Pile Design and Construction Practice, Fifth edition

Structural design of piles and pile groups 389

Minimum reinforcement

required by Code of

Practice

Load transferred

to piles over this

area

(^45) ̊
Figure 7.8Load transfer from column to deep four-pile cap.
bottom surface of the cap can be omitted. Also the sides and top surfaces of the cap may be
unreinforced if there is no risk of tension developing in these zones (see Figure 7.9). BS 8110
requires minimum percentages of reinforcing steel of 0.24 and 0.13 for mild and high tensile
steel respectively.
Pile caps constructed over large groups of piles as in Figures 7.10 and 7.11 can be
designed as solid slabs. The design requirements for these members are set out in Clause 9.3
of EC2.
45 °
≥50 mm
Compressed zone
Figure 7.9Distribution of compressive stress from pile head to pile cap.