Factor of Safety for Overhead Water Tank

[MechEChad]

I have been tasked with installing a 500Gal water tank about 8 feet in the air. The thing is that the only place we have to install it is right above a common walk way. I am in the process of designing the framework to support this, but where I am not sure is what factor of safety I should strive for with this framework. I was thinking that a minimum of 5 would be good since people will often be around/under this tank. Any recommendations are appreciated.

Thanks,

 

[BAretired]

As there is no vibration associated with a water tank, the supporting structure could be designed using normal safety factors as stipulated in the code. A safety factor of 5 is a bit of overkill, but for such a small tank, go for it.

BA

 

[ST04]

It is small tank and close to the ground.
But since it is only (1) tank, using such factor of safety won't be a problem.
good luck

 

[MiketheEngineer]

With that factor of Safety - I don't think seismic or wind would come into play. But you might check.

 

[MechEChad]

BA - When you mention "normal safety factors as stipulated in the code" to which code are you referring?

It is actually wind that I am the most concerned about. This is quite a bit of weight at a relatively high center of gravity. I am afraid once it starts to slosh we will have a vibration situation and could then have larger issues on our hands.

Thanks for the replies.

 

[BAretired]

In my case, I would use the Alberta Building Code which closely parallels the National Building Code of Canada. In your case you would use the building code recognized by the state the structure is in.

If you have high winds in your area, the support structure will need to be designed to prevent "sloshing". If you have seismic activity in your area, your building code gives adequate design criteria to design for that.

I do not oppose using a slightly higher safety factor than usual because the cost is pretty small but a factor of 5 seems a bit conservative.

BA