You can definitely model that in Robot. If your main goal is the reactions at the piles/supports, then you could simply use a panel element for the pile cap and model the piles AND piers as penetrations all linked with rigid links and respective support & load conditions.
See the video in the link below, its a step by step approach of exactly what you are after I think. Note, the video only shows the results in the panel (pile cap) but you can easily check the reaction at the nodes on the piles too.
