LRFD Design Example For Steel Girder Superstructure Bridge . PDF

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LRFD Design ExampleDecember 2003FHWA NHI-04-041forSteel Girder Superstructure BridgePrepared forFHWA / National Highway InstituteWashington, DCUS UnitsPrepared byMichael Baker Jr IncMoon Township,Pennsylvania

Development of a Comprehensive DesignExample for a Steel Girder Bridgewith CommentaryDesign Process Flowcharts forSuperstructure and Substructure DesignsPrepared byMichael Baker Jr., Inc.November 2003

Technical Report Documentation Page1.Report No.2.Government Accession No.3.Recipient’s Catalog No.5.Report DateFHWA NHI - 04-0414.Title and SubtitleLRFD Design Example for Steel Girder Superstructure Bridgewith Commentary7.9.12.Author (s)December 2003Raymond A. Hartle, P.E., Kenneth E. Wilson, P.E., S.E.,William A. Amrhein, P.E., S.E., Scott D. Zang, P.E.,Justin W. Bouscher, E.I.T., Laura E. Volle, E.I.T.Performing Organization Code8.Performing Organization Report No.B25285 001 0200 HRSPerforming Organization Name and Address10.Work Unit No. (TRAIS)Michael Baker Jr., Inc.Airside Business Park, 100 Airside DriveMoon Township, PA 1510811.Contract or Grant No.Sponsoring Agency Name and Address13.Type of Report and Period CoveredDTFH61-02-D-63001Federal Highway AdministrationNational Highway Institute (HNHI-10)4600 N. Fairfax Drive, Suite 800Arlington, Virginia 2220315.6.Final SubmissionAugust 2002 - December 200314.Sponsoring Agency CodeSupplementary NotesBaker Principle Investigator: Raymond A. Hartle, P.E.Baker Project Managers:Raymond A. Hartle, P.E. and Kenneth E. Wilson, P.E., S.E.FHWA Contracting Officer’s Technical Representative: Thomas K. Saad, P.E.Team Leader, Technical Review Team: Firas I. Sheikh Ibrahim, Ph.D., P.E.16.AbstractThis document consists of a comprehensive steel girder bridge design example, with instructional commentary based onthe AASHTO LRFD Bridge Design Specifications (Second Edition, 1998, including interims for 1999 through 2002). Thedesign example and commentary are intended to serve as a guide to aid bridge design engineers with the implementationof the AASHTO LRFD Bridge Design Specifications, and is offered in both US Customary Units and StandardInternational Units.This project includes a detailed outline and a series of flowcharts that serve as the basis for the design example. Thedesign example includes detailed design computations for the following bridge features: concrete deck, steel plate girder,bolted field splice, shear connectors, bearing stiffeners, welded connections, elastomeric bearing, cantilever abutment andwingwall, hammerhead pier, and pile foundations. To make this reference user-friendly, the numbers and titles of thedesign steps are consistent between the detailed outline, the flowcharts, and the design example.In addition to design computations, the design example also includes many tables and figures to illustrate the variousdesign procedures and many AASHTO references. AASHTO references are presented in a dedicated column in the rightmargin of each page, immediately adjacent to the corresponding design procedure. The design example also includescommentary to explain the design logic in a user-friendly way. Additionally, tip boxes are used throughout the designexample computations to present useful information, common practices, and rules of thumb for the bridge designer. Tipsdo not explain what must be done based on the design specifications; rather, they present suggested alternatives for thedesigner to consider. A figure is generally provided at the end of each design step, summarizing the design results for thatparticular bridge element.The analysis that served as the basis for this design example was performed using the AASHTO Opis software. A sampleinput file and selected excerpts from the corresponding output file are included in this document.17.Key Words18.Bridge Design, Steel Girder, Load and Resistance FactorDesign, LRFD, Concrete Deck, Bolted Field Splice,Hammerhead Pier, Cantilever Abutment, Wingwall, PileFoundation19.Security Classif. (of this report)UnclassifiedForm DOT F 1700.7 (8-72)20.Security Classif. (of this page)Distribution StatementThis report is available to the public from theNational Technical Information Service inSpringfield, Virginia 22161 and from theSuperintendent of Documents, U.S. GovernmentPrinting Office, Washington, D.C. 20402.21.No. of PagesUnclassified644Reproduction of completed page authorized22.Price

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ACKNOWLEDGEMENTSWe would like to express appreciation to the Illinois Department of Transportation, Washington State Department ofTransportation, and Mr. Mike Grubb, BSDI, for providing expertise on the Technical Review Committee.We would also like to acknowledge the contributions of the following staff members at Michael Baker Jr., Inc.:Tracey A. AndersonJeffrey J. Campbell, P.E.James A. Duray, P.E.John A. Dziubek, P.E.David J. Foremsky, P.E.Maureen KanfoushHerman Lee, P.E.Joseph R. McKool, P.E.Linda MontagnaV. Nagaraj, P.E.Jorge M. Suarez, P.E.Scott D. Vannoy, P.E.Roy R. WeilRuth J. Williams

Table of Contents1. Flowcharting Conventions2. FlowchartsMain FlowchartChart 1 - General InformationChart 2 - Concrete Deck DesignChart 3 - Steel Girder DesignChart 4 - Bolted Field Splice DesignChart 5 - Miscellaneous Steel DesignChart 6 - Bearing DesignChart 7 - Abutment and Wingwall DesignChart 8 - Pier DesignChart P - Pile Foundation Design

FlowchartsDesign Example for a Two-Span BridgeFlowcharting ConventionsA process may have an entrypoint from more than one path.An arrowhead going into aprocess signifies an entry point.StartUnique sequenceidentifierProcess descriptionReferenceProcessADesignStep #Chart # orAASHTO ReferenceUnless the process is adecision, there is onlyone exit point.A line going out of aprocess signifies an exitpoint.Flowchart reference orarticle in AASHTO LRFDBridge Design SpecificationsCommentary to provideadditional informationabout the decision essDesignStep #Chart # orAASHTO ReferenceGo to OtherFlowchartFHWA LRFD Steel Design Example1

FlowchartsDesign Example for a Two-Span BridgeMain FlowchartStartDesignStep 1DesignStep 2DesignStep 3General InformationChart 1Concrete Deck DesignChart 2Steel Girder DesignChart 3Are girdersplices required?NoDesignStep 4DesignStep 5Splices are generallyrequired for girdersthat are too long to betransported to thebridge site in onepiece.YesBolted Field Splice DesignChart 4Miscellaneous Steel DesignChart 5Go to:AFHWA LRFD Steel Design Example1

FlowchartsDesign Example for a Two-Span BridgeMain Flowchart (Continued)ADesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep 10Bearing DesignChart 6Abutment andWingwall DesignChart 7Pier DesignChart 8Miscellaneous DesignChart 9Special Provisionsand Cost EstimateChart 10DesignCompletedNote:Design Step P is used for pile foundationdesign for the abutments, wingwalls, or piers.FHWA LRFD Steel Design Example2

FlowchartsDesign Example for a Two-Span BridgeGeneral Information FlowchartChart 1StartObtain Design CriteriaIncludes:Governingspecifications, codes,and standardsDesign methodologyLive load requirementsBridge widthrequirementsClearancerequirementsBridge lengthrequirementsMaterial propertiesFuture wearing surfaceLoad modifiersObtain GeometryRequirementsIncludes:Horizontal curve dataand alignmentVertical curve data andgradesStartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10General InformationChart 1Concrete DeckDesignDesignStep 1.1Chart 2Steel Girder DesignChart 3Are girdersplicesrequired?YesBolted Field SpliceDesignChart 4Miscellaneous SteelDesignChart 5Bearing DesignDesignStep 1.2Chart 6Abutment andWingwall DesignChart 7Pier DesignChart 8MiscellaneousDesignYesChart 9Special Provisionsand Cost EstimateChart 10Does clientrequire a SpanArrangementStudy?DesignCompletedDesignStep 1.3Perform SpanArrangement StudyDesignStep 1.3NoIncludes:Select bridge typeDetermine spanarrangementDetermine substructurelocationsCompute span lengthsCheck horizontalclearanceSelect Bridge Type andDevelop Span ArrangementGo to:AFHWA LRFD Steel Design Example1

FlowchartsDesign Example for a Two-Span BridgeGeneral Information Flowchart (Continued)Chart 1StartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10General InformationAChart 1Concrete DeckDesignChart 2Steel Girder DesignChart 3Are girdersplicesrequired?DesignStep 1.4Obtain GeotechnicalRecommendationsYesBolted Field SpliceDesignChart 4Miscellaneous SteelDesignIncludes:Boring logsFoundation typerecommendations forall substructuresAllowable bearingpressureAllowable settlementOverturningSlidingAllowable pileresistance (axial andlateral)Chart 5Bearing DesignChart 6Abutment andWingwall DesignChart 7YesPier DesignChart 8Does clientrequire a Type,Size and LocationStudy?NoMiscellaneousDesignChart 9Special Provisionsand Cost EstimateChart 10Includes:Select steel girdertypesGirder spacingApproximate girderdepthCheck verticalclearanceDesignCompletedDesignStep 1.5Perform Type, Sizeand Location StudyDesignStep 1.6DesignStep 1.5Plan for Bridge AestheticsS2.5.5Determine OptimumGirder ConfigurationConsiderations include:FunctionProportionHarmonyOrder and rhythmContrast and textureLight and shadowReturn toMain FlowchartFHWA LRFD Steel Design Example2

FlowchartsDesign Example for a Two-Span BridgeConcrete Deck Design FlowchartChart 2Includes:Girder spacingNumber of girdersTop and bottom coverConcrete strengthReinforcing steelstrengthConcrete densityFuture wearing surfaceConcrete parapetpropertiesApplicable loadcombinationsResistance factorsStartStartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10General InformationDesignStep 2.1Obtain Design CriteriaChart 1Concrete DeckDesignChart 2Steel Girder DesignChart 3Are girdersplicesrequired?YesBolted Field SpliceDesignDesignStep 2.2Chart 4To compute the effectivespan length, S, assume agirder top flange width thatis conservatively smallerthan anticipated.Determine Minimum SlabThicknessS2.5.2.6.3 & S9.7.1.1Miscellaneous SteelDesignChart 5Bearing DesignChart 6DesignStep 2.3Abutment andWingwall DesignThe deck overhang regionis required to be designedto have a resistance largerthan the actual resistanceof the concrete parapet.Determine MinimumOverhang ThicknessS13.7.3.1.2Chart 7Pier DesignChart 8MiscellaneousDesignDesignStep 2.4Based on Design Steps 2.3and 2.4 and based onclient standards.Select Slab andOverhang ThicknessChart 9Special Provisionsand Cost EstimateChart 10DesignCompletedYesDesignStep 2.5Equivalent StripMethod? (S4.6.2)NoCompute Dead Load EffectsS3.5.1 & S3.4.1Other deck designmethods arepresented in S9.7.Includes moments forcomponent dead load (DC)and wearing surface deadload (DW).Go to:AFHWA LRFD Steel Design Example1

FlowchartsDesign Example for a Two-Span BridgeConcrete Deck Design Flowchart (Continued)Chart 2ADesignStep 2.6StartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10Compute Live Load EffectsS3.6.1.3 & S3.4.1General InformationChart 1Concrete DeckDesignChart 2Steel Girder DesignDesignStep 2.7Chart 3Are girdersplicesrequired?Compute FactoredPositive and NegativeDesign MomentsS4.6.2.1YesBolted Field SpliceDesignChart 4DesignStep 2.8Design for Positive Flexurein DeckS5.7.3Miscellaneous SteelDesignChart 5Bearing DesignChart 6Abutment andWingwall DesignDesignStep 2.9Check for PositiveFlexure Cracking underService Limit StateS5.7.3.4 & S5.7.1Chart 7Pier DesignChart 8MiscellaneousDesignChart 9DesignStep 2.10Design for Negative Flexurein DeckS4.6.2.1 & S5.7.3Special Provisionsand Cost EstimateChart 10DesignCompletedDesignStep 2.11DesignStep 2.12Check for NegativeFlexure Cracking underService Limit StateS5.7.3.4 & S5.7.1Design for Flexurein Deck OverhangConsiderations include:Dynamic loadallowance(S3.6.2.1)Multiple presencefactor (S3.6.1.1.2)AASHTO momenttable for equivalentstrip method(STable A4.1-1)Resistance factor forflexure is found inS5.5.4.2.1. See alsoS5.7.2.2 andS5.7.3.3.1.Generally, the bottomtransversereinforcement in thedeck is checked forcrack control.The live load negativemoment is calculatedat the design section tothe right and to the leftof each interior girder,and the extreme valueis applicable to alldesign sections(S4.6.2.1.1).Generally, the toptransversereinforcement in thedeck is checked forcrack control.S5.7.3.4, S5.7.1 & SA13.4Go to:BFHWA LRFD Steel Design Example2

FlowchartsDesign Example for a Two-Span BridgeConcrete Deck Design Flowchart (Continued)Chart 2For concrete parapets,the case of verticalcollision never controls.BDesign Overhangfor HorizontalVehicular CollisionForceSA13.4.1DesignCase 1Check atCaseInside Face1Aof ParapetDesignCase 2Check atCaseDesign1B Section inOverhangDesign OverhangforVertical CollisionForceSA13.4.1Check atCase Design1C Section inFirst SpanDesignCase 3Design OverhangforDead Load andLive LoadSA13.4.1Check atCase Design3A Section inOverhangCheck atCase Design3B Section inFirst SpanAs(Overhang) maximum of theabove fivereinforcing steelareasStartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10General InformationChart 1Concrete DeckDesignChart 2YesSteel Girder DesignAs(Overhang) As(Deck)?NoChart 3Are girdersplicesrequired?YesBolted Field SpliceDesignUse As(Overhang)in overhang.Use As(Deck)in overhang.The overhangreinforcing steelmust satisfy boththe overhangrequirementsand the deckrequirements.Chart 4Miscellaneous SteelDesignChart 5Bearing DesignDesignStep 2.13Chart 6Check for Crackingin Overhang underService Limit StateS5.7.3.4 & S5.7.1Does not controlthe design inmost cases.Abutment andWingwall DesignChart 7Pier DesignChart 8DesignStep 2.14Compute Overhang Cut-offLength RequirementS5.11.1.2MiscellaneousDesignChart 9Special Provisionsand Cost EstimateChart 10Go to:CDesignCompletedFHWA LRFD Steel Design Example3

FlowchartsDesign Example for a Two-Span BridgeConcrete Deck Design Flowchart (Continued)Chart 2CDesignStep 2.15StartDesignStep 1DesignStep 2DesignStep 3NoDesignStep 4DesignStep 5DesignStep 6DesignStep 7DesignStep 8DesignStep 9DesignStep10Compute OverhangDevelopment LengthAppropriatecorrection factorsmust be included.S5.11.2General InformationChart 1Concrete DeckDesignChart 2DesignStep 2.16Steel Girder DesignDesign Bottom LongitudinalDistribution ReinforcementS9.7.3.2Compute EffectiveSpan Length, S,in accordancewith S9.7.2.3.Chart 3Are girdersplicesrequired?YesBolted Field SpliceDesignDesignStep 2.17Chart 4Design Top LongitudinalDistribution ReinforcementS5.10.8.2Based ontemperature s SteelDesignChart 5Bearing DesignChart 6DesignStep 2.18Design LongitudinalReinforcement over PiersAbutment andWingwall DesignChart 7Pier DesignChart 8Miscellan

The deck overhang region is required to be designed to have a resistance larger than the actual resistance of the concrete parapet. Other deck design methods are presented in S9.7. Are girder splices required? Bolted Field Splice Design Chart 4 Design Step 4 Concrete Deck Design Chart 2 Design Step 2 Steel Girder Design Chart 3 Design Step 3 No ...