FINITE ELEMENT ANALYSIS AND DESIGN OF STEEL AND STEEL–CONCRETE COMPOSITE BRIDGES FINITE ELEMENT ANALYSIS AND DESIGN OF STEEL AND STEEL–CONCRETE COMPOSITE BRIDGES by EHAB ELLOBODY Professor,Department of Structural Engineering, Facultyof Engineering, Tanta University, Egypt AMSTERDAM (cid:129) BOSTON (cid:129) HEIDELBERG (cid:129) LONDON NEW YORK (cid:129) OXFORD (cid:129) PARIS (cid:129) SAN DIEGO SAN FRANCISCO (cid:129) SINGAPORE (cid:129) SYDNEY (cid:129) TOKYO Butterworth-Heinemann is an imprint of Elsevier Butterworth-HeinemannisanimprintofElsevier 225,WymanStreet,Waltham,MA01803,USA TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK Firstedition2014 Copyright©2014ElsevierInc.Allrightsreserved Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmittedin anyformorbyanymeanselectronic,mechanical,photocopying,recordingorotherwise withoutthepriorwrittenpermissionofthepublisher. 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ISBN978-0-12-417247-0 1.Ironandsteelbridges–Designandconstruction.2.Concretebridges–Designand construction.3.Finiteelementmethod.I.Title. TG380.E452015 624.205–dc23 2014011942 BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ForinformationonallButterworth-Heinemannpublications visitourwebsiteatstore.elsevier.com PrintedandboundinUSA 14 15 16 17 18 10 9 8 7 6 5 4 3 2 1 ISBN:978-0-12-417247-0 11 CHAPTER Introduction 1.1 GENERAL REMARKS Steel andsteel-concretecompositebridgesarecommonlyused alloverthe world, owing to the fact that they combine both magnificent aesthetic appearance and efficient structural competence. Their construction in a country not only resembles the vision and inspiration of their architects butalsorepresentsthecountry’sexistingdevelopmentanddreamofabetter future. Compared to traditional reinforced concrete (RC) bridges, steel bridges offer many advantages, comprising high strength-to-self weight ratio,speedofconstruction,flexibilityofconstruction,flexibilitytomodify, repairandrecycle,durability,andartisticappearance.Thehighstrength-to- selfweightratioofsteelbridgesminimizesdeadloadsofthebridges,whichis particularlybeneficialinpoorgroundconditions.Also,thehighstrength-to- selfweightratioofsteelbridgesmakesiteasytotransport,handle,anderect the bridge components. In addition, it facilitates very shallow construction depths,whichovercomeproblemswithheadroomandfloodclearances,and minimizesthelengthofapproachramps.Furthermore,highstrength-to-self weightratioofsteelbridgespermitstheerectionoflargecomponents,andin special circumstances, complete bridges may be installed in quite short periods. The speed of construction of steel bridges is attributed to the fact that most of the bridge components can be prefabricated and transported to the construction field, which reduces working time in hostile environ- ments.Thespeedofconstructionofsteelbridgesalsoreducesthedurations of road closures, which minimizes disruption around the area of construc- tion. Flexibility of construction of steel bridges is attributed to the fact that the bridges can be constructed and installed using different methods and techniques. Installation may be conducted by cranes, launching, slide-in techniques, or transporters. Steel bridges give contractors the flex- ibilityintermsoferectionsequenceandprogram.Thebridgecomponents canbesizedtosuitaccessrestrictionsatthesite,andonceerected,thesteel girdersprovideaplatformforsubsequentoperations.Flexibilitytomodify, repair,andrecyclesteelbridgesisaresultoftheabilitytomodifythecurrent status of the bridges such as widening the bridges to accommodate more lanesoftraffic.Also,steelbridgescanberepairedorstrengthenedbyadding FiniteElementAnalysisandDesignofSteel Copyright©2014ElsevierInc. andSteel–ConcreteCompositeBridges Allrightsreserved. 1 2 EhabEllobody steel plates or advanced composite laminates to carry more traffic loads. In addition,ifforanyreason,suchasendoftheirlifeofuseorchangeofenvi- ronment around the area, steel bridges can be recycled. Steel bridges are durablebridges,providedthattheyarewelldesigned,properlymaintained, andcarefullyprotectedagainstcorrosion.Finally,steelbridgescanfitmostof the complex architecture designs, which in some cases are impossible to accommodate using traditional RC bridges. HighwaybridgesmadeofRCslabsontopofthesteelbeamscanbeeffi- cientlydesignedascompositebridgestogetthemostbenefitfromboththe steelbeamsandconcreteslabs.Steel-concretecompositebridgesofferaddi- tional advantages to the aforementioned advantages of steel bridges. Com- pared to steel bridges, composite bridges provide higher strength, higher stiffness, higher ductility, higher resistance to seismic loadings, full usage of materials, and particularly higher fire resistance. However, these advan- tages are maintained, provided that the steel beams and concrete slabs are connected via shear connectors to transmit shear forces at the interface between the two components. This will ensure that the two components acttogetherinresistingappliedtrafficloadsonthebridges,whichwillresult insignificant increasesintheallowablevehicularweightlimitations,ability totransportheavyindustrialandconstructionequipment,andpossibilityto issue overload permits for specialized overweight and oversized vehicles. Oneofthemainadvantagesofhavingsteelbeamsactingtogetherwithcon- creteslabsincompositebridgesisthatprematurepossiblefailuresofthetwo separatecomponentsareeliminated.Forexample,oneoftheprimarymodes offailureforconcretebridgesiscrackingoftheconcreteslabsandbeamsin tension,whileforthesteelbridges,thepossiblemodesoffailurearethefor- mationofplastichingesandthebucklingofwebsorflanges.Byhavingthe steel beams work together with the concrete slab, the whole slab will be mainlysubjectedtocompressiveforces,whichreducesthepossibilityoften- silecracking.Ontheotherhand,thepresenceoftheconcreteslabontopof thesteelbeamseliminatesthebucklingofthetopflangeofthesteelbeams. Efficientdesignofsteel-concretecompositebridgescanensurethatboththe steelbeamsandconcreteslabsworktogetherinresistingappliedtrafficloads untilfailureoccursinbothcomponents,preferablyatthesametime,toget the maximum benefit from both components. Numerous books were found in the literature highlighting different aspects of design for steel and steel-concrete composite bridges; for exam- ples, see [1.1–1.11]. The books highlighted the problems associated with the planning, design, inspection, construction, and maintenance of steel Introduction 3 andsteel-concretecompositebridges.Overall,thebooksdiscussedthebasic concepts and design approaches of the bridges, design loads on the bridges fromeithernaturalortraffic-inducedforces,anddesignofdifferentcompo- nentsofthebridges.Ontheotherhand,numerousfiniteelementbooksare foundintheliterature;for examples,see[1.12–1.18],explainingfiniteele- mentmethodasawidelyusednumericaltechniqueforsolvingproblemsin engineeringandmathematicalphysics.Thebooks[1.12–1.18]werewritten to provide basic learning tools for students mainly in civil and mechanical engineering classes. The books [1.12–1.18] highlighted the general princi- ples of finite element method and the application of this method to solve practicalproblems.However,limitedinvestigations,withexamplesdetailed in [1.19, 1.20], are found in the literature in which researchers used finite elementmethodinanalyzingcasestudiesrelatedtosteelandsteel-concrete composite bridges. Recently, with continuing developments of computers andsolvingandmodelingtechniques,researchersstartedtodetailtheuseof finiteelementmethodtoanalyzesteelandsteel-concretecompositebridges, with examples presented in [1.21, 1.22]. Also, extensive experimental and numerical research papers were found in the literature highlighting finite element analysis of steel and steel-concrete composite bridges, which will bedetailedinSection1.3.However,up-to-date,therearenodetailedbooks foundintheliteratureaddressingbothfiniteelementanalysisanddesignof steel and steel-concrete composite bridges, which is credited to this book. The current book will present, for the first time, explanation of the latest finite element modeling approaches specifically as a complete piece work onsteelandsteel-concretecompositebridges.Thisfiniteelementmodeling of the bridges will be accompanied by design examples for steel and steel- concrete composite bridges calculated using current codes of practice. There are many problems and issues associated with finite element modelingofsteelandsteel-concretecompositebridgesintheliteraturethat students,researchers,designers,practitioners,andacademicsneedtoaddress. Incorporating nonlinear material properties of the bridge components in finite element analyses has expanded tremendously over the last decades. In addition, computing techniques are now widely available to manipulate complicatedanalysesinvolvingmaterialnonlinearitiesofthebridgecompo- nents.Thisbookwillhighlightthelatesttechniquesofmodelingnonlinear materialpropertiesofthebridgecomponents.Also,simplifiedanalyticsolu- tionswerederivedtopredictthedistributionofforcesandstressesindiffer- ent bridge components based on many assumptions and limitations. However, accurate analyses require knowledge of the actual distribution 4 EhabEllobody offorcesandstressesinthecomponentmembers,whichisthetargetofthe nonlinear finite element modeling approach detailed in this book. In addi- tion, in case of steel-concrete composite bridges, if the slab cracks under heavytrafficloadsorthesteelbeamyieldsorbuckles,itbecomesextremely important to know the location of failure, the postfailure strength of the component that hasfailed, andthemanner inwhich theforces andstresses will redistribute themselves owing to the failure. Once again, traditional simplifiedanalysescannotaccountforthesecomplexfailuremodesbecause nointeractionbetweenbridgecomponentswasconsidered.Thefiniteele- mentmodelingapproachaimedinthisbookwillcaptureallpossiblefailure modes associated with steel-concrete composite bridges. It should also be notedthatwhilesimplifieddesignmethodshavebeendevelopedtopredict the ultimate capacity of steel bridges or their components, none of these methods adequately predicts the structural response of the bridge in the regionbetweendesignloadlevelsandultimatecapacityloadlevels.There- fore, the proposed finite element modeling approach will reliably predict both the elastic and inelastic responses of a bridge superstructure as well asthestructuralresponseintheregionbetweenthedesignlimitandtheulti- matecapacity.Anothercomplexissueistheslipatthesteel-concreteinter- face in composite bridges that occurs owing to the deformation of shear connectorsunderheavytrafficloads.Thisparameteralsocannotbeconsid- ered using simplified design methods and can be accurately incorporated usingfiniteelementmodeling.Theaforementionedissuesareonlyexamples of the problems associated with modeling of steel and steel-concrete com- positebridges.Overall,thisbookprovidesacollectivematerial,forthefirst time, for the use of finite element method in understanding the actual behaviorandcorrectstructuralperformanceofsteelandsteel-concretecom- posite bridges. Full-scale tests on steel and steel-concrete composite bridges are quite costlyandtime-consuming,whichresultedinascarceintestdatafordiffer- enttypesofbridges.Thedearthinthetestdataisalsoattributedtothecon- tinuing developments, over the last decades, in the cross sections of the bridgesandtheircomponents,materialstrengthsofthebridgecomponents, andappliedloadsonthebridges.Therefore,designrulesspecifiedincurrent codes of practice for steel and steel-concrete composite bridges are mainly based on small-scale tests on the bridges and full-scale tests on the bridge components. In addition, design rules specified in the American Specifica- tions [1.23–1.25], British Standards [1.26], and Eurocode [1.27, 1.28] are based on many assumptions, limitations, and empirical equations. An Introduction 5 exampleoftheshortcomingsincurrentcodesofpracticeforsteel-concrete composite bridges is that, up-to-date, there are no design provisions to considertheactualload-slipcharacteristiccurveoftheshearconnectorsused inthebridges,whichresultsinpartialdegreeofcompositeactionbehavior. This book will detail, for the first time, how to consider the correct and actual slip occurring at the steel-concrete interface in composite bridges throughfiniteelementmodeling.Thisbookwillhighlightthelatestnumer- ical investigations performed in the literature to generate more data, fill in thegaps,andcompensatethelackofdataforsteelandsteel-concretecom- positebridges.Thisbookalsohighlightstheuseoffiniteelementmodeling to improve and propose more accurate design guides for steel and steel- concretecompositebridges,whicharerarelyfoundintheliterature.Inaddi- tion, this book contains examples for finite element models developed for differentsteelandsteel-concretecompositebridgesaswellasworkeddesign examples for thebridges.The authorhopesthat thisbookwillprovidethe necessarymaterialsforallinterestedresearchersinthefieldofsteelandsteel- concrete composite bridges. Furthermore, the book can also act as a useful teaching tool and help beginners in the field of finite element analysis and designofsteelandsteel-concretecompositebridges.Thebookcanprovide arobustapproachforfiniteelementanalysisofsteelandsteel-concretecom- posite bridges that can be understood by undergraduate and postgraduate students. The book consists of seven well-designed chapters covering necessary topicsrelatedtofiniteelementanalysisanddesignofsteelandsteel-concrete compositebridges.Thischapterprovidesageneralbackgroundforthetypes ofsteelandsteel-compositebridgeandexplainstheclassificationofbridges. The chapter also presents a brief review for the components of the bridges andhowtheloadsaretransmittedbythebridgetotheground.Thechapter alsogivesanup-to-datereviewforthelatestavailableinvestigationscarried out on steel and steel-concrete composite bridges. The chapter focuses on mainissuesandproblemsassociatedwiththebridgesandhowtheyarehan- dledintheliterature.Thechapteralsointroducestheroleoffiniteelement modeling to provide a better understanding of the behavior of bridges. Finally, this chapter highlights the main current codes of practice used for designing steel and steel-concrete composite bridges. Chapter2focusesonthenonlinearmaterialbehaviorofthemaincom- ponentsofsteelandsteel-concretecompositebridgescomprisingsteel,con- crete, reinforcement bars, shear connectors, etc. The chapter presents the stress-straincurvesofthedifferentmaterialsusedinthebridgesanddefines 6 EhabEllobody theimportantparametersthatmustbemeasuredexperimentallyandincor- poratedinthefiniteelementmodeling.Thedefinitionsofyieldstresses,ulti- mate stresses, maximum strains at failure, initial stiffness, and proportional limit stresses are presented in the chapter. The chapter enables beginners tounderstandthefundamentalbehaviorofthematerialsinordertocorrectly insert them in the finite element analyses. Covering the behavior of shear connectors in this chapter is important to understand how the shear forces aretransmittedatthesteel-concreteslabinterfacesincompositebridges.In addition,thechapterpresentshowthedifferentmaterialsaretreatedincur- rent codes of practice. Chapter3 presentsthedifferent loads actingon steel andsteel-concrete composite bridges and the stability of the bridges when subjected to these loads. The chapter starts by showing the dead loads of steel and steel- concretecompositebridgesthatareinitiallyestimatedforthedesignofbrid- ges.Then,thechaptermovestoexplainhowtheliveloadsfromtrafficwere calculated.Afterthat, thechapterpresentsthecalculationofwindloads on the bridges and highlights different other loads that may act on the bridges such as centrifugal forces, seismic loading, and temperature effects. When highlightingtheloadsinthischapter,itisaimedtoexplainbothoftheloads acting on railway and highway bridges. The calculations of the loads are based on the standard loads specified in current codes of practice. In addi- tion, the chapter also presents, as examples, the main issues related to the stabilityofsteelandsteel-concretecompositeplategirderandtrussbridges, whichenablereaderstounderstandthestabilityofanyothertypeofbridges. Chapter 4 presents detailed design examples of the components of steel and steel-concrete composite bridges. The design examples are calculated based on current codes of practice. The design examples are shown for thestringers(longitudinalbeamsofthebridges),crossgirders,plategirders, trusses,bracingsystems,bearings,andothersecondarymembersofthebrid- ges.Also,designexamplesarepresentedforsteel-concretecompositebrid- ges.Itshouldbenotedthattheaimofthisbookistoprovideallthenecessary informationandbackgroundrelatedtothedesignofdifferentbridgesusing different codes of practice. Therefore, the design examples presented are hand calculations performed by the author. The chapter explains how the crosssectionsareinitiallyassumed,howthestrainingactionsarecalculated, and how the stresses are checked and assessed against current codes of practice. Chapter 5 focuses on finite element analysis of steel and steel-concrete composite bridges. The chapter presents the more commonly used finite Introduction 7 elementsinbridgesandthechoiceofcorrectfiniteelementtypesandmesh size that can accurately simulate the complicated behavior of the different components of steel and steel-concrete composite bridges. The chapter highlights the linear and nonlinear analyses required to study the stability of the bridges and bridge components. Also, the chapter details how the nonlinear material behavior can be efficiently modeled and incorporated in the finite element analyses. In addition, Chapter 5 details modeling of shear connection for steel-concrete composite bridges. Furthermore, the chapter presents the application of different loads and boundary conditions on the bridges. The chapter focuses on the finite element modeling using any software or finite element package, for example, in this book, the use of ABAQUS [1.29] software in finite element modeling. Chapters 6 and 7 present illustrative examples of finite element models developed to understand the structural behavior of steel and steel-concrete compositebridges,respectively.Thechaptersstartwithabriefintroduction ofthepresentedexamplesaswellasadetailedreviewofpreviousinvestiga- tionsrelatedtothepresentedexamples.Thechaptersdetailhowthemodels weredevelopedandtheresultsobtained.Thepresentedexamplesshowthe effectiveness of finite element models in providing detailed data that com- plementexperimentaldatainthefield.Theresultsarediscussedtoshowthe significanceofthefiniteelementmodelsinpredictingthestructuralresponse of the different bridges investigated. Overall, they aim to show that finite elementanalysisnotonlycanassesstheaccuracyofthedesignrulesspecified incurrentcodesofpracticebutalsocanimproveandproposemoreaccurate design rules. Once again, it should be noted that in order to cover all the latestinformationregardingthefiniteelementmodelingofdifferentbridges, thepresentedfiniteelementmodelsaredevelopedbytheauthoraswellasby other researchers and previously reported in the literature. 1.2 TYPES OF STEEL AND STEEL-CONCRETE COMPOSITE BRIDGES Steel bridges can be classified according to the type of traffic carried to mainly highway (roadway) bridges, which carry cars, trucks, motorbikes, etc. with an example shown in Figure 1.1; railway bridges, which carry trains,withanexampleshowninFigure1.2;orcombinedhighway-railwaybrid- ges, which carry combinations of the aforementioned traffic as shown in Figure1.3.Therearealsosteelbridgescarryingpipelines(Figure1.4),cranes (Figure 1.5), and pedestrian bridges (Figure 1.6), which are also secondary