What is pile cap in pile foundation?

A pile cap is a thick concrete mat that rests on concrete or timber piles that have been driven into soft or unstable ground to provide a suitable stable foundation. The cast concrete pile cap distributes the load of the building into the piles.

What is the purpose of designing pile cap?

These pile cap shapes minimize the plan area for a symmetrical arrangement of piles about the load. The pile cap should overhang the outer piles by at least 150mm but should not be excessive, generally not more than the diameter of the pile diameter.

What is the practical minimum depth for pile cap?

The overall depth of pile cap shall also be selected such that the effective depth of bottom reinforcement is at least 12 inches.

How do I know how many piles I need?

Allowable load and spacing. Both the dynamic and static formulas indicate that an allowable load of 15 tons per pile is reason- able. The number of piles required to support the load is 180/15 = 12 piles.

What is pile spring constant?

The “pile spring constant” (N/mm) can be calculated from the pile material’s Modulus of Elasticity. Pile elastic shortening under load can be calculated. The soil-pile spring constant can be determined by a pile load test: In my sketch the red line (approximately) parallels the pile settlement graph.

Is pile cap necessary?

Deep foundations are necessary where the bearing capacity of the surface soils is not adequate and so loads need to be transferred to deeper layers with higher bearing capacity. …

How do pile foundations work?

Piles are pushed into the ground to act as a steady support for structures built on top of them. Piles transfer the loads from structures to hard strata, rocks, or soil with high bearing capacity. The piles support the structure by remaining solidly placed in the soil.

How do I know my pile cap size?

Consider the design of a pile cap supporting two pile and a single column on the pile cap. consider 150mm offset from the pile and space between piles as 2.5 times pile diameter. Effective depth, d = 1000-50-20/2 = 940 mm > 750mm; (2.5×600/2) Ok.

How is pile cap thickness calculated?

Here is how to assume the thickness of the pile cap:

1. If diameter of pile < 550mm: thickness = 2 x diameter of pile.
2. If diameter of pile > 550mm: thickness = 1/3[(8 x diameter of pile)-600]

How do you size a pile cap?

Wrap a length of string around the top of your pile (where a piling cap would go), and mark the length of the string (or cut it). Measure the string and then divide that number (the circumference) by 3.14159 (pi) to get the diameter of your pile.

How do you calculate pile spacing?

Cohesion Piles: Spacing S = 3.5d + 0.02L Here d is the diameter of the pile and L is its length. The standard also stipulates for pile capacity till 300 kN, the distance from the edge of the pile to the pile stem must be 100mm.

When do you need a pile cap Foundation?

The allowable bearing capacity usually dictates if a pile cap foundation is required. Though the structural engineer can initially decide if the pile cap is needed at the early stage of design through other considerations as discussed in the previous article, a soil investigation report should confirm otherwise.

How to design a raft foundation using CsI-safe?

SAFE is a powerful tool to design simple to complex slabs, pile caps and raft foundations using different specified codes. This article will help you through on how to design a raft foundation and their design considerations using SAFE.

When to use pile caps in structural design?

Though the structural engineer can initially decide if the pile cap is needed at the early stage of design through other considerations as discussed in the previous article, a soil investigation report should confirm otherwise. Once the soil investigation has been completed, the soil laboratory will confirm and recommend the use of pile caps.

Which is the best tool to design a raft foundation?

But thanks to available design software, these complexities narrows down. Perhaps the most popular tool to design a Raft Foundation is through the aid of SAFE program developed by CSI. SAFE is a powerful tool to design simple to complex slabs, pile caps and raft foundations using different specified codes.