Dissapating corner moments in a rectangular underground tank

In summary, the conversation discusses a project involving the replacement of a roof on a concrete tank at a river pump station. The tank is integral with three corners and has a unrestricted corner that is susceptible to large moments due to external factors. The solution proposed is to use corner struts to redirect the stresses, inspired by techniques used by cathedral builders and millwrights. Examples of masonry reinforcements, such as buttresses, are also mentioned.
  • #1
Infinitybyzero
33
3
This is a conceptual question based on a project I and a few other engineers finished at work. We are replacing the roof of a concrete tank that is part of a larger pump station for a river. Unfortunately, the roof is very integral in this structure, which means that once it's removed, the walls need to be braced.

The tank is roughly 60x20x22' deep and the long direction will have continuous shoring across mid height. The tank is integral on 3 corners with the rest of the station, but there is a corner that's unrestricted. From a theoretical standpoint, the soil, surcharge, and hydrostatic conditions on the outside of the walls cause a very large moment around that corner. The walls are close to 100 years old with no indication of corner steel/dowels, which obviously means that a large corner moment will crack the concrete quickly. There's no cracks in any of the tank right now and we certainly don't want to create any during construction.

Our solution was to provide corner struts to redirect some of the stresses, but realistically it won't go down that much because the walls are infinitely stiff compared to some 3" pipe. I'm not looking for a design recommendation, but more rather what you would do to dissipate excessive moment at the free standing corner of a tank (or wall intersection in a building) that is subject to significant lateral loading.
 
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  • #2
The great cathedral builders and the later millwrights knew all about this sort of problem .

Many problems were solved using buttresses and other masonary reinforcement .

For example :

Two buttresses one on each face near but not on corner . Plain taper or flying

Groin buttresses wrapped around corner .

Castellated corners .
 

Related to Dissapating corner moments in a rectangular underground tank

1. What are corner moments in a rectangular underground tank?

Corner moments refer to the forces and stresses that are created at the corners of a rectangular underground tank due to the weight of the soil and the contents of the tank.

2. Why is it important to dissipate corner moments in a rectangular underground tank?

If corner moments are not dissipated, they can cause the tank to deform or crack, leading to structural failure and potential leaks or spills. Dissipating corner moments helps to ensure the stability and integrity of the tank.

3. How can corner moments be dissipated in a rectangular underground tank?

Corner moments can be dissipated through the use of reinforcing materials such as steel bars or fibers, as well as properly designed and constructed tank walls and foundations. Other methods include adding additional support structures or using specialized tank designs.

4. Are there any regulations or standards for dissipating corner moments in rectangular underground tanks?

Yes, there are various regulations and standards that govern the design, construction, and maintenance of underground storage tanks, including guidelines for addressing corner moments. These regulations vary depending on location, so it is important to consult with local authorities and experts.

5. What are the consequences of not dissipating corner moments in a rectangular underground tank?

If corner moments are not properly dissipated, the tank may experience structural failure, leading to leaks or spills that can be harmful to the environment and costly to clean up. It can also result in damage to surrounding structures and pose a safety hazard to nearby buildings or infrastructure.

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