Thefrequency-dependentelementsinthecodeSASSI:Abridgebetweencivilengineersandthesoil–structureinteractionspecialistsOriginalResearchArticle

Afterfourdecadesoftheintensivestudiesofthesoil-structureinteraction(SSI)effectsinthefieldoftheNPPseismicanalysisthereisacertaingapbetweentheSSIspecialistsandcivilengineers.TheresultsobtainedusingtheadvancedSSIcodeslikeSASSIareoftenratherfarfromtheresultsobtainedusinggeneralcodes(thoughmatchtheexperimentalandfielddata).Thereasonsforthediscrepanciesarenotclearbecausenoneofthepartiescanrecalltheresultsofthe“otherparty”andinvestigatetheinfluenceofvariousfactorscausingthedifferencestepbystep.Asaresult,civilengineersneitherfeeltheSSIeffects,norcontrolthem.TheauthorbelievesthattheSSIspecialistsshoulddothefirststepforward(a)recalling“viscous”dampinginthestructuresversusthe“material”oneand(b)convolutingalltheSSIwaveeffectsintotheformatof“soilspringsanddashpots”,moreorlessclearforcivilengineers.Thetoolforbothtaskscouldbeaspecialfiniteelementwithfrequency-dependentstiffnessdevelopedbytheauthorforthecodeSASSI.ThiselementcanrepresentbothsoilandstructureintheSSImodelandhelptosplitvariousfactorsinfluencingseismicresponse.Inthepaperthetheoryandsomepracticalissuesconcerningthenewelementarepresented.