How Do I Determine the Force of Flowing Water

[PBW2]

I need to analyze a pipe hanger that will be located along the bottom of a bridge. I need to determine what force the river flow will have on the pipe during a flood. I've been told to use 3 fps as the velocity of flow.

The pipe is 8" and carries water. I've been racking my brain but can't seem to find the correct formula.

Thanks for any help.

 

[gbam]

Grab your old hydraulics book and look through the momentum equation, etc... You may have to derive the procedure inorder to fully understand it.

 

[LHA]

Momentum will give you a force at various points. You will then have to analyze torque/moment and compare to pipe material specs.

But first, work on that velocity...use a flow versus cross sectional area analysis. For that you will need depth. For that, Manning's on the section might do, but I would do a HECRAS run on it. During your design flood, the water most likely will greatly exceed 3 fps. That is the most important prerequisite. I don't think you should seal your conclusions without a better velocity.

 

[dicksewerrat]

What about ice floes? They have ripped more stuff from under bridges than just water. They bring an impact, point load to the party. Then think about debris.

 

[cvg]

not just ice, how about other floating debris such as trees?

 

[PBW2]

Thanks for the response.