GEOTECHNICALEARTHQUAKEENGINEERING GEOTECHNICAL, GEOLOGICAL AND EARTHQUAKE ENGINEERING Volume9 SeriesEditor AtillaAnsal,KandilliObservatoryandEarthquakeResearchInstitute, Bog˘azic¸iUniversity,Istanbul,Turkey EditorialAdvisoryBoard JulianBommer,ImperialCollegeLondon,U.K. JonathanD.Bray,UniversityofCalifornia,Berkeley,U.S.A. KyriazisPitilakis,AristotleUniversityofThessaloniki,Greece SusumuYasuda,TokyoDenkiUniversity,Japan Forothertitlespublishedinthisseries,goto www.springer.com/series/6011 Geotechnical Earthquake Engineering Simplified Analyses with Case Studies and Examples by MILUTIN SRBULOV UnitedKingdom withForewordof E.T.R.Dean 123 Dr.MilutinSrbulov UnitedKingdom [email protected] ISBN:978-1-4020-8683-0 e-ISBN:978-1-4020-8684-7 LibraryofCongressControlNumber:2008931592 (cid:2)c 2008SpringerScience+BusinessMediaB.V. Nopartofthisworkmaybereproduced,storedinaretrievalsystem,ortransmitted inanyformorbyanymeans,electronic,mechanical,photocopying,microfilming,recording orotherwise,withoutwrittenpermissionfromthePublisher,withtheexception ofanymaterialsuppliedspecificallyforthepurposeofbeingentered andexecutedonacomputersystem,forexclusiveusebythepurchaserofthework. Printedonacid-freepaper 9 8 7 6 5 4 3 2 1 springer.com Foreword Measurable earthquakes occur very frequently in many parts of the world. For example,Shepherd(1992)lists7283earthquakesrecordedintheCaribbeanAntilles inthe22-yearperiod1964to1985,arateofabout1earthquakeperday.Somewere due to movements of highly stressed rock at more than 100 km below the ground surface(ShepherdandAspinall,1983).Similarhighlevelsofactivityarefoundin allseismicallyactiveregionsoftheworld. Astheearthquakevibrationstravelfromthesourcetowardsthegroundsurface, theenergyspreadsoutandalsodissipates,sothatenergydensityreduceswithdis- tance from source. For the majority of events, shaking has reduced to levels that peoplecannotfeelbythetimeitreachesthegroundsurface.Forsomeevents,suf- ficient energy reaches the surface for people to feel minor effects. For a few, the energyreachingthesurfaceissufficienttocausemajordamage. Since earthquake shaking is transmitted through ground, and since ground also supportsbuildingsandotherstructures,theartandscienceofgeotechnicalengineer- ingisanimportantpartofearthquakeengineering.Avarietyofconceptsandtech- niques are detailed by Kramer (1996), Day (2002), Chen and Scawthorne (2003), andothers.Someoftheimportantgeotechnicalaspectsare: (cid:2) The particle mechanical nature of soil (Mitchell and Soga, 2005; Lambe and (cid:2) Whitman,1979) (cid:2) Terzaghi’sPrincipleofEffectiveStress(Terzaghietal,1996) (cid:2) Linear,isotropicelasticmodels(DavisandSelvadurai,1996) Thetheoryofsoilplasticity(Drucker etal.,1957; Davisand Selvadurai, 2002; (cid:2) Loret,1990) (cid:2) TheMohr-Coulombfailureenvelope(LambeandWhitman,1979;Das,2004) The characterization of soil properties, and theories of compressibility, flow of water through soils, fluidization, and consolidation of soils (Florin and Ivanov, 1961;LambeandWhitman,1979;HeidariandJames,1982;WrothandHoulsby, (cid:2) 1985;Terzaghietal,1996;Das,2004) Criticalstatesoilmechanics,whichseekstoincorporatesoilelasticity,plasticity, strength,density,andconsolidationintoasingleunifyingtheoreticalframework (Schofield and Wroth, 1968; Atkinson and Bransby, 1978; Muir-Wood, 1992; Schofield,2005) v vi Foreword (cid:2) Advancedsiteinvestigationandlaboratorytestingtechniques(Hunt,2005;Head, (cid:2) 2006) Advancedmethodsforslopestabilityassessment(Abramsonetal,1996;Corn- forth,2005),andbearingcapacityandlateralearthpressure(eg.Choudharyetal, (cid:2) 2004;KumarandGhosh,2006) Liquefactionandthesteadystateconcept(Castro,1969;SeedandIdriss,1971; Poulos, 1981; Vaid and Chern, 1985; Seed, 1988; Ishihara, 1995; Jefferies and (cid:2) Been,2006) Shaking table and centrifuge model testing (Schofield, 1980; Arulanandan and (cid:2) Scott,1994;Taylor,1994) Thedevelopingtheoriesofunsaturatedsoilmechanics(FredlundandRahardjo, (cid:2) 1993) Theuseofadvanceconstitutivemodels(Loret,1990;YamamuroandKaliakin, 2005)withfiniteelementmethods(ZienkiewiczandTaylor,1989,1991;Britto (cid:2) andGunn,1987;Finn,1999;Potts,2003) The global gathering, processing, and use of collective experience (Youd and Idriss,2001) Based on these and other factors, advances in understanding have been incor- porated in design codes including the Uniform Building Code (UBC, 1997), the International Building Code (IBC, 2006), Eurocode 8 (2004), API RP2A (2005), ISO19901(2004),andmanyothers. To support these developments, it can be highly desirable to document some simplifiedmodelsthatareeasiertounderstand,retainandexplainthefundamental physics involved, and provide ways of assessing the relevance, reliability, and ap- plicability of more sophisticated approaches. It is also rather useful to be able to identify the most significant publications in a technical literature that is now very extensiveindeed.ThemonographpresentssomeoftheAuthor’sdescriptions,case histories,experiencesandcommentsonavarietyofsimplifiedmodelsforengineer- ing design and analysis. This is valuable both for persons new to the subject who will learn of the wide-ranging considerations involved, and to other experienced practitionerswhowillbeabletocompareexperienceswiththosesharedhere. SeniorLecturerinGeotechnicalEngineering, E.T.R.Dean UniversityoftheWestIndies Preface This monograph contains descriptions of numerous methods aimed at ease and speedofuseformajorproblemsingeotechnicalearthquakeengineering.Comments onassumptions,limitations,andfactorsaffectingtheresultsaregiven.Casestudies and examples are included to illustrate the accuracy and usefulness of simplified methods.Alistofreferencesisprovidedforfurtherconsiderations,ifdesired.Mi- crosoftExcelworkbooksreferredtoinAppendicesandprovidedonanaccompany- ingCDareforthecasestudiesandexamples consideredinthemonograph. Some ofthereasonsforusingthismonographarementionedbelow. Manycodesandstandardscontainrecommendationsonbestpracticebutcompli- ancewiththemdoesnotnecessarilyconferimmunityfromrelevantstatutoryandle- galrequirements(asstatedinBritishStandards).Someseismiccodesandstandards wererevisedaftermajoreventssuchasthe1995Hyogo-kenNambuandthe1994 Northridge earthquakes. Codes contain clauses without references to the original sourcesformoredetailedconsiderationswhencasesthatrequiresuchconsideration appear in practice. Codes do not contain explanations of the statements expressed in them. Codes are brief regarding ground properties and ground response. For example, Eurocode 8 – Part 5 requires assessment of the effects of soil-structure interactionincertaincircumstancesbutdoesnotspecifythedetailsoftheanalyses. Therefore,theuseofcodesandstandardsalonemaynotbesufficientinengineering practice. Inengineeringpractice,thereisoftenratherlittleinteractionbetweenstructural and foundation disciplines. Structural engineers often consider ground in a sim- plified way using equivalent springs. Geotechnical engineers consider often only loading from structures on foundations. Dynamic soil-structure interaction is very complexandanalyzedmainlybyspecialistingeotechnicalearthquakeengineering. Thismonographshouldhelpgeotechnicalandstructuralengineerstocommunicate effectively to better understand solutions of many problems in geotechnical earth- quakeengineering. Specialists in non-linear dynamics analyses need to recognize that the motion of a non-linear system can be chaotic and the outcomes can be unrepeatable and unpredictable. Baker and Gollub (1992), for example, show that two conditions are sufficient to give rise to the possibility of chaotic motion: the system has at least three independent variables, and the variables are coupled by non-linear vii viii Preface relations. Equivalent linear and simplified non-linear dynamic analysis described in this monograph can be used to avoid possible chaotic outcomes of a complex non-lineardynamicanalysis.Groundmotioncausedbyearthquakesischaoticand therefore greater accuracy of sophisticated methods loses its advantage. Expected ground motion can be predicted only approximately, and simplified analyses are fasterandeasiertoolsforparametricstudiescomparedtosophisticatedmethods. UnitedKingdom MilutinSrbulov Acknowledgements ProfessorMaksimovicpersuadedmetoswitchprofessionfromconcretestructures to geotechnics right after my graduation. He pioneered studies of soil mechanics paidbyEnergoprojektCo.atImperialCollegeintheU.K.TheMScsoilmechanics studyin1984/85enabledmetoobtainthepositionofaresearchassistantlater. I was honored and privileged to work with Professor Ambraseys on a number of research projects supported by the Engineering and Physical Science Research CounciloftheUnitedKingdomandbytheEPOCHprogramoftheCommunityof European Countries at Imperial College in London during the period 1991–1997. Thesimplifiedapproachusedinourresearchisdirectlyapplicabletoroutineengi- neeringpractice. Dr E.T.R. Dean reviewed several of my papers and was of great help with his detailed and precise comments for the improvement of the initial versions of the papers. He kindly reviewed the monograph and made a significant contribution towardstheimprovementoftheclarityandreadabilityofthetext. Elsevier publishers kindly granted permission to reproduce Fig. 5B, Fig. 10, Fig. 11, 2/3 of Discussion, and Appendix A of the paper by Ambraseys and Sr- bulov (1995) in print and electronic format in all languages and editions. Elsevier publisherskindlygrantedpermissiontoreproducepages255to268ofthepaperby Srbulov(2001)inprintandEnglishversion. Patron Editore publishers kindly granted permission to reproduce parts of my paperspublishedinthejournalEuropeanEarthquakeEngineering. TheAmericanSocietyofCivilEngineerskindlygrantedpermissiontoreproduce inprintandelectronicversionTable2fromZhangetal.(2005)paper. ix