Bridge design and evaluation : LRFD and LRFR

437 Pages·2013·7.29 MB·English

by  Gongkang Fu

Bridge Design and Evaluation
Bridge Design
and Evaluation
LRFD and LRFR
GongkangFu
John Wiley & Sons, Inc.
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LibraryofCongressCataloging-in-PublicationData:
Fu,Gongkang.
Bridgedesignandevaluation:LRFDandLRFR/GongkangFu.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-470-42225-0(cloth);ISBN978-1-118-32993-1(ebk);ISBN978-1-118-33220-7(ebk);
ISBN978-1-118-33268-9(ebk);ISBN978-1-118-40255-9(ebk);ISBN978-1-118-40256-6(ebk);
ISBN978-1-118-40257-3(ebk)
1.Bridges–Designandconstruction–Textbooks.2.Bridges–Evaluation–Textbooks.
3.Bridges–Maintenanceandrepair–Textbooks.4.Loadfactordesign.I.Title.
TG300.F822013
624.2(cid:1)52–dc23
2012026192
PrintedintheUnitedStatesofAmerica
10987654321
TomyfatherwhotaughtmealgebrawhenIdidnothaveahighschooltoattend,
andtomymotherwhotaughtuslovewhenwedidnothaveenoughfood.
Contents
Preface xi
1
Introduction 1
1.1 BridgeEngineeringandHighwayBridgeNetwork 1
1.2 TypesofHighwayBridges 2
1.3 BridgeConstructionandItsRelationtoDesign 7
1.4 AASHTOSpecificationsandDesignandEvaluationMethods 9
1.5 GoalsforBridgeDesignandEvaluation 11
1.6 PreliminaryDesignversusDetailedDesign 11
1.7 OrganizationofThisBook 12
References 14
2
Requirements for Bridge Design and Evaluation 15
2.1 GeneralRequirements 15
2.2 LimitStates 16
2.3 Constructability 20
2.4 Safety 21
2.5 Serviceability 31
2.6 Inspectability 41
2.7 Economy 41
2.8 Aesthetics 42
2.9 Summary 44
References 45
Problems 45
vii
viii Contents
3
Loads, Load Effects, and Load Combinations 47
3.1 Introduction 47
3.2 PermanentLoads 48
3.3 TransientLoads 63
3.4 LoadCombinations 83
References 92
Problems 92
4
Superstructure Design 101
4.1 Introduction 101
4.2 HighwayBridgeSuperstructureSystems 103
4.3 PrimaryComponentsofHighwayBridgeSuperstructure 106
4.4 DeckSystems 110
4.5 Deck-SupportingSystems 121
4.6 DesignofReinforcedConcreteDeckSlabs 135
4.7 DesignofSteelIBeams 177
4.8 DesignofPrestressedConcreteIBeams 247
References 300
Problems 300
5
Bearing Design 303
5.1 Introduction 303
5.2 TypesofBridgeBearing 304
5.3 AppropriateSelectionofBearings 313
5.4 DesignofElastomericBearings 314
References 333
Problems 333
6
Substructure Design 335
6.1 Introduction 335
6.2 Piers 340
6.3 Abutments 346
6.4 Foundations 349
6.5 DesignofPiers 353
6.6 DesignofAbutments 357
References 393
Problems 393
Contents ix
7
Highway Bridge Evaluation 395
7.1 Introduction 395
7.2 InspectionandConditionRating 397
7.3 LoadRating 401
7.4 FatigueEvaluationforSteelComponents 416
References 419
Problems 419
Index 421
Preface
Since the first edition of the American Association of State Highway and
Transportation Officials (AASHTO) LRFD Bridge Design Specifications in
1994, U.S. highway bridge design has been moving towards load and
resistance factor design (LRFD). Prior to that, for more than a half of
century, highway bridge design practice has been using the load factor
design (LFD) and service load design (SLD), according to the AASHTO
StandardSpecificationforHighwayBridges.Furthermore,in2003,thefirst
editionofAASHTOManualforConditionEvaluationandLoadandResistance
FactorRating(LRFR)ofHighwayBridges wasissuedforbridgeevaluationand
load rating. In 2007, AASHTO mandated the LRFD specifications in the
UnitedStatesaftermorethanadecadeofpreparation,includingtrialuse
and software development. With the Federal Highway Administration’s
(FHWA’s) requirement and also for consistency, a number of states have
started the practice of LRFR for bridges designed according to LRFD.
This introductory book covers the LRFD and LRFR methods for highway
bridgesasatextbookforafirstundergraduateand/orgraduatecourseon
highwaybridgedesignand/orevaluation.
ThesixtheditionoftheAASHTOLRFDBridgeDesignSpecifications issued
in2012wasthelatestdesigncodewhenthisbookwasprepared.Therefore,
in this book, this edition of specifications is referred to as the AASHTO
specifications,AASHTOdesignspecifications,orAASHTOLRFDspecifica-
tions, dependingon what is beingemphasized in the context. For bridge
evaluation andload rating,thesecond edition of the AASHTOManualfor
Bridge Evaluation dated 2011 was the latest when this book was prepared,
whichisreferredtoastheAASHTO manualorAASHTOevaluationspeci-
fications,dependingoncontext.Thissetofspecificationsisalsosometimes
referredtoastheAASHTOspecificationscollectivelyalongwiththeLRFD
specifications.
xi
xii Preface
While some information provided here may be used for preliminary
design of highway bridges, this book mainly covers the detailed design
of short- to medium-span highway bridges according to the AASHTO
specifications. In addition, structural design is the main focus in detailed
design. In other words, detailed design covered in this book proceeds
with given or already optimized structure type, span arrangement, span
length, and so on. This situation is assumed so that the student will not
havetobeconcernedwithwhetherthebeing-designedbridgeneedstobe
optimized,withrespectto spantype,length,width,geometricparameters,
and so on, whichwould unlock everythingand leave no directionfor the
studenttofollow.Ontheotherhand,thestudentneedstounderstandthat
determinationofthesefactorsmayrequireadditionalinformationand/or
knowledgenot completely covered inthis book, such ascost effectiveness
of alternativespan lengthsand/or arrangementsassociated withdifferent
materialsandclimateconditions,andsoon.
Furthermore,this book has a focus on short- to medium-span highway
bridgesfordetaileddesign.Theshort- andmedium-spanlengthshereare
definedas thosein therangeof 20to about 200ft, withinthe application
rangeofthespecifications.Thisbookalsocoversthosebridges’evaluation
(particularlyloadrating)accordingtotheAASHTOmanual.Forthegiven
spanlengthrange,windisusuallynotthemajorgoverningload.However,
longerhighwaybridgespanswhosedesignofteniscontrolledbywindload
effect still need to meet the requirements of the AASHTO specifications
presentedhere.Therefore,understandingtherequirementscoveredinthis
book may be viewed asa prerequisiteto studying long-spanbridgedesign
andevaluation.
This book has seven chapters. Chapter 1 is an introduction to bridge
engineering, including design and evaluation. Chapter 2 covers both
the general and specific requirements in the AASHTO specifications for
designing highway bridges. The concepts of structural reliability are also
presented, which were used for the calibration of both sets of AASHTO
specificationsfocusedonhere.Chapter3presentsfurtherdetailedspecific
requirementsofthespecificationsforloads,loadeffects, andtheircombi-
nationsforhighwaybridgecomponents.Chapter4ofthisbookcoversthe
superstructurepartofbridgedesign,Chapter5thebearings,andChapter
6 the substructure. Chapter 7shifts focus from designto evaluation (load
rating)ofthesamebridgescoveredinthebook.
This book is designed as a textbook for first courses of undergraduate
and/or graduate studies on highway bridge design and/or evaluation
according to current AASHTO specifications. For an undergraduate
course of three credit hours, Chapters 1, 3, and 4 (or along with 5) are
recommended to be covered. If the undergraduate course is designed
for four credit hours, Chapter 5 (or 6) may be added. For a graduate
course, Chapters 1 through 6 may be covered for three credit hours, and
Chapter 7 can be added for four credit hours. Structural analysis will be
Preface xiii
a prerequisitefor using this textbook, and steel and concrete designs are
preferredtobeprerequisitesbutmaybeallowedascorequisites.Successful
completion of the course willenable the student to perform duties of an
entry-level engineer in bridge design and evaluation, according to the
currentAASHTOspecifications.
Anotheralternativewayofusingthisbookistoteachonlyitsbridgeanal-
ysisandtherelatedexamplesorportionsoftheexamples.Itcanbepartofa
structuralanalysiscourseoranindependentcourseateitherundergraduate
orgraduatelevel.
The examples included in this book can be used without referring to
thetext.Suchusecanbeparticularlyconvenientforreviewafteralevelof
understandingof therelevanttextmaterialisestablished.Therefore,they
mayalsoserveasahelpfulreferenceforjuniorengineerswithlimitedfamil-
iaritywithbridgedesignand/orevaluationandthosewhoarepreparingfor
aprofessionalengineerlicenseexam,particularlywherebridgedesignisa
requiredsubject.
Acompletehighwaybridgewillbevisibletothestudentwhenseveralof
theseexamplesareintegratedtogether,includingitsloadratingofprimary
members.Forinstance,thefollowingexamplescanmakeatypicalhighway
commonlyseeninoneoftoday’s bridgedesignoffices:thereinforcedcon-
cretedeckdesignedinExamples4.1,4.3,and4.4plusthesteelplategirders
designedinExamples4.9to4.11plustheshearstudsdesignedinExample
4.8plus the abutment designedinExamples6.1to 6.4.Examples7.1and
7.2thenprovidethebridge’ssuperstructurememberloadrating.Ofcourse,
thedeckdesigninExample4.1maybereplacedbyanotherdeckdesignin
Example4.2.Furthermore,thesuperstructuresteelbeamsinExamples4.9
to 4.11 may be replaced by the prestressed concrete beams in Examples
4.12to 4.14 or another steel beam superstructurein Examples4.5 to 4.7.
Tominimizeinconvenientcrossreferencingbetweendifferentexamples,a
fewstepsofcalculationintheseexamplesmayhavebeenrepeatedinother
examples, so that such cross referencing willinvolve only nearby pages if
atall.
The student is not required to have the AASHTO LRFD or LRFR
specifications while taking a course using this book. However, reference
to the AASHTO specifications provisions are provided in the text so that
the instructor and/or student can easily find more information in the
specifications if needed. It is also worth noting that AASHTO offers U.S.
faculty three free AASHTO publications a year,whilethe faculty needsto
payforshippingandhandling.
Thisbookisbasedontheauthor’sexperienceofteachingbridgedesign
and evaluationat Wayne State University andIllinoisInstitute of Technol-
ogy for 16 years. Many students of the author have assisted in preparing
the manuscript. He would like to express gratitude to them: Drs. Dinesh
DevarajandPang-joChunandMessrs.TapanBhatt,JasonDimaria,Alexan-
derLamb,andJustinSikorski.Bridgedesignplansand/orcalculationsalso