As a_urbs noted the lack of confinement is allowing the spalling. The attached shows a method I've used to provide post-tensioned confinement. In your case, due to the size of the column, extra confinment could be provided with threaded rod through the column, located midway to each face...
Dig a 600 deep hole to determine the soil at that depth.
If it's fill (made ground) it's not deep enough.
If it's very dense gravel it's all good; show the structural engineer for signoff.
sdz, my AS1170.0 Table F2 for wind has ARI = 500 years. Do you have the latest version? Mine includes Amendment 5, issued in 2011.
Since there is no tank floor it looks like tiedown is required.
Strict interpretation could mean that interpolation shouldn't be done in that case, but I DO use 0.0 to interpolate. This would seem to agree with the logic of the rule.
The BAR is actually defined as the average roof height (h) divided by the smaller of b or d, ie the smaller plan dimension.
The reference number on the diagram is a representative location for the associated Kl. There are multiple elements with multiple factors, but they are assessed in...
A generously sized fillet at the wall-slab junction will help detailing of the joint.
16" doesn't seem overly generous if the wall is cantilevering, hopefully it can also span horizontally.
As AS 1597.2-2013 is for spans exceeding 1200mm, the effective width of 1.22m would not be appropriate for spans less than this.
The serviceability limit state ew = 0.5 + 0.3L would be more appropriate.
