Point load on Water Tower Shell 2

[RFreund]

How would you determine the allowable point load on a water tower shell?

1.) Ask a manufacturer (do these exist?)
2.) FEA shell analysis or something along these lines?

Thanks in advance!

EIT

http://www.HowToEngineer.com

 

[dhengr]

Rfreund:
You’ve kept us guessing long enough, why not show us a sketch of the vessel and the actual loads, with some dimensions, etc. Otherwise, I’m guessing one billion tons on a 3/16" plate, 18' high and 200' in dia.

 

[BAretired]

I'm betting that one billion tons is a tad on the high side.

BA

 

[RFreund]

@TLHS - Thanks I really appreciate the info. I will look into the API 650 stuff.

@AMEC - I intend to or atleast try, however I'm not sure I have the software to do so accurately. Any idea on if RISA 3D could give me something reasonable? What program would you use?

DH- I hear ya. I don't mean to keep you guessing, but I don't have a specific project that this is currently applicable. I am anticipating that I will need something in the near future. I will however give some better info. Typically I'd say the point loads are in the range of 1kip - 3kip vertical reaction and 0.5k to 1.5k horizontal reaction. Usually the 'column / leg support' is an angle with a base plate about 10"x10"x1/2" maybe. As for the water tower the tower is usually 40'-80' in the air. Usually domed.

See attached crude sketch.


EIT
www.HowToEngineer.com

 

[JStephen]

API-650 doesn't have anything useful on point loads. It does have an Appendix P for nozzle loads, but it is restricted to flat-bottom tanks larger than 100' in diameter. (For simplicity, the pressure is assumed proportional to the shell thickness, which is not true for small tanks).

A suggestion on your arrangement: If you have multiple loads in a circular ring, then check total loading on the whole spherical cap of that radius rather than dealing with the point loads. If desired, you could add a circular stiffener around the base of the ring.

Normally, loads applied tangentially to a dome would have low streses and aren't really an issue.

Assuming this is antennas or something similar, you're also increasing the wind loading in the structure and foundation.