Full Scale Testing Of Overhang Falsework Hangers On NCDOT Modified Bulb Tee (MBT) Girders

Today’s bridges are being constructed with longer spans and higher girder spacing. As a result, the use of precast prestressed concrete modified bulb tee (MBT) girders has significantly increased. The MBT girders have a wider and thinner top flange than other conventional precast concrete cross-sections. The strength of the thin top flange has been identified as a concern for the North Carolina Department of Transportation when edge of flange falsework hangers are used to support the overhang deck slab falsework system. In response to theses concerns, the NCDOT has funded research project number 2005-18 “Full Scale Testing of Overhang Falsework Hangers on NCDOT Modified Bulb Tee (MBT) Girders” to study the behavior of the edge of flange falsework hanger systems. This research includes full scale testing of standard falsework hangers manufactured by Dayton/Richmond and Meadow/Burke installed on an NCDOT MBT girder and an analytical investigation that utilized three dimensional finite element modeling. The effects of the girder shear reinforcement, interaction with adjacent loaded hangers, and the type of hanger were included in the experimental and analytical investigations. The finite element modeling was used to predict the response of the falsework hanger system. It was concluded that the shear reinforcement, number of loaded hanger and the type of hanger affect the ultimate strength and behavior of hanger system. The observed ultimate strength of the Dayton/Richmond hangers was higher than the observed ultimate strength of the Meadow/Burke hangers. However, in all cases the observed ultimate loads were less than the manufacturer’s specified ultimate strength. It was recommended that the safe working load of the Dayton/Richmond and Meadow/Burke falsework hanger embedded on the NCDOT modified bulb tee (MBT) girder be reduced, and that the use of different type of overhang hanger system such as through flange hanger appears to be necessary to support a 6,000 lb. safe working load (12,000 lb. ultimate).

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 245p

Subject/Index Terms

Filing Info

  • Accession Number: 01152601
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/NC/2006-12
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Mar 1 2010 2:43PM