简介：Thispaperpresentsastep-by-stepprocedureusingthethree-dimensionalboundaryelementapproachtostudythebehaviorofsemi-circularcanyonsunderseismicshearwaves.TheboundaryelementcodeTDASCallowsutilizationforvariouscanyongeometries,evaluationofconcurrentseismicwavesandcalculationofthegroundmotionsoncanyonsduetoanexcitationatanyarbitrarypointoftheincidentfield.Consideringthewideningratioofthecanyon(includingprismatic,semi-prismaticandnon-prismaticcanyons),wavecharacteristics(wavelength,dimensionlessperiod,direction)andmaximumamplificationpattern,thesolutionwasappliedtocarryoutaseriesofparametricstudies.Itwasshownthatcanyonformcansignificantlyaffectthedisplacementamplification,especiallyatthepointslocatedonitsedges.Byincreasingthewavedimensionlessfrequency(η>1),theamplificationpatternbecomesmorecomplex.Onthebasisoftheresultsfromavarietyofconsideredcases,anewexpressionhasbeenpresentedforthelimitingwavelengthbeyondwhichthewideningofthecanyonwillnothaveamajoreffectonthedisplacementamplification.Toverifythereliabilityoftheproposedapproach,theobtainedresults,expressedintermsofdisplacementamplitude,werecomparedwiththosefromtheavailablepublishedliteratureandareasonablygoodagreementwasobserved.

简介：Earthquakeengineershavemadealotofeffortstoderiveacomprehensivesetofclosedformexpressionsforperformanceevaluationofframes,whicharealreadypresentedinguidelinessuchasSAC/FEMA.Theseanalyticalexpressionshavebeendevelopedtoestimatetheannualprobabilityofexceedingalimitstate.Intheprocessofsuchseismicassessments,someessentialassumptionsareadoptedtosimplifytheprocess.Oneofthesefundamentalassumptionsdeclaresthatdriftdemandatanyseismicintensitylevelfollowsalognormaldistributionarounditsmedian.Toinvestigatethevalidityofthisassumption,thispaperdescribesacasestudyofthetypesoferrorsthatcouldbeproducedbyusingthesamplemedianasthecentraltendency.BasedontheMaximumLikelihoodEstimationmethodaswellasotherstatisticalevidence,thispaperproposestheuseofthesamplegeometricmeaninsteadofthesamplemedianforthecentraltendency.Further,theresultsofseismicreliabilityevaluationsof4sampleframesarecomparedbasedonutilizingboththegeometricmeanandthesamplemedian.Inthisprocess,bothfirstandsecondorderpowerlawfitsofthehazardcurveareimplementedtocomparetheeffectsofhazardestimationandtheselectionofthecentraltendencyonthefinalresults.Itisobservedintheapplicationexamplethatthesamplegeometricmeancouldleadtomoreaccurateresults.