Manning's roughness coefficient for buried composite arch bridges.

Details

• Creators:
  Yang, Lingqiang ; Zou, Qingping
• Corporate Creators:
  University of Maine. Advanced Structures and Composites Center
• Subject/TRT Terms:
  • Arch bridges
  • Fiber reinforced polymers
  • Tubing
  • Streamflow
  • Roughness coefficient
  • Hydraulics
  • Flow measurement
  • Concrete
• Publication/ Report Number:
  ME 14-15
• Resource Type:
  Tech Report
• Geographical Coverage:
  Maine
• Corporate Publisher:
  Maine. Dept. of Transportation
• Abstract:
  This report includes fulfillment of Task 9 of a multi-task contract to further enhance concrete filled FRP tubes, or ; the Bridge in a Backpack. Task 9 investigates the interaction of water flow under the bridge with the tubes and ; decking and recommends Manning’s roughness coefficients for water flow under the composite backpack bridge ; system. ; There are three flow regimes and each has a different resistance relationship. Quasi-smooth flow occurs only when ; there are depressions or when roughness elements are spaced very close. Hyper-turbulent flow occurs when ; roughness elements are sufficiently close so each element is in the wake of the previous element and rough surface ; vortices are the primary source of the overall friction drag. Isolated roughness flow occurs when roughness spacing ; is large and overall resistance is due to drag on the decking surface and form drag on the arches. Due to the large ; sizes of the tubes and tube spacing, the conventional method of computing roughness coefficient using the formula ; for rough pipe is not applicable here. Instead, we have to use a more complex procedure to calculate the roughness ; coefficient using different formula for different flow regimes described above. ; In this report, Manning’s roughness coefficients are provided when the flow is perpendicular to the bridge and when ; the angle between flow and the bridge is 45 and 30 degrees (Appendix 1). Depending on the arch radius and tube ; size and spacing, Manning’s roughness coefficient of the bridge ranges from 0.016 to 0.045, which is significantly ; larger than that for smooth concrete (n=0.012), due to the large tubes underneath the bridge. These results are ; important findings and should be incorporated in a hydraulic model such as HECRAS to more accurately predict ; water flows and backwater profiles at the FRP tubular bridge.
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• Format:
  PDF
• Funding:
  20111223*2878
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28488/dot_28488_DS1.pdf
• File Type:
  [PDF - 3.44 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:965725a210264ef0cf5233c14186dc75c364d3341e345dbb9510648af8bbd4fc