Finite element analysis of deep wide-flanged pre-stressed girders : draft final report

794229563Covered final report; 2009-2011.PDFTech ReportWHRP 11-06WisDOT SPR# 0092-10-12GirdersConcrete bridgesPrestressed concrete bridgesPrestressed concreteCrackingTestingWisconsinWisconsin Highway Research ProgramOliva, Michael G.Okumus, PinarUniversity of Wisconsin--Madison. Dept. of Civil and Environmental EngineeringWisconsin. Dept. of Transportation. Research Coordination SectionNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresUS Transportation CollectionHundreds of prestressed concrete girders are used each year for building bridges in Wisconsin.The prestress transfer from the prestressing strands to concrete takes place at the girder ends.Characteristic cracks form in this end region during or immediately after detensioning. Potential solutions tocontrol end cracking were examined via finite element models and the impact of each solution on crackingwas evaluated. Modifications to reinforcement bar size, debonding ratios, strand cutting sequence and useof draped strand patterns were simulated by the models. The results from different analyses were comparedto quantify the success of each method in reducing strains causing girder end cracks. The tension strainsleading to cracks of all types were responsive to debonding some of the bottom flange prestressing strands.Bottom flange cracking can be prevented by methodically debonding exterior strands, keeping the drapedstrands bonded, and evenly distributing the remaining bonded strands over the bottom flange