Easy way to find Pier Pad Capacity

[sach4u1]

Hi all, I have a pier that has been modified. A square concrete cap was added to the top of the pier to take additional moment. The pier is 6' in dia. The concrete cap size is 20' square. What is the easiest way to find out the moment taken by the concrete cap? I know the lengthy procedure from books. I need a very quick check or calc. Thank you.

 

[apsix]

The moment capacity would be limited by the pier capacity, I can't see how an over-sized cap would increase the capacity.
Of course, a sketch would clarify the problem.