Joint Transportation Research Program JTRP FHWA/IN/JTRP-99/3 Final Report EVALUATION OF STRAND TRANSFER AND DEVELOPMENT LENGTHS IN PRETENSIONED GIRDERS WITH SEMI-LIGHTWEIGHT CONCRETE Robert J. Peterman Julio A. Ramirez Jan Olek July 1999 Indiana Department of Transportation Purdue University Final Report FHWA/IN/JTRP-99/3 EVALUATION OF STRAND TRANSFER AND DEVELOPMENT LENGTHS rN PRETENSIONED GIRDERS WITH SEMI-LIGHTWEIGHT CONCRETE Robert J. Peterman, Kansas State University* A Julio Ramirez, Purdue University Jan Olek, Purdue University (formerly a Post-Doctoral Research Associate at Purdue University) Joint Highway Research Program Purdue University Project Number: C-36-56RR File Number: 7-4-43 Conducted in Cooperation with the Indiana Department ofTransportation and the Federal Highway Administration The contents ofthis report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the views or policies of the Federal Highway Administration and the Indiana Department ofTransportation. This report does not constitute a standard, specification, or regulation. Purdue University West Lafayette, EST 47907 July 1999 Digitized by the Internet Archive in 2011 with funding from LYRASIS members and Sloan Foundation; Indiana Department of Transportation http://www.archive.org/details/evaluationofstraOOpete TECHNICALREPORTSTANDARDTITLEPAGE 1. ReportNo. 2. GovernmentAccessionNo. 3.Recipient'sCatalogNo. FHWA7IN/JTRP-99/3 4.TitleandSubtitle 5. ReportDate July 1999 EvaluationOfStrandTransferAndDevelopmentLengthsInPretensionedGirders With Semi-Lightweight Concrete 6. PerformingOrganizationCode 7.Authors) 8. PerformingOrganization ReportNo. RobertJ.Peterman,JulioA. Ramirez,andJanOlek FHWATN/JTRP-99/3 9. PerformingOrganizationNameandAddress 10.WorkUnitNo. JointTransportationResearchProgram 1284CivilEngineeringBuilding PurdueUniversity WestLafayette,Indiana 47907-1284 11. ContractorGrantNo. SPR-2195 12. SponsoringAgencyNameandAddress 13. TypeofReportandPeriodCovered IndianaDepartmentofTransportation FinalReport StateOfficeBuilding 100North SenateAvenue Indianapolis,IN46204 14. SponsoringAgencyCode IS. SupplementaryNotes PreparedincooperationwiththeIndianaDepartmentofTransportationandFederalHighwayAdministration. 16. Abstract Indiana has been using lightweight aggregate consisting mostly of expanded shale in the production of prestressed concretebridgegirdersforseveralprojects. The lightweight aggregate hasbeen used aspartial replacement forregulargravel or crushedlimestonecoarse aggregate. Thissemi-lightweightconcreteweighsaround 2080 kg/m . Inastudy sponsoredbytheFHWA,thecurrentAASHTO equationsforthecalculationoftransferanddevelopmentlengthsof prestressing strandwerefoundtobeunconservativeinthecaseoflightweightconcretememberswithunitweightlessthan 1920 kg/m3 Thisfindingraisesaquestionregardingthe applicabilityofthesameequationsto semi-lightweightconcretemembers. . Theobjectiveofthis studyco-sponsoredbytheIndianaDepartmentofTransportation andtheFederalHighwayAdministration istodetermineifthecurrentAASHTO Specificationsare applicableto semi-lightweightpretensionedconcretebridgemembers. mm mm Thestudy addressesthetransferanddevelopmentlengthsof 13.3 and 15.2 pretensionedstrandinsemi-lightweight concrete girderswithconcretecompressivestrengthof48 MPaforthe 13.3 mmstrand and69MPaforthe 15.2 mmstrand. Two strandtypeswereconsideredinthisstudy. Theresultsofthelaboratoryevaluation suggestthatthecurrenttransferlengthof50 stranddiametersisadequateforsemi- lightweightconcreteiflongitudinal cracksarenotpresentalongthetransferlength. Inthepresenceoflongitudinalsplitting cracks,themeasuredtransferlength increasedtoapproximately70 stranddiameters. Itisrecommendedthatthecurrent requirementsforstranddevelopmentlengthbeenforced atadistance"dp"from thepointofmaximummomenttowardsthefree endofthestrand. Thequantity"dp" isthedistancefromtheextremecompressionfibertothecentroidoftheprestressingsteel butnotlessthan80% oftheoverallmemberheight, hithe specimenstested, web-shearcracks, interceptingthetransferlength nearthememberends,werenotpresent. 17. Keywords 18. DistributionStatement bond,concretebridges,developmentlength,prestressingstrand, NNaotiroensatrlicTteicohnsn.icTahliIsndfoorcmuamteinotnSiseravviaciel,ablSeprtiongtfhieelpdu,blVicAt2h2ro1u6g1hthe semi-lightweightconcrete. 19. SecurityClassif.(ofthisreport) 20. SecurityClassif.(ofthispage) 21.No.ofPages 22. Price Unclassified Unclassified 193 FormDOTF1700.7(8-69) ACKNOWLEDGMENTS Appreciation is expressed to the Indiana Department ofTransportation (INDOT) and the Federal Highway Administration (FHWA) for providing funding for this research. Specifically, INDOT personnel Tommy Nantung and Hasmukh Patel and FHWA personnel Tom Saad were key resource persons within these organizations. Also, the investigators would like to thank the personnel at CSR Hydro Conduit, Inc. for their support in meeting the difficult scheduling demands ofthis project. Specifically, the assistance given by William Yoder and Rick Yoder is especially appreciated. TABLE OF CONTENTS Page LIST OF TABLES iii LIST OF FIGURES iv IMPLEMENTATION SUGGESTIONS vi CHAPTER INTRODUCTION 1 1 1.1 Introduction and Background 1 1.2 Problem Statement 1 1.3 Scope 3 CHAPTER EXPERIMENTAL PROGRAM 2 4 2.1 Strand Validation (Moustafa Method) 4 2.2 Surface Condition Assessment 6 2.3 The Importance and Use ofTransfer Lengths and Development Lengths 6 2.4 Transfer-Length Measurements 10 2.5 Evaluation ofDevelopment Lengths 11 2.6 Calculation ofDevelopment Lengths for Test Specimens 12 2.7 Single-Strand Development-Length Specimens 14 2.8 Multiple-Strand Development-Length Specimens 17 2.9 The Importance ofStirrup Spacing on Longitudinal Steel Stress 20 2.10 Additional (3) T-Beams 23 CHAPTERS EXPERIMENTAL RESULTS 50 3.1 Pullout Tests 50 3.2 Surface Condition Assessment 53 3.3 Measurements ofTransfer Length 54 3.4 Results From Single-Strand Development-Length Tests 57 3.5 Results From Development-Length Tests on T-Beams 59 CHAPTER CONCLUSIONS AND RECOMMENDATIONS 4 4.1 Discussion ofResults 84 4.2 Conclusions 85 4.3 Recommendations 88 APPENDIX A APPENDIX B APPENDIX C APPENDIXD APPENDIXE LIST OF REFERENCES.