Principles of reinforced concrete PDF
Preview Principles of reinforced concrete
Principles of Reinforced Concrete Zhenhai Guo AMSTERDAM(cid:129)BOSTON(cid:129)HEIDELBERG(cid:129)LONDON NEWYORK(cid:129)OXFORD(cid:129)PARIS(cid:129)SANDIEGO SANFRANCISCO(cid:129)SINGAPORE(cid:129)SYDNEY(cid:129)TOKYO Butterworth-HeinemannisanimprintofElsevier Butterworth-HeinemannisanimprintofElsevier TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK 225WymanStreet,Waltham,MA02451,USA Firstedition2014 Copyright(cid:1)2014TsinghuaUniversityPress.PublishedbyElsevierInc.Allrightsreserved. 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Becauseofrapidadvancesinthemedicalsciences,inparticular,independentverificationof diagnosesanddrugdosagesshouldbemade BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailabefromtheLibraryofCongress ISBN–13:978-0-12-800859-1 ForinformationonallButterworth-Heinemannpublications visitourwebsiteatstore.elsevier.com PrintedandboundintheUS 1415161718 10987654321 Preface The courses “Theory of Reinforced Concrete Structures” [1-1] and “Strength and Constitutive Relation of Concrete” [1-2] were started in early 1980’s for the post- graduatestudentsinstructuralengineeringandrelatedfieldsinTsinghuaUniversity. The lectures, and the syllabus and contents of both courses are varied during the teachingpractice.Twocoursesarecomposedandnamed“PrinciplesofReinforced Concrete”in1990’s.Theauthorgavealectureonthiscourseforseveralyearsand wrote the textbook ofsame name [1-3], based on the teaching draft. Afterthebookwaspublishedin1999,itisalsoadoptedasthetextbookormain referenceforsimilarcoursesofbothpost-andunder-graduatesofmanyuniversities in China. And, it is helpful as well for the university lecturers. In addition, some- timesthebookisusedbythestructuralengineersduringtheirscientificortechnical work. In 2001, Education Committee of Beijing decided to establish “the elite text- books for university education of Beijing’, and the textbook was selected after appraisement. The new textbook is renamed as “Principle and Analysis of Rein- forced Concrete” [1-4] and published in 2003. The new textbook or the second edition contains most contents of the original one, but some chapters and sections are reformed and two new chapters, i.e. general analysis method of structural memberanddurability,areadded.Inaddition,theexercisesareattachedtoitstext. This book is the English version of textbook “Principle and Analysis of Reinforced Concrete” (in Chinese), but some contents are modified and slightly abridged to reduce its length. There are four parts including twenty chapters in this book. InPartOne,thestrengthanddeformationbehavioranditsvariationregularityof concreteareintroducedindetail,basedonitsbasiccharacteristicandfailuremech- anism. The main mechanical behaviors of various structural concrete, i.e. high- strength,light-weight,andfiberconcrete,arepresentedaswell.And,themulti-axial strengthand constitutiverelation of concreteare brieflycontained. The combination function of reinforcement and concrete is a special problem with importance, when reinforced concrete is considered as a composed structural materialandisdistinguishedfromasinglestructuralmaterial.So,bondanddefor- mation deference between reinforcement and concrete, and confined concrete are discussed inPart Two. In Part Three, the strength,crack, and deformation of flexuraland compressive members, and shear- and torsion-resistances of structural members of reinforced concrete are introduced in detail based on the corresponding experiments. And, the general regularities, working mechanisms, and analysis methods of them are concluded. A reinforced concrete structure may experience some extreme circumstances during its long life, e.g. earthquake, explosion, fatigue, high temperature (fire), or long-term damage (durability). So, the special behaviors of reinforcement and XV XVI Preface concretematerials,andthemechanicalresponsesandanalysismethodsofthestruc- tural membersunder these conditions are introduced brieflyin Part Four. “ReinforcedConcreteStructures”orthesimilar[1-5]isacoursefortheunder- graduate students of Structural Engineering in Chinese university. The main objective of it is to help them to conduct the structural design. Therefore, the main contents of the course include: the mechanical behaviors of reinforcement and concrete are briefly introduced, the behavior, calculation method, and require- ment of design and construction of the basic structural members under various internal forces are presented in detail, and the concept and method of structural design and relevant designcodes are introduced and explained. This book is used for the post-graduate students in structural engineering. The maincontentsareresearchandanalysisofthemechanicalbehavioranditsregularity ofreinforcedconcretestructuralmembers,andthemainobjectiveistosolvevarious questions occurred in engineering practice. Therefore, the general regularities of strengthanddeformationofconcreteunderuni-andmulti-axialstresses,evenunder severalextremecircumstances,areintroducedsystematically,asthisisthebasisfor understandingandanalyzingthestructuralmembers.Whenthemechanicalbehavior ofthestructuralmembersundervariousconditionsarediscussed,theresultsofcor- respondingexperimentalinvestigationsareemphasized,thestressanddeformation states,crackingandfailureprocess,andinfluencesofimportantfactorsareanalyzed indetail,andtheworkingmechanism,theprincipleandmethodofcalculation,and thedeterminationsofthetechnicalindicesareconcluded.Itishopedthatthereader notonlyknowsthegeneralregularitiesofthematerialsandmembersofreinforced concrete,butalsounderstandsthegeneralwayandreasonablemethodforanalyzing and solving the practical problems in reinforced concrete structural engineering, after readingthis book. Whenthisbookissenttopress,theauthorsincerelythankstheprofessorsofelder generation,whoworkedintheDepartmentofCivilEngineering,TsinghuaUniver- sity. They worked and studied seriously and their teaching experiences [1-5][1-6] and research achievements in reinforced concrete structure field enrich my knowl- edge,whichpartlycomposesthebasisofthisbook.Mycolleagues,includingtech- nicians and workers, and post- and under-graduate students, who worked together withintheprocessesofexperimentalandtheoreticalresearcheswithinmanyyears, are appreciated as well. Their cooperation with effort helps to bring about the research achievement, which substantiate and improve the contents of this book. In addition my special thanks is due to my wife, retired professor Suying Qian, who not only patiently typed and input the entire manuscript of this book to form the original computer text, but also takes care thoughtfully of my life. Of course, theprintandpublicationofthisbookisreliedontheeffortsofTsinghuaUniversity Press,itisalsoappreciated. Zhenhai Guo September2013 CHAPTER 1 Introduction CHAPTER OUTLINE 1.1 Developmentandfeaturesofreinforcedconcretestructure.....................................1 1.2 Characteristicsofthiscourse...............................................................................4 1.1 Development and features of reinforced concrete structure Since the first product of reinforced concretewas manufactured and used in struc- tural engineering, only about one hundred years have passed. Compared with soil and timber structure, which is the earliest on earth, used by the original mankind, themasonrystructureofstoneorbrickappearedintheearlysocietyofancientciv- ilizations,andsteelandothermetalstructuresdevelopedafterthe IndustrialRevo- lution,reinforcedconcretestructureistheyoungestoneamongthestructurefamily. However,theperformanceandmanufacturetechniqueofreinforcedconcretestruc- ture are continuously improving and being enhanced, structural configuration and construction get morevariety, and the application scope is widely expanded. Now, reinforced concrete structure is the most prosperous one in structural engineering inmanycountries, especially inChina. Now, the engineering fields using widely reinforced concrete structure are as follows. Buildingengineeringe variouscivil andpublicbuildings, single- andmulti- storeyindustrialbuildings, high-rise andlong-span buildings. Bridge and communication engineering e slab, beam, arch, and truss upper structures,abutments,piers,andfoundations,slopeprotection,retainingwalls, highway pavements, railway sleepers . Hydraulic and harborengineering e dams, hydropower stations, coasts and docks, offshore platforms,ponds and pipelines, aqueducts . Undergroundengineering e tunnels, railways, mines, caissons,piles, foun- dations ofheavyequipment,military defenseworks. Specialengineering e television towers,transmission poles,viaducts, silos, chimneys, pavements andparking apronsof airports ..Evenreinforced con- crete structuresenterinto the machinebuildingfield, e.g. reactor vesselsand 1 PrinciplesofReinforcedConcrete.http://dx.doi.org/10.1016/B978-0-12-800859-1.00001-3 Copyright©2014TsinghuaUniveristyPress.PublishedbyElsevierInc.Allrightsreserved. 2 CHAPTER 1 Introduction containment of nuclear power plants, hydraulicpresses, shipbuilding,lathes, etc., which are occupied traditionallyonly by steel structures. Theinherentcertaintyofacombinationofreinforcementandconcreteisdueto themutualcompensationofthebehaviorofbothmaterialsandtheadvantageofeach materialisfullyutilized.Concreteisthemainbodyofthestructuralmaterialandhas someadvantages,e.g.easymanufacturing,utilizinglocalmaterials,lowinvestment. However,concretehaslowertensilestrengthandisfragileandcrackseasily.There- fore,onlywhenthereinforcementofapropertypeandquantityisputintothecon- crete,thestrengthandductilityofthereinforcedconcretestructureisimprovedand enhancedtosatisfythenecessarysafetyandserviceconditions.Inthemeantime,the disadvantagesofreinforcement,e.g.poorenvironmentalstability,andcorrosionand fireresistance,willbeovercomewhenitisburiedintoconcrete.So,reinforcement andconcretecaneffectivelybecomposedofastructuralmaterialwithhighstrength, good integrity,corrosion andfire resistances,and flexibleuses. Inaddition,concreteisashapelesssubstanceandcanbemadeintoanystructure ofcomplicatedshapeanddifferentsizes,whenapropermoldismanufacturedand installed.Therearesomanydifferentreinforcedconcretestructureswhichinclude notonlytheone-dimensionalmembers,e.g.beam,slab,column,ofsolidandhollow sections of different shapes, but also the two-dimensional members, e.g. flat plate, slab, wall panel, shear-wall,folded plates, and the three-dimensional,e.g. thin and thick shells andirregularsolid, structures. Reinforcedconcreteitselfiscomposedoftwomaterialsandcanalsobeusedasa kindofstructuralmaterialandcombinedwithotherstructuralmaterialstocompose various composite structures, such as reinforced concrete-steel and reinforced concrete-masonry structures. Then, more varieties of structure scheme are devel- opedand the adaptability and applicationscope ofit are expanded. As reinforced concrete structure is widely used in engineering practice, the requirementofproductionacceleratestheresearchworkinallaspects.Theplentiful researchresultsonstructuralschemeandconfiguration,kindandqualityofmaterial, constructiontechnique,mechanicalbehaviorofstructuralmembers,designconcept andcalculationmethod,constructionmeasures,etc.,areachievedandgreatprogress is made asbelow. Some disadvantages of concrete material, such as higher dead weight, lower crackingresistance,strengthincreasingslowly,andseasonallimitationofconstruc- tion,havebeenimprovedorovercome,whenthetechnicalmeasures,whichinclude selectionofrawmaterials,mixandcuretechnique,constructionmanagement,rein- forcement construction, prestressing, and improvement of calculation method, are utilized. In order to enhance the performance of concrete and to reduce its self weight, high-strength (>C50), light-weight (g ¼ 500e1900 kg/m3), fiber, and high- performanceconcretesofvariouscategoriesaredevelopedsuccessivelyandapplied inengineering practice. Whenvariouschemicaladditivesaremixedintoconcreteduringitsmixing,the higher workability, freezing resistance, high strength, and earlier coagulating of 1.1 Development and features of reinforced concrete structure 3 concrete are achieved, even heat-resisting and acid-resisting concrete can be ob- tained. And, pumping, spraying, and self-compacting concrete may be used to improve the manufacturing technique. All kinds of these concretes are suited to different construction andapplication conditionsof reinforced concrete structures. Thestrengthofthesteelreinforcementusedforreinforcedconcretestructureis gradually increased from low value into medium and high values. The steel rein- forcements of low relaxation and with anticorrosion coating are used frequently. Variousresinsandcarbonicfiberbars(orsheets)ofhighstrengthandanticorrosion are alsoused successfullynowtoreplace the steel reinforcement. The behaviorof concrete under uni- and multi-axial stress states and itsfailure criterion and constitutive relation have been investigated experimentally and theo- retically, and great progress has been made. The strength and deformation of con- crete under various conditions, e.g. repeated load, high-speed loading, sustained load,at elevatedtemperature, are also tested and manyresultsare reported. The bond behavior between reinforcement and concrete, including working mechanism,characteristicvaluesofbondstrengthandslip,shapeandcalculation modelofs-scure,havebeeninvestigatedformanyyears.Theanchorageofrein- forcement is important in engineering practice and an effective measure is avail- able now. The mechanical behaviors of various structural members under static and dy- namic loads are always the key topics of research on reinforced concrete. Most of themalreadyhavedefiniteconclusionsandripecalculationmethods.Themechan- icalresponsesofthemunderextremecircumstances,e.g.earthquake,explosion,fire accident,alsohaveplentyexperimental and theoretical results. Intheinitialstageofapplication,thedesignconceptandcalculationmethodofa reinforcedconcretestructurearebasedontheallowablestressandelasticanalysis, whichfollowthatofthesteelstructure.Then,theywerechangedintosinglesafety coefficient and ultimate strength analysis respectively. Now, the limit state design method, based on the probability statistics and reliability analysis, is used world- wide. In the meantime, the calculation method of the structural internal forces is also developed from the classical elastic analysis into the ultimate equilibrium methodconsideringplasticdeformation,andagainintothenon-linearanalysisalong loadinghistory.Thecombinationofthefinite-elementanalysismethodandthecom- puter technique is a very powerful means for accurate and quick analysis of a complicated reinforced concrete structure and is widely used now in engineering practice. The progress of experimental method and high technicalities of experimental equipmentandmeasuringinstrumentraisethecapabilityandaccuracyofstructural testing.Variousenvironmentalandloadingconditionsofthestructurescanbesimu- lated better and more and meticulous information and data can be obtained in the testing. These are helpful for understanding correctly the responses of the testing structure and discovering its newphysical phenomena andregularity. All of these research achievements promote deeper understanding of the behavior regularities of reinforced concrete materials and structures and raise the 4 CHAPTER 1 Introduction technicallevelsofstructuraldesignandconstruction.So,reinforcedconcretestruc- ture is developedcontinuously and will havewider prospects. 1.2 Characteristics of this course Principle of Reinforced Concrete is a special textbook of the course for post- graduatestudentsinstructuralengineeringandsimilar.Theyhavelearnedtheunder- graduate courses of Basic Structural Members of Reinforced Concrete [0-5] and Design Reinforced Concrete Structure and known the basic characteristics of rein- forcedconcreteanditsdesignmethod.Thiscoursecontainsthemaintheoreticalba- sis and experimental evidence for research and design of reinforced concrete structure, and its contents and role are just like the course ‘Strength of Materials’ forthestructureofhomogeneouslinear-elasticmaterials.However,reinforcedcon- creteismainlycomposedoftwomaterialsofdifferentproperties,i.e.reinforcement and concrete, and concrete is an inhomogeneous and non-linear material and has different values of compressive and tensile strengths. So, the mechanical behavior of reinforced concrete is more varied and complicated, and the contents of this course are more plentiful. Reinforced concrete structure is a science branch of structural engineering and certainlyfollowsthegeneralregularityofstructuralengineering.Varioustechnical requirements and questions are often raised from engineering practice, and corre- spondingsolutionsandmeasurementareobtainedbydifferentwayssuchassurvey andstatistics,experimentalinvestigation,theoreticalanalysis,calculationandcom- parison. After concluding the general variation regularity, revealing the working mechanism, establishing the physical and mathematic models, and determining thecalculationmethodandconstructionmeasures,theygobacktoengineeringprac- tice and are demonstrated, improved, and complemented. Generally, after experi- encing several cycles of practiceeresearchepractice, they will gradually approach asatisfactory answer and finally servewell the engineering. Since reinforced concrete is composed of two materials with considerably different properties, it certainly has some particularities which distinguish from the single material, e.g. steel or timber, used for the structure. Therefore, the behaviorofreinforcedconcretedependsuponnotonlythepropertiesofthetwoma- terials on their own, but also, to a greater extent, on the combination and relative comparison ofthem, for example: Differentformsofreinforcementelongitudinalortransverse,concentratedor spread, over orunder-reinforced, natural orprestressed . Relativevalueofbehaviorindicesofbothmaterialsestrengthratio,areaor volumeratio, ratioofelasticmoduli,ratio ofcharacteristicstrains,differences ofthermal strain, shrinkage, and creep .. Therefore, the load-bearing capacity and deformation behavior of reinforced concrete vary considerably. Sometimes, a special reinforced concrete can be 1.2 Characteristics of this course 5 designed and manufactured, using reasonably raw materials and proper reinforce- mentform,tosatisfythetechnicalindiceswhichfittherequirementofaparticular engineering project. It is known that concrete is an inhomogeneous and non-linear composite mate- rial, and its mechanical behavior is complicated and varied with time and its tech- nical indices are scattered considerably. In addition, the combination of reinforcement and concrete is of variform, this makes the mechanical behavior of reinforcedconcretevarysignificantly.Uptonow,manyexperimentalandtheoretical resultsofreinforcedconcretestructuralmembersundervariousloadingandenviron- mentalconditionsareobtainedandcorrespondingcalculationmethodandstructural detailingareestablishedandsatisfiedforengineeringpractice.However,thereisstill nounifiedandaccuratetheoreticaltheoryandmethodforreinforcedconcreteunder all situations. Considering these characteristics of concrete material and reinforced concrete structuralmembers, the following principlesare insisted uponin thisbook. Basing on experimental evidencee Generally, the mechanical indices of concrete material andbehaviorresponses of reinforced concrete structural memberscanonlybedeterminedaccuratelyfromreasonableandcarefultests. Therefore, acertainamountof experimental data are presented, thevariation regularitiesare concluded,themechanismis analyzed,therationalknowledge is summarized, the physical and mathematical models are established, and finally, the experimental and engineering demonstrationsare performed. Macroscopic mechanical responsee The microscopic analyses ofthe stress, strain,andcrackofstructuralconcretearehardly reachedthe accurate results, becauseofnon-uniformmicro-structure,localdefects,andscatteredbehaviorof concrete material itself. Thebehaviorsof concrete materialand reinforced concrete structure discussed inthis book representthe averagevalues ofthem withinacertainscale(e.g.about(cid:2)70mm,or3or4timesthecoarseaggregate size). It is accurate enough when theyare used inengineering practice. RegularityandmechanismanalysisofmechanicalbehavioreThebehavior responses ofconcrete materialand reinforced concretestructurevary consid- erablyunder different loadingand environmental conditions, because ofthe influences of various factors. However, the stress and deformation processes, failurepattern,andultimatestrengthofthemstillpresentcertainregularities.It ishopedtoanalyzetheirworkingmechanismsandtofindtheinherentessence ofthemechanicalcharacteristicsofthestructure,whichisrelativelystableand moreimportant.Incontrast,theparticularcalculationmethodandformulawill be changed both inform andparameters, asthe experimental data are accu- mulated,varied, or deleted. Actual mechanicalbehavior and index e Theexperimental values and the theoretical calculationvalues,listedin thisbook, for concrete materialand reinforced concrete structuralmemberaregenerally the measuredor average values. Thesevalues can be used for calculating the actual strengthand 6 CHAPTER 1 Introduction deformationofthestructure.However,therearesystematicdifferencesbetween thesevaluesandthecorrespondingnominalvaluesordesignvalues,whichare used in the structuraldesign after considering the necessarysafetyofthe structure. So, thesevalues have tobe convertedproperly andthen beused if necessary. Reflectingthe new research athome and abroade Reinforcedconcrete structure andits materials developcontinuously, newexperiences are accu- mulated and newquestions are raised inengineering practice, andrelevant experimental and theoretical achievementsappear year after year.Thebasic conceptandanalysismethodarerelativelystableandretainedinthisbook,and thenewresearchresults,anddifferentacademicpointsofviewandmethod,are contained. Inaddition,thisbookmainlyservestheresearchandanalysisofreinforcedcon- crete structure, the reinforcement and other structural detailing are, generally, not stipulatedandtherequirementsofdesigncodearealsonotincluded.Whenaprac- ticalquestioninthestructuralengineeringisdealtwith,therelevantliteraturesand references, including the designcode, have tobe consulted.
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