End region detailing of pretensioned concrete bridge girders.

PDFTech Reporthttp://ntl.bts.gov/lib/47000/47400/47429/FDOT-BDK75-977-05-rpt-A.pdfhttp://ntl.bts.gov/lib/47000/47400/47430/FDOT-BDK75-977-05-rpt-B.pdfhttp://ntl.bts.gov/lib/47000/47400/47431/FDOT-BDK75-977-05-rpt-C.pdfhttp://ntl.bts.gov/lib/47000/47400/47432/FDOT-BDK75-977-05-rpt-D.pdfhttp://ntl.bts.gov/lib/47000/47400/47433/FDOT-BDK75-977-05-rpt-E.pdfhttp://ntl.bts.gov/lib/47000/47400/47434/FDOT-BDK75-977-05-rpt-F.pdfhttp://ntl.bts.gov/lib/47000/47400/47435/FDOT-BDK75-977-05-rpt-G.pdfhttp://ntl.bts.gov/lib/47000/47400/47436/FDOT-BDK75-977-05-rpt-H.pdfUF Project No. 00072910UF Project No. 00074016BDK75 977-05Prestressed concreteGirdersServiceabilityBridge designPretensioningShear strengthReinforcement (Engineering)Load testsFinite element methodFloridaFlorida. Dept. of TransportationHamilton, H.R.Consolazio, Gary R.Ross, Brandon E.University of Florida. Dept. of Civil and Coastal EngineeringNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresNTL-HIGHWAY/ROAD TRANSPORTATION-DesignNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionEnd region detailing has significant effect on the serviceability, behavior, and capacity of pretensioned concrete girders.In this project, experimental and analytical research programs were conducted to evaluate and quantify the effects ofdifferent end region detailing schemes. Two end region design models were developed using results from the experimentaland analytical programs. The first model can be used to design confinement reinforcement to prevent lateral-splitting failureat ultimate strength. The second model focuses on serviceability criteria and can be used to calculate bottom flange stressesdue to prestressing and thereby assess the likelihood of bottom flange cracking in the end region.The experimental program was conducted using (14) Florida I-Beam (FIB) specimens. Cracking and strain data werecollected during prestress transfer and during the months following transfer. These data were used to evaluate serviceabilitycriteria. Following serviceability evaluations, specimens were load tested to determine capacity and behavior due to appliedloads. Specimens were loaded in three-point bending at a shear-span-to-depth (a/d) ratio of approximately 2.0. Variablesconsidered in the experimental work included confinement reinforcement, steel bearing plates, horizontal reinforcement,vertical reinforcement, strand quantity, strand shielding, and strand layout.The analytical program was conducted using finite element analysis (FEA). FEA models were validated using data fromthe experimental program. Variables considered in the analytical program included bearing pad geometry, bearing padstiffness, steel bearing plates, transfer length, and prestress release sequence.A test program was also conducted to evaluate the shear strength of 1950s era pretension girders used in the Floridahighway system. These girders are of interest because they have thin 4 in. webs and very little specified shearreinforcement. Six test girders were removed from an existing bridge and were tested to failure in the laboratory. Resultsfrom the testing will be useful in determining the shear strength of similar pretensioned girders.Recommendations are provided with regard to detailing of confinement reinforcement, embedded bearing plates, strandshielding, and crack control. Recommendations are also given regarding evaluation of early pretensioned girders