Presentation on theme: "Connection Details for Prefabricated Bridge Elements and Systems"— Presentation transcript:
1 Connection Details for Prefabricated Bridge Elements and Systems Michael P. Culmo, P.E.Vice President of Transportation and StructuresCME Associates, Inc., East Hartford, CT
2 Learning Outcomes After completing this Module, you will be able to: identify roadblocks to accelerated bridge constructionidentify the resources for locating Connection Details for PBESdescribe features of PBES that improve the quality of the finished productrecognize a typical construction schedule for a bridge built with PBESrecall ways to save money by using ABC and PBESAfter completing this Module, you will be able to:identify roadblocks to accelerated bridge constructionidentify the resources contained in Connection Details for PBESdescribe features of PBES that improve the quality of the finished productrecognize a typical construction schedule for a bridge built with PBESrecall ways to save money by using PBES
3 Roadblocks to Accelerated Construction The primary concerns that owner agencies have with respect to adopting accelerated construction techniques are:Need for Quality DetailsDurabilityDesign Methodologies and TrainingConstruction MethodologiesFHWA has polled transportation agencies in the past to determine the roadblocks to using ABC. The responses are as shown.
4 “Connections Details for Prefabricated Bridge Elements and Systems” FHWA has developed this manualThis publication is intended to provide information that will go a long way to answering all four of the previous concerns.Focus on details that have been used in the past.In response to the concerns from agencies, FHWA developed a manual that focused on connection details that have been successfully used in the past.
5 “Connections Details for Prefabricated Bridge Elements and Systems” Project Goals: Gather details of Connections that have been used on accelerated bridge construction projectsInvestigate transfer of technology from other markets into the bridge marketParking GaragesStadiumsBuildingsThe details were gathered from transportation agencies and other industries, which turned out to be a key component of the work. Accelerated construction is also used in vertical construction. Many of the details used in this industry are transferable to bridge construction.
6 “Connections Details for Prefabricated Bridge Elements and Systems” All details need to pass a critical test before being published in the document:Does the connection result in a rapid construction process?Does the connection transmit the forces between elements effectively?Is the connection durable?Is it cost effective and easy to construct?If a process or connection is proprietary, is there more than one supplier?It is imperative that all detail pass these critical test in order to ensure proper performance and a 75 year service life
7 Sources of Data State DOT’s Federal Agencies Questionnaires sent viaFederal AgenciesResearchers (previous and current)Producers/FabricatorsThe connection details were gathered from the following sources.
8 ForwardTable of ContentsSection 1General Topics1.1Introduction1.2Accel. Construction Overview1.3Applicability to Typical Bridges1.4Typical Connection Types1.5Seismic Considerations1.6Materials1.7Tolerances1.8Fabrication and ConstructionSection 2Superstructure Connections2.1Deck Systems2.2Adjacent Butted Beam Systems2.3Decked Stringer Systems2.4Modular Superstructures2.5Connections to SubstructuresSection 3Substructure Connections3.1Pier Systems3.2Abutment Systems3.3Wingwalls and Retaining WallsSection 4Foundation ConnectionsAppendicesAppendix ANotationsAppendix BConnection Design ExamplesAppendix CStandard ProductsAppendix DSample Const. SpecificationsAppendix ECase StudiesAppendix FGlossaryThe manual is organized so that users can easily find details. The sections are divided by parts of the bridge that are defined in AASHTO. Superstructure, Substructure and Foundations.Manual Organization
9 Connection Data Sheets Detail data sheets were developed that are similar to materials cut sheets. Users can gather enough information to complete a structure type study. Contact information and detail performance are included. Users can contact the agency that submitted the details and find out more information as their project proceeds.
10 Precast Cantilever Abutments Samples of details included in the manual: Precast cantilever abutment connections
11 Precast Integral Abutments Samples of details included in the manual: Precast integral abutment connections
12 Precast PiersSamples of details included in the manual: Precast pier bent connections
13 Precast PiersSamples of details included in the manual: Precast pier cap connections
14 Precast Decks on PS Beams Samples of details included in the manual: Precast deck connections on concrete beams
15 Precast Decks on Steel Framing Samples of details included in the manual: Precast deck connections on steel beams
16 Precast DecksSamples of details included in the manual: Precast deck connections on steel beams
17 FRP DecksSamples of details included in the manual: FRP deck connections on steel beams
18 Total Bridge Element Prefabrication Everything shown in this graphic can be prefabricated and connectedEverything shown can be prefabricated
19 Complete Bridge Element Prefabrication New Hampshire ProjectHow fast can we build a bridge?Experimental projectAll components prefabricated115 foot spanPrecast cantilever abutmentsClock started after old bridge was removedRoadway open to traffic in 8 daysTime Lapse Video on YoutubeTMSearch “Epping Bridge Construction”This is an example of a totally prefabricated bridge in Epping, NH. All details used in this project are included in the manual.
20 Manual Distribution Availability Published June 2009 Is available through FHWA Highways for LIFE websiteThe manual is complete and available for use. A web-site is under development that will include the details in the manual. Other details will be added to the website as they become available.
21 Other Sources for Details Utah DOT ABC Website(search ABC)Piers, abutments, walls, decksPCI Northeast(Bridge resources)MassDOTWorking on new ABC manualNCHRP Report 681Development of a Precast Bent Cap System for Seismic RegionsWeb search “NCHRP Report 681”There are other sources of details for ABC connections.
22 Schematic Design of a Prefabricated Bridge This is an example of how to use the FHWA manual to prepare a structure type study for an ABC project.
23 Case Scenario 4 lane bridge over an expressway Existing bridge has deteriorated beyond repairHeavy traffic on both roadwaysA temporary bridge or staged construction is an optionThe local business will accept a short term closure with the detourAs opposed to a long term staged projectEstablish the detour and accelerate the bridge construction to less than 30 daysThis hypothetical bridge was chose to represent typical deficient highway overpasses throughout the country.
24 Existing BridgeThe existing bridge layout is as shown.
25 Existing bridge issues Leaking Deck JointsLow ClearanceMajor issues include deterioration of substructures caused by leaking joints and spray attack from passing vehicles. The clearance is also substandard.Salt spray attack from vehiclesSalt spray attack from vehicles
26 Proposed Bridge Type After a formal study, the owner opted for the following structure criteria:Continuous steel girders (weathering steel)Reduce to a two span bridgeIncrease clearance by raising approach grades (3’)Use integral abutments (no deck joints)Composite concrete deckMembrane waterproofing and Bituminous wearing surfaceOpen steel railings (galvanized)The proposed bridge is a conventional composite stringer bridge with the following criteria.
27 Proposed Bridge No Deck joints Move substructures away from roadway Build new piers and abutments in new locationsIncrease vertical clearanceThe layout was chosen to improve the geometry of the roadway under the bridge and eliminate the problems at the site. The new substructures are located at different location to facilitate construction. The new substructures can be built at the same time the existing substructures are demolished, thus saving time.
28 Sources of details - FHWA Connections manual: - NCHRP Report 681 “Connection Details for Prefabricated Bridge Elements and Systems”Review Chapter 1Investigate connection types, materials, tolerancesSearch applicable sections of other chapters for details- NCHRP Report 681“Development of a Precast Bent Cap System for Seismic Regions”- Utah DOT ABC StandardsBefore the connections are chosen form the manual. Designers should review chapter 1 to become familiar with ABC concepts.
29 Connection Types Chosen The owner chose the following connection typesGrouted reinforcing splice couplersQuick, proven systemCan develop full bar strengthSimplifies the design process (same as CIP)Grouted PT DuctsProvides significant adjustability at cap connectionGrouted VoidsCorrugated metal pipe voids for integral abutmentsSmall blockouts for pinned connections (approach slabs)Concrete Closure pours between precast elementsUse for a limited number of connections (slower)The design in this case chose three different types of connections for the bridge
30 Grouted Reinforcing Splice Couplers Emulates a reinforcing steel lap spliceMultiple companies – non-proprietaryUsed in precast parking garages, stadiums and bridgesInstallation video on youtubeSearch “Georgia Pier Construction”Grouted reinforcing splice couplers are an example of a connection that migrated from the vertical construction industry.
31 Grouted Reinforcing Splice Connectors The couplers can be used where ever a construction joint would normally be placed in a conventional bridge. This facilitates the design of the bridge because it can be designed as a cast-in-place structure. The couplers replace the normal lap splices. The only design change is the depth of the reinforcing cage in order to get proper cover over the couplers.
32 NCHRP Report 681 Detail Grouted PT Duct Similar to grouted sleeves Used in several statesTested for high seismic regionsSignificant adjustabilityDetails, specifications and design information availableThe NCHRP study was for high seismic regions, however the connections are good for all locations.
33 Footing to Sub-grade Connection The connection of the footings to the sub-grade is made with a simple grout pour. Flowable fill can also be used. The data sheet from the manual is shown.
34 Footing to Footing Connection Use CIP Closure PourCast closure pour during structure erectionDesign precast for structure DLDesign continuous footing for total loadsThe connection of the footings is a simple closure pour. The closure pour can be placed as the remainder of the bridge is erected. No need to wait for concrete to cure.
35 Footing to Column Connection The connection of the footings to the column is made with grouted couplers. The data sheet from the manual is shown.
36 Column to Cap Connection Use details from NCHRP Report 681The connection of the columns to the pier cap is made with grouted PT ducts.
37 Completed Pier Column to footing connection Column to cap connection Footing to footing connectionThis is a graphic showing the pier connections chosen.Footing to subgrade connection
38 Abutment Details Integral Abutment to piles Section Precast Integral Abutment to PilesCorrugated metal pipe voidsPlace over pile and fill with concreteDetail developed by Iowa DOTUsed in other states alsoReduces element weightHas large capacity totransfer pile loadsShear transfer via shear frictionCorrugated metal pipes are an inexpensive and structurally sound connection. The voids can be used to reduce element weight as well.
39 Abutment to Pile Connection The connection of the piles to the abutment cap is made with a simple grouted void. The data sheet from the manual is shown.
40 Abutment Cap to Cap Connection Use Utah DOT DetailsConcreted keyUse integral diaphragm to link caps togetherThe abutment cap to cap is made with a simple concreted shear key combined with the integral diaphragm that is case after the superstructure is in place. 2+ Piles per cap element are recommended.
41 Approach Slab Connection The connection of the approach slab to the abutment cap is made with a simple grouted void. The data sheet from the manual is shown. The connection of the backwall to the abutment stem is made with grouted couplers.
42 Completed Abutment Approach slab connection Cap to cap connection This is a graphic showing the abutment connections chosen.Pile to cap connection
43 Beam to Deck Connection The connection of the precast deck to the steel beam is made with a simple grouted void. The data sheet from the manual is shown. Note the age of this detail and its corresponding performance.
44 Deck to Deck Connections The connection of the precast deck to deck connection is made with a simple grouted key. The data sheet from the manual is shown. Note the age of this detail and its corresponding performance.
45 Deck to Deck Connections The transverse connection of the precast deck is completed with longitudinal PT. The data sheet from the manual is shown. Note the age of this detail and its corresponding performance.
46 Deck to Deck Connections A connection of the precast deck to deck is made with a closure pour at the roadway crown. This is done to reduce the handling size of the elements and account for the deck geometry. It is not required on every bridge. The data sheet from the manual is shown.
47 PC Deck Connection Details This is a graphic showing the deck connections chosen.
48 Superstructure to Abutment Connection Use CIP Closure PourUtah DOT DetailAllows for significant adjustabilityProvides connection between abutment stem elementsThis detail shows the integral abutment elements and connections. This detail is not included in the FHWA manual. It was taken from the Utah DOT ABC standards.
49 Completed Superstructure Longitudinal crown connectionCIP CurbConnection to beamTransverse slab connectionThis is a graphic showing the superstructure connections chosen.Longitudinal PTIntegral Abutment Connection
50 Complete Bridge Membrane waterproofing with bit. Wearing surface Precast full depth composite deckThis is a graphic showing the entire bridge.Precast Integral AbutmentPrecast Pier
51 Estimated Construction Schedule The schedule shown is based on real-world experience on ABC projects. This should be considered a minimum timeframe for a typical prefabricated element project.
52 Costs Typical New Bridge (Cost=$175/sf) = $2,200,000 Premium for ABC (assume 20%) = $440,000Temporary Bridge (Cost=$50/sf) = ($620,000)Net Savings = $180,000Note: These prices will vary greatly by regionThe costs shown are relative. ABC can cost more than conventional construction for the structural elements, however there are other non-structure savings that can be realized, including the cost of a temporary bridge.
53 Other Cost Savings Ways to reduce bid prices with ABC StandardizationProgrammatic (not one of a kind)Reduced project site costs (trailers, etc.)Reduced maintenance of traffic costsInflationOther Non- Bid Savings with ABCFewer police detailsReduced agency costs during construction (staff time)User CostsPlus: $$ can be significantMinus: $$ not in the budgetThere are other non-structure related cost savings that can also be realized.
54 QualityFL has had very good success with precast piers in very harsh environmentsCT has had Precast full depth decks in place for over 20 yearsCrack Free DeckExcellent conditionIntegral abutments eliminate deck jointsThe FHWA manual demonstrates that the details chosen can be exposed to harsh environments with great success.
55 You can only have any two Old AdageHigh QualityYou can only have any twoRapid ConstructionLow CostBased on the information discussed in this presentation, it is possible to get high quality, low overall project costs and rapid construction.By elimination of temporary bridges or costly stage construction schemes, and accounting for reduced agency costsyou CAN have all three
56 ConclusionsIt is possible to build a complete bridge in 30 days (or less)The FHWA manual provides a starting point for a complete bridge prefabrication projectNew details are coming on line all the timeNCHRP Report 681, Utah DOT, PCI Northeast (www.pcine.org)You do not need to sacrifice quality to get rapid constructionYou can save money on an accelerated bridge project by:Reducing construction timeEliminate temporary bridges or stagingIn conclusion: It is possible to replace a bridge in 30 days using prefabricated bridge elements. The FHWA manual is a great starting point for planning an ABC project. ABC does not necessarily mean higher overall project costs.
57 Module Conclusions You should now be able to: identify roadblocks to accelerated bridge constructionidentify the resources for locating Connection Details for PBESdescribe features of PBES that improve the quality of the finished productrecognize a typical construction schedule for a bridge built with PBESrecall ways to save money by using PBESYou should now be able to:identify roadblocks to accelerated bridge constructionidentify the resources contained in Connection Details for PBESdescribe features of PBES that improve the quality of the finished productrecognize a typical construction schedule for a bridge built with PBESrecall ways to save money by using PBES