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1D Bridges: Difference between revisions

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Peir loss coefficients are treated as a direct energy (form) loss and can be derived from information in publications such as ''Hydraulics of Bridge Waterways'' ([http://www.ciccp.es/ImgWeb/Castilla%20y%20Leon/Documentaci%C3%B3n%20T%C3%A9cnica/Hydraulics%20of%20Bridge%20Waterways%20(1978).pdf FHA, 1978] or [https://austroads.com.au/publications/bridges/agbt08 AUSTROADS, 2019]).
 
Energy loss estimates from bridge piers or other obstructions, vertical or horizontal, that do not cause upstream controlled flow regimes like pressure flow, are dependent on the ratio of the obstruction's area relativeperpendicular to the flow direction to the gross flow area of the bridge opening, the typeshape of the piers (or piling in the case of pile bents)obstruction, and the angularity of the piers/obstruction withto the flow direction. ofFor flood flow.example, Theusing FHA (1978) guidancethe advisesapproach what form loss coefficient should be adopted based on these input parameters.is:
<ol>
<li>Calculate the ratio of the water area occupied by piers to the gross water area of the constriction (both based on the normal water surface) and the angularity of the piers. These inputs are used to calculate "J" in the FHA documentation.</li>
<li>Use the FHA (1978) ''Incremental Backwater Coefficient for Piers'' data to calculate Kp. This is the value whichthat will be entered into TUFLOWthe bridge's LC (loss vs height) table as the energy or form loss coefficient. For piers or obstructions that are non-uniform in dimensions or shape the LC table can be used to vary the losses with height accordingly noting that losses will need to be proportioned with depth to reflect the combined effect of the different obstruction shapes/dimensions.<br>
[[File:FHA_Kp_arrow.PNG|400px]]
</li>
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