Flexural anchorage performance at diagonal crack locations.

PDFTech ReportFHWA-OR-RD-11-06SPR 661Reinforced concrete bridgesFlexural strengthBridge anchoragesCrackingOregonOregon. Dept. of Transportation. Research SectionHiggins, ChristopherTriska, Mary AnnGoodall, JoshuaOregon State University. School of Civil and Construction EngineeringOregon. Dept. of Transportation. Research SectionUnited States. Federal Highway AdministrationUS Transportation CollectionLarge numbers of reinforced concrete deck girder bridges that were constructed during the interstate system expansion of the 1950s have developed diagonal cracking in the stems. Though compliant with design codes when constructed, many of these bridges have flexural steel bars that were cut off short of the full length of the girders. When load-rating these structures, the current design specification check of tension reinforcement anchorage often controls the capacity of these bridges. The tensile force demand is controlled by the load-induced moment and shear, the number of stirrups, and the diagonal crack angle; however, little information is available regarding bond stresses developed with larger-diameter bars for full-size specimens in the presence of diagonal cracks.This research used large-size specimens to investigate the influence of diagonal cracks near flexural cutoff locations on the behavior and strength of vintage reinforced concrete girders. Testing indicated that a diagonal crack crossing the development length of cutoff longitudinal bars may not necessarily control specimen failure. Analysis showed that the required tensile demand at a diagonal crack location as predicted by AASHTO LRFD was reasonable. Two analytical methods and a non-linear finite element method were investigated for predicting the failure mode and capacity of the laboratory beams. A procedure was developed to rate existing bridges for flexural anchorage requirements around cutoff locations. Cracking characteristics indicative of flexural reinforcement slippage were defined for bridge inspection