Pile Cap Design Spreadsheets to Eurocode 2 (EN 1992-1: 2004)

A pile cap is defined as a concrete block cast on the head of a group of piles, to transmit the load from the structure to the group of piles. Generally, pile cap transfers the load form the structures to a pile group, then the load further transfers to firm soil.External pressures on a pile are likely to be greatest near the ground surface. Ground stability increases with depth and pressure. The top of the pile therefore, is more vulnerable to movement and stress than the base of the pile. Pile caps are thus incorporated in order to tie the pile heads together so that individual pile movement and settlement is greatly reduced. Thus stability of the pile group is greatly increased.The functions of a pile cap are,

  1. To distribute a single load equally over the pile group and thus over a greater area of bearing potential,
  2. To laterally stabilise individual piles thus increasing overall stability of the group. And
  3. To provide the necessary combined resistance to stresses set up by the superstructure and/or ground movement.

Pile Cap Arrangement

  • Spacing of the piles in the pile group

The following should be considered when determining the spacing of the piles:

  1. Overall cost of the foundation
  2. Nature of the ground
  3. Pile behaviour in the group
  4. Resulting possible heave or compaction of ground causing damage to adjacent structures
  5. Cost of pile cap
  6. Size and effective length of ground beam
  7. Type and size of pile

Piles should be placed in a suitable arrangement so that the spacing between piles ranges from (2-3) D (pile diameter) in case of isolated pile caps and (2-6) D in case of rafts supported on piles.

  • The C.G. of piles should be placed as far as possible in the C.G. of loadstransmitted from the structure to the group of piles.
  • In the case of presence of neighbors, piles should be away from the property line by a distance not less than D or as the pile installation method requires.
  • The projection of the pile cap should be 10-15 cm.

Pile Cap Design Spreadsheets to Eurocode 2 (EN 1992-1: 2004)

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