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Design of Pile Cap

A pile cap is basically a broad concrete mat that lies on concrete or timber piles that have been directed into the unsteady or soft ground to offer an appropriate robust foundation. Furthermore, it generally creates component of a building’s foundation, usually a multi-storey structure, structure or supporting ground for weighty equipment. Moreover, the cast concrete pile cap spreads the structure’s load into the piles.

An analogous structure towards a pile cap is a ‘raft’, that is a concrete foundation floor lying plainly on soft soil that could be subject to collapsing.

In accordance with IS 2911 (Part I/Sec 3) -2010, the pile cap could be arranged through supposing that the load out of the column is spread at 45˚ out of the cap’s top up till the pile cap’s mid-depth out of the base of the pedestal or column.

Furthermore, the reaction out of piles could even be taken to be spread at 45˚ out of the pile’s edge, up till the pile cap’s mid-depth. For this reason, the utmost bending moment as well as shear forces must be figured out at significant segments.

Suppositions relevant in the Pile Caps’ design:

• Pile cap is completely set/rigid.
• Pile heads are pivoted toward the pile cap as well as for this reason no bending moment is sent to piles out of pile caps.
• As the piles are slight as well as elastic columns, the distortions as well as stress sharing are planers.

Pile Caps’ Design Constraints:

• Form of the pile cap.
• Pile cap’s depth.
• Quantity of steel to be offered.
• Setup of reinforcement.

Functional Characteristics on Pile cap Design:

• The dimension of the pile cap is set in such a manner that it has apparent overhang over the outmost pile no less than 100 mm, however if possible 150 mm.
• It must be quite deep to let the essential overlay of reinforcements out of column as well as piles.
• Furthermore, the clear cover toward the major reinforcement must not be below 40 mm.
• Moreover, the cap’s span to thickness ratio must not be in excess of 5 in order that pile cap is quite rigid to spread the load consistently toward the piles.

• Usually, its thickness must not be below 500 mm that might be decreased to 300 mm on the free peripheries.
• The piles must no less than 50 mm within/into the pile cap.
• A leveling course of not less 75 mm wide/thick concrete must be offered in the pile cap.

Lecturer: Mounika Meduri