Water reservoir design actions 2

[Jackoe]

I am in the stages of designing a water reservoir. With static backfill pressures how do I find the vertical, horizontal bending moments and shears in the concrete wall?The reservoir is not being stressed. The wall in effect will act as a retaining wall and will be full fixed into the foundation. Is there any literature which will help me find the actions in the wall when I know the pressures in the wall. Even something that would tell me the percentage of load converted to membrane shear and bending moment.

Any help would be appreciated

 

[JedClampett]

You need a soils (Geotechnical) report to give you the active, at-rest and surcharge soil pressures. If the wall is a cantilever you'll use the active pressure with the appropriate surcharge and if the wall is a propped cantilever you use the at-rest pressure and surcharge.
The forces you need to worry about are bending and shear, particularly at the base. If these terms don't mean anything to you, you need to get a structural engineer.

 

[rapt]

You still have to worry about ring tension as you move up from the base also.

 

[Jackoe]

Thanks Jed

However what I am looking for is how a circular reservoir actually resists these loads that are applied to the face of it. I am using an active pressure as the top of the reservoir wall can move. What I am saying is the circular wall should more efficently disrtibute the loads throughout it better than say a long straight wall. I could design it for this however I feel it will be far too conservative. Surely more than 50 % of the load will be resisted by membrane shear in the reservoir wall.

 

[JStephen]

Once upon a time, I remember actually seeing a book in the Texas Tech library on the topic.

First question, which you answered in your second post, is whether the tank is circular.

Not sure it will specifically answer your question, but check "Theory of Plates and Shells" by Timoshenko, or other shell analysis books, which have a lot of general information on design of cylindrical shells. "Formulas for Stress and Strain" has a certain amount of information on cylindrical shells.

If you haven't done so, check the different industry codes- AWWA, ACI- they may shed some light on the problem even if not specifically applicable to your situation.

 

[JedClampett]

The best publication for your design is "Circular Tanks without Prestressing" by PCA,

http://www.cement.org/bookstore/profile.asp?store=&pagenum=1&pos=0&catID=&id=218.

It will hopefully answer your questions.