheESDasdatabase,considering only the recordings on B class soil (Same as target spectrum) with highmagnitude[6.3-7.6]andmedium-highdistance[15-100km],REXELfinds2x60accelerogramsreferred to 20 different events in the database. Clicking on the Preliminary plot option(Figure23),itispossibletoimaginethattheanalysiswillgivebackapositiveresponse.

P a g e |34

Figure22.DisaggregationofthehazardintermsofSa(T=1.0sec)forPonticelliforareturnperiodof475years.

Figure23.PreliminaryplotreferringtoM[6.4,7.2]andR[5,15Km];AclasssoilAssigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s]for the horizontal component, REXEL finds, by I’m feeling lucky option, the compatiblecombinationofFigure24.

P a g e |35

Figure24.SetfoundforPonticelli,case5a

Case5b:Selectionofasetof7-scaledaccelerogramsbyusing IDconditionalhazard.ConsideringagainthesameexampleinPonticelli,let’sconsiderselectionofhorizontalscaledaccelerogramsaccordingtoconditionalhazard(Iervolinoetal.,2010b) intermsof IDgiventhedesignvalueofPGA(i.e.thevalueofPGAfromcode-basedtargetspectrum).Tothisaim,usingthe[IDconditionalhazard]optionofREXEL,thesoftwarereturnsthecomplementarycumulativedensityfunctionsofIDconditionalonPGAforthesite(Figure25).

Figure25.ProbabilityofexceedanceofIDgivenPGAforPonticelli,case5b

P a g e |36

Specifying the ID intervals to [5, 10], i.e., an intervals chosen on the basis of conditionalhazardintermsofIDwithanexceedanceprobabilitygreaterthan50%givenPGA(Figure25),and selecting the Same as target spectrum option, REXEL founds 105 x 2 components ofmotion record from 94 different earthquakes (ESD database). Assigning, as tolerances fortheaveragespectralmatching,10%lowerand30%upperintheperiodrange0.15s÷2sandselecting the options to stop the search after the first combination is found, REXELimmediatelyreturnsthecombinationofscaledaccelerogramsinFigure26.

Figure26.SetfoundforPonticelli,case5b

Case 5c: Selection of an individual record using PGV as parameter forpreliminarydatabasesearch.Considering again the same example in Ponticelli, let’s consider selection of an individualhorizontalrecordusingPGVasparameterforpreliminarydatabasesearch.SpecifyingthePGVintervalsto[0.3m/s,0.5m/s]andselectingtheSameastargetspectrumoption,REXELfounds4x2componentsofmotionrecordfrom4differentearthquakesfromESD(Figure27a).Assigning,astolerancesfortheaveragespectralmatching,50%lowerand50%upperintheperiodrange0.15s÷2sandselectingtheoptionstostopthesearchafterthefirstrecordisfound,REXELimmediatelyreturnstherecordinFigure27b.

(a)

P a g e |37

(b)

Figure27.Resultsofpreliminaryresearch(a)andrecordfoundforPonticelli(b),case5cCase 5d: Selection of a set of 7-unscaled accelerograms using PGA asparameterforpreliminarydatabasesearch.Considering again the same example in Ponticelli, let’s consider selection of an individualhorizontalrecordusingPGAasparameterforpreliminarydatabasesearch.Specifying the PGA intervals to [0.3g, 0.5g] and selecting the Any site class option (forrecords from ESD), REXEL founds 14 x 2 components ofmotion record from 13 differentearthquakes (Figure 28a). Assigning, as tolerances for the average spectralmatching, 10%lowerand30%upper in theperiodrange0.15s÷2sandselecting theoptions tostop thesearchafterthefirstcombination is found,REXEL immediatelyreturnstheset inFigure28(b).

(a)

(b)

Figure28.Resultsofpreliminaryresearch(a)andrecordsfoundforPonticelli(b),case5d

P a g e |38

Case6:ASCEspectrumandSIMBADdatabaseCaso6a:Selectionofasetof30-scaledaccelerograms.In thefollowing,asetof30-scaledaccelerograms isselectedstarting fromanASCEdesignspectrum with TL, SS and S1 parameters respectively equal to 3, 1.25 and 0.4 (furtherinformationaboutASCEspectracanbefoundinFEMAP-750,2009).ChosensoilclassisBandonlythehorizontalcomponentisconsidered.SelectingSIMBADasdatabase,consideringrecordingsonanysiteclasswithhighmagnitude[6-7] and distance [0-30 km], REXEL finds 2x167 accelerograms referred to 42 differenteventsinthedatabaseasreportedinFigure29.Assigningacompatibilitytolerancebetween10%and30%intherangeofperiod[0.15s–2s]for the horizontal component, REXEL finds, by I’m feeling lucky option, the compatiblecombinationsofFigure30a(1-component)andFigure30b(2-components).

Figure29.Designspectrumdefinitionandresultofpreliminaryresearch,case6.

P a g e |39

(a) (b)

Figure30.Foundscaledsetsof30recordfor1(a)or2(b)horizontalcomponents,case6.

AppendixAEpsilon is defined as the number of standard deviation by which the logarithmic groundmotion departs from the median predicted by the chosen attenuation relationship.Analyticalexpressionisreportedhere:

( ) ( )( )aS

aa SS

log

loglogs

e -= (1)

In Equation (1): aS is the recorded spectral acceleration; ( )aSlog is the mean of thelogarithmsof aS obtainedfromthegroundmotionpredictionequation(GMPE);and ( )aSlogs

isthestandarddeviationofthelogarithmsof aS ,stillfromtheGMPE.UsedGMPE is theoneprovidedbyAmbraseys et al. (1996): itwas fittedon recordswithsurfacemagnitude (Ms) from4.0 to7.5andsource-distanceup to200km.Because thoseintervalsofmagnitudeanddistancearenotuniformlyrepresentedbytherecordsinREXEL,foreachimplementeddatabase(ITACA,ESDandSIMBAD),meanoflogarithmicdifferencesbetweenrecordedgroundmotionandpredictedspectralacceleration(residual)isdifferentfromzero(asshowninFigure31a)andstandarddeviationsofresidualsforeachstructuralperiodaredifferentfromvaluesreportedinAmbraseysetal.(1996)(Figure31b).

Figure31.Average(a)andstandarddeviationofresidualsfromthehorizontalGMPE.

The hypothesis of normal distribution of e values seems satisfied for each database asgraphicallyrepresentedinthefollowingplotsforsomeofthespectralperiodsprovidedbyGMPE.

P a g e |41

Figure32.Distributionsofe valuesforITACA(a),ESD(b)andSIMBAD(c)database.

REFERENCESAmbraseys, N.N., Simpson, K.A., Bommer, J.J. (1996). Prediction of Horizontal ResponseSpectrainEurope,EarthquakeEngineeringandStructuralDynamics25,371-400.

ASCE,AmericanSocietyofCivilEngineering(2006).MinimumDesignLoadsforBuildingsandOtherStructures(7-05),StandardsASCE/SEI7-05.

Bojórquez E., Iervolino I. (2011) Spectral shape proxies and nonlinear structural response,SoilDynamicsandEarthquakeEngineering,31(7),996-1008.

CEN, European Committee For Standardisation (2003). Eurocode 8: Design provisions forearthquake resistance of structures, Part 1.1: general rules, seismic actions and rules forbuildings.Pren1998-1.

Chioccarelli E., Esposito S., Iervolino I. (2012). Implementing conditional hazard forearthquake engineering practice: the Italian example. Proceedings of 15 WCEE, Lisbon,Portugal.

Convertito V., Iervolino I., Herrero A. (2009). The importance of mapping the designearthquake: insights for southern Italy. Bulletin of the Seismological Society of America,99(5),2979–2991.

CosenzaE.,ManfrediG.(2000).DamageIndexandDamageMeasures.ProgressinStructuralEngineeringandMaterials,2(1):50-59.

CS.LL.PP(2008).DM14Gennaio2008:Normetecnicheperlecostruzioni.GazzettaUfficialedellaRepubblicaItaliana,29.

FEMA P-750, NEHRP Recommended Seismic Provisions for New Buildings and OtherStructure, Washington, D.C., 2009.Iervolino I., Chioccarelli E., Convertito V. (2011).Engineeringdesignearthquakesfrommultimodalhazarddisaggregation,SoilDynamicsandEarthquakeEngineering,31(9):1212–1231.

IervolinoI.,GalassoC.,CosenzaE.(2010a).REXEL:computeraidedrecordselectionforcode-basedseismicstructuralanalysis.BulletinofEarthquakeEngineering,8:339-362.

Iervolino I., Giorgio M., Galasso C., Manfredi G. (2010b). Conditional hazard maps forsecondaryintensitymeasures.BulletinoftheSeismologicalSocietyofAmerica,100(6):3312–3319.

Smerzini C., Paolucci R. (2011). SIMBAD: a database with Selected Input Motions fordisplacement-BasedAssessmentandDesign–1strelease.ReportofDPC-ReLUIS2010-2013project(http://wpage.unina.it/iuniervo/SIMBAD_Database_Polimi.pdf).