Guidance on the design of caps for groups of piles has been limited over the years. The Concrete Society published a two part article Standard Pile Caps, written by R Whittle of Ove Arup, in CONCRETE in January and February 1972.

The Institution of Structural Engineers has now published a Technical Guidance Note concerning the design of pile-caps for small groups of piles e.g. 2-4 piles. It relies on the strut and tie method to determine the amount of reinforcement required in the pile-cap; which is dependent upon the depth of the cap, the magnitude of the axial load being placed upon it, the cap’s concrete strength and the pile size and spacing.

The Institution of Structural Engineers. Technical Guidance Note: Designing a pile-cap, The structural Engineer, IStructE, vol 91, 2013