Can you give a little more info on what you are trying to do here? For example, are you trying to get a single point reaction for design? Or design for punching shear on the slab/mat above the pier cap trying to optimize pier dimensions? Or reinforcement? What design code/standard?
I am trying to design the pier cap for both flexure and shear. The cap is subjected to point loads. I know what dimensions I want, I just need to get the flexural and shear reinforcement. I'm using ACI 318-05. Thanks for your help.
I would model it with shell type area finite elements and mesh at pier and column locations. Use springs or restraints at pier locations. Use of the section cut is useful to obtain integrated shears and moments.
