Precast alternative for flat slab bridges : final report.

Details

• Creators:
  Nielson, Bryant G. ; Schiff, Scott D. ; Pang, Weichiang ; Sheng, Huan
• Corporate Creators:
  Clemson University. Glenn Department of Civil Engineering
• Corporate Contributors:
  South Carolina. Dept. of Transportation ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Alternatives analysis
  • Beams
  • Bridge construction
  • Bridge design
  • High performance concrete
  • Longitudinal cracking
  • Precast concrete
  • Surveys Precast bridge joint
  • hollow-core bridge
  • NEXT D bridge
  More +
• Publication/ Report Number:
  FHWA-SC-13-04
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States;South Carolina
• Edition:
  Final report
• Corporate Publisher:
  Clemson University. Glenn Department of Civil Engineering
• Abstract:
  The cast-in-place (CIP) concrete slab bridge and the hollow core flat slab bridge are two very common bridge types utilized by the ; South Carolina Department of Transportation (SCDOT). The CIP bridge is durable but has a long construction time while the hollowcore ; bridge has a short construction time but produces durability concerns. Trying to balance the speed of construction for hollow-core ; and the durability of CIP, the SCDOT commissioned this study to provide a recommendation for an alternative bridge type that could: ; 1) eliminate or minimize longitudinal cracking, 2) have a shorter erection time than the CIP flat slab system, and 3) have no restriction ; on ADTT and can be used on the National Highway System. ; There were two distinct phases in this research. In Phase 1, a thorough online survey and telephone interviews were conducted to ; investigate the pros and cons of existing short-span bridge systems used by other state departments of transportation. In addition, ; feedback from contractors and precast element fabricators in the Southeast region was also solicited. Based on this work, a precast ; bridge system known as the NEXT-D (Northeast Extreme Tee) beam was selected by the SCDOT for further testing and validation. ; The experimental and analytical validation along with the design of a 6 ft. wide section (NEXT-6) and an 8 ft. wide section (NEXT-8), ; with span lengths from 22 ft. to 40 ft., was the focus of Phase 2. ; The results of the experimental study indicated that U-shaped reinforcing bars and poly-vinyl alcohol (PVA) fiber reinforced ultrahigh ; performance concrete (UHPC) were an effective combination when used for the shear key located between precast NEXT ; elements. These results were also used to calibrate analytical models which were used to better understand and quantify the load ; demands associated with this beam type. Using this new understanding, a set of new design guidelines for the new NEXT-6 and ; NEXT-8 bridge systems was developed. For the beam design, the AASHTO live load distribution factors for tee beams are ; recommended to be used. For the deck design, the AASTHO strip method is recommended with some modification. A simplified fourstep ; procedure was developed to assist bridge engineers in determining the design demands (positive and negative moments) on a onefoot ; strip of deck for Strength I and Service I limit states. ; The results of this study, field experience with existing cast-in-place and precast bridges and sound engineering judgment allow the ; investigators to believe with a reasonable degree of confidence that the construction of a bridge using the provided recommendations ; and new system will lead to durable bridges that are cost effective and can be constructed using an accelerated schedule. One of the ; immediate needs is to now share the results of this study with neighboring states, so that the investment of needed steel forms by ; precasters can result in similar precast pieces sold to multiple states.
  More +
• Format:
  PDF
• Funding:
  SPR 682
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/31097/dot_31097_DS1.pdf
• File Type:
  [PDF - 26.89 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:64f10bbad838988d2bc7ee16575f668a51c43916236ea09345f06261765fe1820a5da9675f34904938a6976247f54ff446b0828edd417c84d8d7ec9811851e64