It usually forms part of the foundation of a building, typically a multi-story building, structure or support base for heavy equipment. The cast concrete pile cap distributes the load of the building into the piles. A similar structure to a pile cap is a “raft”, which is a concrete foundation floor resting directly onto soft soil which may be liable to subsidence.
As per IS 2911 (Part I/ Sec 3) -2010, the pile cap may be designed by assuming
that the load from column is dispersed at 45° from the top of the cap up to the mid
depth of the pile cap from the base of the column or pedestal. The reaction from
piles may also be taken to be distributed at 45° from the edge of the pile, up to the
mid depth of the pile cap. On this basis the maximum bending moment and shear
forces should be worked out at critical sections.
(i) Pile cap is perfectly rigid.
(ii) Pile heads are hinged to the pile cap and hence no bending moment is
transmitted to piles from pile caps.
(iii) Since the piles are short and elastic columns, the deformations and stress distribution are planer.
See More ONE WAY AND TWO WAY SLAB DESIGN PROGRAMME
(i) Shape of pile cap.
(ii) Depth of pile cap.
(iii) Amount of steel to be provided.
(iv) Arrangement of reinforcement.
DETERMINE NUMBER OF PILE
PILE CAP ARRANGEMENT AND PLANE DIMENSION
PILE CAP PRELIMINARY DEPTH
CHECK FORCES IN PILES
CHECK FOR PUNCHING SHEAR
CHECK FOR SHEAR
DESIGN OF MOMENT
CHECK FOR BOND
DETAILS FOR REINFORCEMENT