Thank you very much. Just what I was looking for. Any suggestions on steel orientation in the cap under a single pile. Calculated the required are for punching shear. Need to figure out orientation. Just a mat at the bottom surface ...
JP - Suggest that your punching shear calcs be based on plain (unreinforced) concrete strength. Then, add a rebar cage that includes both top and bottom mats.
This is one of those times when there is no point in "skimping" on reinforcement, regardless of what the calculations show. The differential cost of a significant rebar cage is trivial compared to the cost of associated pile driving, concrete forming & placement.