Water tanks effects on structural response?

[wardak21]

Hi,
I am going to design a high rise building (16 story) and have to think of water supply as well.
I like to put the Water Tank on the top of the building. Can anyone advice me to do this or not?, what would be its effects (good or bad) on the structural response for lateral loads?
Is there any other best option to look into?

regards

 

[TERIO]

Chapter 6 and appendix F of the linked document may be helpful in developing loads.

http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=4620608

 

[Ron]

I can think of a variety of reasons not to do this...

First, your entire structural cost will be increased because of the increased loading (vertical and lateral) that will be carried all the way to the foundation....why do that?

If you are in a seismic area, it will change the entire response spectrum of your building during a seismic event...the tail will be wagging the dog.

A water storage tank has to be maintained. It is difficult to maintain ANYTHING placed on a roof (difficult access, increased cost of repair, damage to roof membrane system....)

Unless you plan to construct the tank in-place, you will have to use a larger crane to get it on the roof than you would need for construction of the building. Again...increased cost and difficulty.

You will have other equipment on the roof that is necessary for the function of the building, yet the tank will take up a lot of roof area....you might not have enough room for all.

I'm sure if I thought about it a little more I could come up with a few more reasons not to do this.

I see no benefit to putting the tank on the roof, but I see a lot of difficulty and cost.

 

[Teguci]

Best option - Install a pool instead!

I am currently muddling my way through the AWWA D100 seismic calculation for steel tanks and the only thing that seems tricky is the sloshing effect of the contained liquid.

ASCE 7 has a section on convective forces(aka sloshing for people that want to be understood) -section 15.7

 

[MiketheEngineer]

Pumps are often used to carry the water up. And flushing a toilet from 16 stories also has its problems!!! Check with a plumbing engineer or go to their website - plumbingeng.com

They have many articles on this subject.

 

[wardak21]

Thanks to all,
Dear Ron, I am thinking about the cost and structural response especially due to lateral load; BUT erection of a water tank will also cost much or equal to this.
And as MiketheEngineer said, using pump will be an option.

Dear Teguci, the building is in a moderate seismic region, I hope I could understand the ASCE 7 (sec-15.7) for sloshing effects of pool (water tank).

Thanks

 

[JStephen]

I would suggest having the water system design roughed out so you know what to expect on the structural aspects.

Water tanks on roofs are pretty common on old buildings, but I don't recall ever seeing one built on a newer building. Go to Google image search, put in "rooftop water tank" and it'll pull a bunch of pictures up. Most of them look like they're 50+ years old, too.