Uplift , Counterbalancing Weight for API 650 Tanks

[abdelkarim10]

Dear All ,

I am designing some Storage Tanks as per API 650 I have some confusion regarding Uplift , Counterbalancing and Overturning moment
As my understanding

1)Uplift force calculated in order to know whether Anchor bolts is required or not
2)Counterbalancing Weight the weight to be given to civil to design the Tank Foundation
I appreciate if anyone can provide a clear clarification and any reference documents in order to understand

Thanks All

 

[bimr]

The uplift fore will most likely be caused by a wind load. Anchor bolts are generally installed regardless of the wind load.

The counterbalancing weight is most likely the weight of the tank contents.

Are you working off a data sheet? There are other factors to consider such as earthquake loadings.

Please consider posting enough information to understand the question. It makes a difference if this tank is 2,000 gallon capacity or 2 M gallon capacity.

 

[JStephen]

API-650 includes rules to determine if the tank needs anchorage or not. If this is the 2.5 psi tank from your other question, it will definitely be anchored.
Note that 2.5 psi in a large tank may give unreasonable requirements for the compression ring and the anchorage. For a 30' tank, no problem. For a 200' tank, you'd want to re-evaluate the pressure requirement.

What is needed for the foundation design is the pressure uplift forces, test pressure uplift forces, wind uplift, shear, and overturning moments, seismic shear and overturning moments, dead weight of the tank and how distributed, product weight, live/snow loads and how distributed, etc.
I believe API-650 uses the term "counterbalancing weight" to refer to the weight of the ringwall that is resisting uplift.

 

[abdelkarim10]

I think all of you for this response