Recommended Practice For Precast Prestressed Concrete .
Special ReportRecommended Practice forPrecast Prestressed ConcreteComposite Bridge Deck PanelsPrepared for thePCI Bridge Producers CommitteebyRoss Bryan Associates, Inc.Nashville, TennesseeBased on the latest research and field experience,this PCI Committee report presents recommendationsfor the design, production, handling, shipping anderection of precast prestressed concrete compositebridge deck panels.The report also covers product tolerances, crackingand repair methods, as well as plant and jobsiteinspection procedures.A design example, using the AASHTO Specifications,is included together with several design aids.PCI JOURNAL, March-April 1988 7
CONTENTSNotation. 70Introduction. 72Chapter1—General . 731.1 —History1.2 — Materials1.3 — Advantages1.4 — Design ConsiderationsChapter2 — Design . 752.1 — General Information2.2 - Panel Thickness and Size of Prestressing Strand2.3 — Strand Location2.4 — Factored Moment Strength and Strand Development2.5 — Panel Width and Span2.6 — Stress Transfer and 28-Day Strengths2.7 — Corrosion Protection2.8 — Fatigue2.9 — Strand Projections2.10 — Bearing Systems2.10.1 —General2.10.2 — Temporary Bearing2.10.3 — Permanent Bearing2.10.4 — Installation Profile2.11 — Load Distribution2.12 — Composite BehaviorChapter3 — Manufacture . 823.1 — Forms3.2 — Strand Positioning3.3 — Strand Surface Condition3.4 — Concrete Work3.5 — Curing3.6 — Detensioning Procedures68
3.7 — Stripping3.8 — StorageChapter 4 — Product Tolerances, Cracking andDamageRepair .844.1 — Tolerances4.2 —Cracking4.2.1 — Types of Cracking4.2.2 — RepairsChapter 5 — Shipping and Handling . 865.1 — Panel Length and Width5.2— Support on Trailers5.3 — Multiple Panel Handling5.4 — Jobsite StorageChapter6 — Erection . 876.1 — Panel HandlingChapter7 — Inspection . 877.1 — Plant Inspection7.1.1 —Forms7.1.2 — Strand Position7.1.3 — Strand Surface Condition7.1.4 — Detensioning7.1.5—Stripping7.1.6 — Post-Pour Inspection7.1.7 — Storage and Preshipment Inspections7.2 — Jobsite Inspection7.2.1 — Unloading Inspection7.2.2 — Temporary Storage7.2.3 — In-Place InspectionReferences. 89AppendixA — Design Example . 91Appendix B — Sample Design Curves . 98PCI JOURNAUMarch-April 198869
E,E ;4 , mESf f ;70– area (in,') area of prestressingsteel (in. 2 ) unit width of deckpanel (in.) effective width of topslab (in.) distance from centroidal axis to bottomof deck panel (in.) loss of prestress due tocreep of concrete (psi) loss of prestress due torelaxation of prestressing steel (psi) distance from centroidal axis to top ofdeck panel (in.) distance from extremecompression fiber tocentroid of prestressing force (in.) square of distance fromcomposite sectioncentroidal axis to center of gravity of element being considered(in. 2 ) nominal diameter ofprestressing steel (in.) modulus of elasticity ofconcrete at time ofstress transfer (psi)modulus of elasticity ofdeck panel concrete(ksi) modulus of elasticity ofprestressing steel (psi)– modulus of elasticity ofcast-in-place top slabconcrete (ksi) loss of prestress due toelastic shortening (psi) bending stress at hottom of deck panel (psi) compressive strengthof concrete at 28 days(psi) compressive strengthfedf,.f,.Of8fff ;,ftopfroPn„ h„IldlzLMMro,f;„„M«of concrete at time ofinitial prestress (psi) concrete stress at center of gravity of prestressing steel due toall dead loads exceptdead load present attime prestressing forceis applied (psi) concrete stress at center of gravity of prestressing steel due toprestressing force anddead load of memberimmediately afterstress transfer (psi) modulus of rupture ofconcrete (psi) total prestress loss (psi) ultimate strength ofprestressing steel (ksi) effective stress in prestressing strand afterlosses (ksi) average stress in prestressing steel at ultimate load (ksi) bending stress at top ofcast-in-place top slab bending stress at top ofdeck panel (psi) thickness of deckpanel (in.) gross section momentof inertia (in.) strand developmentlength distance from end ofprestressing strand tocenter of deck panel(in.) span length (ft) bending moment (lb-ft) continuous span bending moment (lb-ft) moment causing flexural cracking at sectiondue to externally applied loads
total bending momentMerialMfipsi .MDLM„Mj mpl.M.np*P oll WwrSSHrrfrat which section willcrack (lb-ft)– service load moment tohe used for design(lb-ft) bending moment resulting from deadloads (lb-ft) nominalmomentstrength of section bending moment necessary to overcomeprestress force (lb-ft) simple span bendingmoment (lb-ft) factored moment atsection -- 4M,, (lb-ft) modular ratio of elasticity ratio of prestressingsteel,A alhd assumed effective prestress force per strandafter all losses (kips) effective span lengthas defined under"Span Lengths" Article 324.1 of AASHTOSpecifications (ft) loss of prestress due toPCI JOURNAL/March-April 1988concrete shrinkage(psi) section modulus ofS boftomcomposite section withrespect to bottom ofdeck panel (in.-)S bnrinm p,t mbare"- section modulus ofuntopped deck panelwith respect to itsbottom (in.3) section modulus ofS t.pcomposite section withrespect to top of composite slab (ins) section modulus ofStop,, e' us,composite section withrespect to top of deckpanel (in.')S ar ,rP section modulus of untopped deck panel withrespect to its top (in.:')W uniform load (psi) distance from bottomYof section to center ofgravity of elementbeing considered (in.)Yroa distance from centroidal axis of composite section to extremefiber in compression(in.)71
INTRODUCTIONPrecast and prestressed concretecomposite bridge deck panels are usedwith cast-in-place concrete to provide aconvenient and cost effective method ofconstruction for concrete bridge decks.The panels are usually precast at amanufacturing plant. They are truckedto the bridge construction site and liftedby cranes onto concrete or steel girders.There, they span the opening betweengirders and serve as permanent forms forthe cast-in-place concrete topping thatcompletes the bridge deck The precastconcrete panels and concrete toppingbecome composite and the panels contain all of the required positive momentreinforcement between girders.Precast and prestressed concretecomposite bridge deck panels will hereferred to, in this report, as "compositedeck panels" or simply as "deck panels."Composite deck panels are similar toother prestressed concrete compositemembers with regard to applicationsand design considerations, There are,however, situations that are unique tocomposite deck panels due to the waythe panels are produced and used.A 1986 survey conducted by the Prestressed Concrete Institute (PCI) contacted all State Highway Departmentsin the United States, numerous Tollwayand Transportation Authorities and PCImember plants to determine currentspecifications and methods of production. Some agencies have unique approaches to the design and use of composite deck panels. Similarly, a fewmanufacturers have developed theirown methods for fabrication of theseproducts, A review of the survey responses, however, reveals that there isuniformity between most agency specifications and prevalent methods of production.72The purpose of this report is to present recommendations for the design,manufacture and use of composite deckpanels. These recommendations aresupported by the referenced research,the analysis of the survey data, and thecollective experience and judgment ofthe precast and prestressed concrete industry. The practices suggested in thisreport, where identified in use, havebeen shown to be performing favorablyin locations across North America, for aslong as 35 years. The recommendationsreported herein may be applied confidently by designers, precasters andcontractors with the expectation of excellent performance for lowest possiblecost.This report was prepared by RossBryan Associates, Inc. of Nashville,Tennessee, with input and directionfrom the PCI Bridge Producers Committee, the PCI Committee on Bridgesand the Technical Activities Committee.All reasonable care has been used toverify the accuracy of material containedin this report. However, the reportshould be used only by those experienced in structural design and shouldnot replace sound structural engineering judgment.This report is intended to address design, fabrication, shipping, handling,and erection requirements for precastprestressed concrete composite bridgedeck panels. All designs herein conformto the 1983 AASHTO Standard Specifications for Highway Bridges, includingthe 1984 through 1987 Interim Specifications.'For the fabricator and the contractor,this report is intended as a guide for theproduction of high quality compositedeck panels and their proper installation.
1.1 HistoryComposite deck panels are widelyused in the construction of bridges inthe United States. The 1986 survey conducted by PCI indicated that twentyone State Highway Departments andthree Turnpike Authorities havespecified the use of composite deckpanels.The panels were first used in the early195Os for construction of bridges on theIllinois TolIway. A number of statesbegan to use the panels in the late1960s and early 1970s. Also, several research projects were undertaken andcompleted during that time. 2-11 The results of that research along with earlierdesign experience form the basis forcurrent design practice.The earliest installations of deckpanels are nearing 35 years of age, andthe panels are performing well. 7 In morerecent years, isolated problems havebeen reported, especially cracking inthe composite top slab and excessivebowing of deck panels prior to installation. It was these concerns thatprompted the producer and user surveyand has resulted in this recommendedpractice report. These problems and therecommended solutions are discussedin this report.Additional historical information, references and photographs may be foundin the special state-of-the-art report,"Precast Prestressed Concrete BridgeDeck Panels," prepared by the PCICommittee on Bridges."1.2 MaterialsComposite bridge deck panels aretypically cast using low slump concretemixes. The use of water reducers andplasticizers are sometimes specified inorder to attain the required stress transfer and 28-clay strengths. Some agenciesspecify the use of rust or corrosion inPCI JOURNAUMarch-April 1988hibitors in the mixes; however, mostrely on the cast-in-place top slab to provide sufficient cover to prevent chloridepenetration into the composite deckpanels. Requirements for air entrainment in the composite deck panels vary.The types of aggregates used varywidely across the country. Aggregatesize should be no larger than 3/4 in, toensure that concrete is thoroughly consolidated below the strand in the shallow pan forms and to achieve concretestrengths specified.Strand used in deck panels includesnearly every size and type of strand produced. Trends now are toward the use of% in. diameter strand. The practice ofstrand use varies depending on considerations of strand development lengths.Typically, mild steel reinforcement isGrade 60 steel or welded wire fabric.1.3 AdvantagesCommon bridge deck constructionconsists of prestressed concrete girdersor steel girders supporting a roadwaydeck. This deck can be formed as a fulldepth cast-in-place slab or it can be constructed using precast prestressed composite bridge deck panels as shown inFig. 1.lithe bridge deck is cast in place forits full depth, forms must be installedand later removed. Forming costs arehigh and the installation and removal offorms is time consuming. In some situations this creates safety hazards to trafficunder the construction or to the workersthemselves. Stay-in-place metal formsare sometimes used. These also eliminate the need for form removal, butthey are subject to long term corrosionand do not replace or reduce the bottomreinforcement as they do not act compositely with the concrete slab.Precast prestressed concrete composite bridge deck panels eliminate theneed for most of this expensive forming73
CAST-IN-PLACE TOP SLABDECK PANELCAST-IN-PLACE TOP SLABpo- II. II 'DECK PANELFig. 1. Typical details of deck panels on prestressed girder(top) and steel girder.operation. The deck panel and cast-inplace top slab act compositely and resultin a significant material and cost savings. The prestressing strands in thedeck panels provide the necessary bottom reinforcement in the composite slabsystem. This eliminates the need for onelayer of mild steel reinforcement in thedeck. The deck panels are manufacturedwith dense, high strength concrete thatis more resistant to chloride penetration.Because the deck panels are prestressed, the designer has the ability tocontrol stresses in the important tensilestress zone.Composite bridge deck panels aremanufactured in established plantswhere proven production and qualitycontrol methods result in a productwhich conforms to specifications Mil74lions of square feet of precast prestressed concrete composite bridge deckpanels have been manufactured and instaIled. They have proven to be a soundeconomical alternative to conventionalforms and are usually chosen for construction when specifications permitalternate solutions.1.4 Design ConsiderationsThe design of precast prestressedconcrete composite bridge deck panelsmust include an analysis of the panelsfor stresses due to handling and duringconstruction as well as ultimate strengthof the composite section.Design drawings should show everyaspect of production and installation ofthe composite deck panels, including
storage instructions, bearing details, andall other special considerations.Shop drawings prepared by the fabricator must include all information contained on the design drawings as well asany special information necessary forproduction. Composite deck panellengths should be carefully selectedwith consideration given to tolerancesfor girder horizontal sweep in order toachieve proper bearing.When composite deck panels are usedon steel or prestressed concrete girders,the designer should recognize that shearstuds on steel girders and projectingstirrups on concrete girders must be lo-cated to minimize interference withcomposite deck panel placement.Torsional stresses are typically not induced in composite deck panels inbridges with straight girders. Torsion indeck panels due to girder movementshould be considered in the designwhen composite deck panels are usedon bridges with horizontally curvedsteel girders or box sections. These arespecial cases which should be carefullystudied.Stresses from differential movementof long, relatively flexible steel girdersshould also he evaluated by the bridgedesigner.CHAPTER 2- DESIGN2.1 General InformationThe design of precast prestressedconcrete composite bridge deck panelsis based on the requirements in theStandard Specifications for HighwayBridges published by the American As-sociation of State Highway and Transportation Officials (AASHTO).'As with prestressed concrete members in general, composite deck panelsare checked for transfer stresses, handling stresses, service load stresses, andfactored strength in shear and flexure.Research has shown that compositedeck panels as presently designed perform well under fatigue test conditions,and therefore no special provisions areneeded for fatigue. 2-6 Strand slippage isnot a common problem and tolerancesfor stressing forces as established byspecifying agencies are enforced.Although precast prestressed concretecomposite deck panels have been usedwith success for many years, concernsrelating to their production and use, aswell as differences between agenciesspecifying the products, have raisedsome questions. This chapter addressesthose questions and evaluates their efPCI JOURNALMarch-April 1988feet on design of the composite deckpanels.2.2 Panel Thickness and Size ofPrestressing StrandPanel thicknesses commonly used forcomposite deck panels have rangedfrom 2'/s to 4½ in. The panels should bemade as light as practicable for handlingpurposes, but this must be eva]uatedconsidering the potential for damage ifthe sections are too thin.The recommended minimum composite deck panel thickness for generaluse is 3 in. The panel thickness is animportant factor in choosing the size ofstrands to be used. The relationship ofpanel thickness to strand diametershould be approximately 8:1 as shownbelow. This has been reported to givevery satisfactory results.Panel Thickness Maximum strand size3 in.% in,3V2 in.The in.4 in. or larger½ in.The absolute minimum composite75
deck panel thickness should be 2½ in.Panels with this thickness, however, require special care during manufacturing, handling, and erection. With % in.strands, the resulting clear concretecover is 1'i in. Article 9.25.1.2.2 of theAASHTO specifications requires 1 in.minimum cover on prestressing strandsin the bottom of slabs. Full scale tests ofbridges with composite deck panels indicated that 1 in, of concrete cover onthe strands in the panels was adequate.,,Deviations from this recommendationare possible, but consideration must hegiven to the possibility of splitting of thepanel ends due to prestress transferforces. Use of thin panels or largestrands may require special end zonereinforcement, Deviations should besubmitted to the specifying agency forapproval.2.3 Strand LocationThe majority of composite deckpanels produced over the years havehad strands located at the centroid of thesection although eccentric prestressingcan result in significant cost savingsover concentric prestressing.Uniform spacing of the prestressingstrands is recommended to preventsplitting cracks in the panels.' Approximately equal strand patterns may beused where equally spaced strand patterns do not coincide with the compositedeck panel width or jacking headerspacing. "a2.4 Factored Moment Strength andStrand DevelopmentArticle 9.27 of the AASHTO Specifications provides a relationship fordetermining the development length ofprestressing strand:Development length:td (f – %f,)D(9 -3 2)where f ,, is the average stress in the pre76stressing steel at ultimate load.The term f also occurs in the equation for factored moment strength, Mu,.Article 9,17.2, Eq. (9-13). However, thevalue of J' may not always he the sameas applied to these two equations. Thereason for this is that when short lengthdeck panels are used, there may not heenough total length available to developthe full strength of the prestressingstrands.Article 9.17.4.2 states that the maximum value for f at ultimate load belimited to:f eu l %Df(9-19)where the term 1 r is the distance fromthe end of the prestressing strand to thecenter of the panel. In other words, astrand can develop a maximum value forf [Eq. (9-17) ] if the full developmentlength, 1 d , is available. When l ,x is lessthan l d , the maximum stress in thestrand will be correspondingly less.This will consequently reduce the valueof f,*, and the design flexural strength,M.This is demonstrated graphically inFig. 2. The prestressing reinforcementshown for this panel is insufficient for aspan of less than about 5 ft. This is because the allowable f has been significantly reduced due to the small value ofl. At a span length of just over 5 ft thereduction of f * is at its most criticalpoint, but as the span increases, theamount of the reduction becomes lesscritical because M„ is increasing muchfaster than the factored moment. For thisreason, in deck panels with longerspans, the formation of some splittingcracks or damage resulting from handling at the ends should not necessarilybe a cause for rej
Chapter 4 — Product Tolerances, Cracking and DamageRepair .84 4.1 — Tolerances 4.2 —Cracking . 87 7.1 — Plant Inspection 7.1.1 —Forms 7.1.2 — Strand Position . 98 PCI JOURNAUMarch-April 19
Structural Systems (A TLSS) on gravity load floor systems for precast/prestressed concrete buildings. The main objective of the research is to develop precast/prestressed concrete floor systems for gravity loads for application in occupied office buildings with a regular spacing of columns. Five proposed concepts for precast/ prestressed
majority of traditional design challenges (Precast/Prestressed Concrete Institute, 2010). Various uses of precast concrete exist in the form of double and single tees, slabs, panels, beam and girders, stairs, and columns (Canadian Precast/ Prestressed Concrete Institute, 2007) (Figure :1). In South Africa, precast floor systems are the most com
Precast/Prestressed Concrete Institute, Design Handbook-Precast and Prestressed Concrete: Code of Standard Practice for Precast/Prestressed Concrete (PCI MNL-120) Structural Material Specifications Concrete Foundations (Pile Caps and Grade Beams): 6,000 p
Section 11-8 Design Guidelines of Precast Prestressed Girder1 s Furthermore, precasprecast girders can be more effective and economical when the girder quantity is large and details are repeatable. Project Engineers encouraged to consider precast prestressed concrete girder superstructures as an a lt ernat ive during the planning phase.
Abstract--A hollow core slab is a precast prestressed concrete member with longitudinal hollow cores that reduce its self-weight. This paper presents the effects of openings on flexural and shear behavior of precast prestressed hollow core slabs. Three full-scale hollow core slabs of dimensions 4100x1200x160 mm were tested.
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Founded in 1954, The Precast/Prestressed Concrete Institute (PCI) is a technical institute for the precast concrete structures and systems industry. PCI develops maintains, and disseminates the Body of Knowledge for the design, fabrication, and construction of precast concrete structures and systems. PCI develops consensus
Size Matters: Coastal Precast Systems of Chesapeake, Va., manufactured 59 precast, prestressed column caps weighing 300 tons each for the New NY Bridge project. Learn more about how these pieces and other precast concrete components will contribute to the bridge's projected 100-year service life on page 18. Photo courtesy of Coastal Precast .
