Bracing on flat head of horizontal tank

[beatrice82]

I have an existing water tank 144" diam with bracing spaced every 24". Using UL 142 13.3.3 and table 13.2 as a reference this tank would only need 1 brace 6" below the center of the head. Was the bracing on the head of the water tank overdesigned or am I reading Ul 142 wrong?

 

[JStephen]

It's probably overdesigned to some extent. There's not any code or standard that says how that ought to be done, and if you're not following UL 142 or something, you'll probably be designing the plate as beam sections, rather than a 2-way plate, which is conservative.

For a one-off design, it may be quicker to weld the extra stiffeners on than it is to show you don't need them.