concrete tank with large openings
concrete tank with large openings
(OP)
Hey all - I'm designing a concrete vault for some water lines(it will be empty except for the lines running through). The tentative dimensions will be 6' wide x 20' long and approx. 12' high. The top of the tank will be flush with the ground with some hatches for access. I'm planning to use the PCA publication for Rectangular Concrete Tanks but I'm concerned about the large water line openings. There will be a 42" dia. pipe running through each of the short ends... possibly the other direction as well but don't know yet. What is the general consensus on designing for these openings? There aren't any provisions in the PCA book about openings. I wouldn't be concerned if they were small openings but 42" seems large.
Thanks,
JAH
Thanks,
JAH






RE: concrete tank with large openings
Be sure to check buoyancy, don't want this thing floating out of the ground. Also, if this is near the coast you need to consider sand and water above the tank. We had to design one for 10 feet of saturated sand on top of the top slab. Top slab ended up being 24" thick due to the span.
RE: concrete tank with large openings
RE: concrete tank with large openings
RE: concrete tank with large openings
RE: concrete tank with large openings
RE: concrete tank with large openings
RE: concrete tank with large openings
For small openings at the base you can cut and add reinforcement as standard. However,you have to be carefull if the openings is near the base are large in relation to the wall. If the width of openinings is a large percentage of the lenght of the wall, then you are cutting of the support provided by the base and then I would design the wall as spanning one way between the side support with the loading taken at the center of the pipes.
I do not khow of any guidance anyware. You just have to make your own assessment.
As a note. With tanks below or above ground, i always design the wall as free at the top. If you allow for a pinned or fixed connection to the roof, chances are good the the contractor will want to backfill or hydro test the structure before adding the roof and you will be ask to check and possibly redesign the walls.
Cheers
HvZ
RE: concrete tank with large openings
For a tank with those dimensions, the forces in the end walls will be heavily influenced by the long side walls. I would expect high bending moments about the vertical axis for the entire six foot width of the wall.
RE: concrete tank with large openings