Design for bending (pile cap:ACI 318)
The pile cap is treated as a beam in bending, where the critical bending moments for the design for the bottom reinforcement are taken at the face of the column.
The basic design method is identical to that for beams - see:Design for bending for rectangular sections (concrete beam and slab: ACI 318)
Single pile pile caps
For single pile pile caps, the bending check is skipped by default in cases where the column is resting within the perimeter of the supporting pile, in a direct bearing situation.
The choice to perform the check or not (default) can be controlled via the "Ignore bending capacity checks for 1-pile pile caps" setting located in Design Settings > Concrete > Foundations > Isolated Foundations > General Parameters > Pile Cap > Design parameters.
In all cases where the column is not in direct bearing - i.e., eccentric with the pile, a warning is now provided in the results output stating that design assumes that the pile cap is stabilized by other means.
