ground supported storage tanks for liquids
ground supported storage tanks for liquids
(OP)
Hello all....I have a water storage tank that I am only providing the foundation design for. 32' tall x 10.5' dia. Looking at 15.7.6.1 of the ASCE 05, I can calculate the base shear V by using method (a), 15.4.2, where V = 0.3SdsWI. If I use this equation to calculate my shear, do I need to add the Vi and Vc for impulsive and convective (sloshing) components? If so, do I all this to my V from 15.4.2? And, how to calculate Wi and Wc?
Once I get my base shear, would I apply this at the center of mass to calculate my overturning moment?
Thanks!
Once I get my base shear, would I apply this at the center of mass to calculate my overturning moment?
Thanks!






RE: ground supported storage tanks for liquids
Don't be surprised if your base shear changes from the ASCE method.
RE: ground supported storage tanks for liquids
AWWA is the typical go-to standard for steel tanks for water storage. They give very specific guidance on calculating lateral atmospheric loads and anchoring. However, if you aren't the tank designer you'll probably end up guessing on some of the variables you'll need to calculate all of that.
RE: ground supported storage tanks for liquids
RE: ground supported storage tanks for liquids
RE: ground supported storage tanks for liquids
RE: ground supported storage tanks for liquids
If not and the owner approves the change then using AWWA D100 calculate reactions keeping track of your assumptions (such as TCL = top capacity level, MOL = max operating level, shell thickness, roof weight, floor thickness) and add ~15% to account for inaccuracies in your assumptions. Then provide all of these calculated reactions and assumptions on your drawing cover page.
Technically, to calculate seismic shear and overturning moment per AWWA D100:
V = sqrt{ [Ai x (Ws + Wr + Wf + Wi)]^2 + [Ac x Wc]^2 }
where A = design accelerations, W = weights, i = impulsive, c = convective, and s,r,f = shell, roof, and floor
The moment calculation adds in Xs, Hr, Ximf, and Xcmf for the respective heights of force centroids for each of the above components, minus the floor which shouldn't add any moment (at least at the top face of your foundation). Calculating Wi, Wc, Ximf and Xcmf is a bit daunting, with hyperbolic trig functions as JedClampett described.