Pile Cap design
Pile cap definition – Pile Cap design example
A pile cap is outlined as a concrete block cast on the pinnacle of a cluster of piles, to transmit the load from the structure to the group of piles. Generally, pile cap transfers the load kind the structures to a pile group, then the load any transfers to firm soil.
External pressures on a pile are probably to be greatest near the ground surface. Ground stability increases with depth and pressure. The top of the pile thus, is additional at risk of movement and stress than the base of the pile. Pile caps are so incorporated so as to tie the pile heads along thus that individual pile movement and settlement is greatly reduced. Therefore stability of the pile group is greatly increased.
Pile Cap functions – Pile Cap design
To distribute a single load equally over the pile group and thus over a larger space of bearing potential,
To laterally stabilise individual piles therefore increasing overall stability of the group. And
To provide the necessary combined resistance to stresses founded by the superstructure and/or ground movement.
Pile caps are thick slabs used to tie a cluster of piles along to support and transmit column loads to the piles.
Pile Cap Arrangement – Pile Cap design
Spacing of the piles in the pile group The subsequent ought to be thought of when determining the spacing of the piles:
1. Overall value of the inspiration
2. Nature of the ground
3. Pile behaviour in the cluster
4. Resulting possible heave or compaction of ground causing harm to adjacent structures
5. Cost of Pile Cap design
6. Size and effective length of ground beam
7. Type and size of pile
Piles should be placed during 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 doable in the C.G. of hundreds transmitted from the structure to the cluster of piles.
- Within 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 methodology needs.
- The projection of the pile cap ought to be 10-15 cm.
The simplest pile layout is one without batter piles. Such a layout should be used if the magnitude of lateral forces is small. Since all piles don’t carry an equal portion of the load, axial pile capability can be reduced to 70 percent of the computed value to provide a good starting purpose to see an initial layout. In this case, the designer begins by dividing the biggest vertical load on the structure by the reduced pile capacity to get the approximate range of pile. If there are giant applied lateral forces, then batter piles are sometimes needed. Piles with flat batter 2.5 (V) to 1 (H), give bigger resistance to lateral masses and the less resistance to vertical loads. Piles with steep batters 5 (V) to 1 (H) provide greater vertical resistance and fewer lateral resistance. pile cap design
After the preliminary layout was developed remaining load cases ought to be investigated and also the layout revised to produce an economical layout. The goal ought to be to supply a pile layout in which most piles are loaded as near to capacity as practical for the critical loading cases with tips located at the same elevation for the varied pile teams at intervals a given monolith. Adjustments to the initial layout by the addition deletion, or relocation of piles at intervals the layout grid system could be needed. Generally, revisions to the pile batters can not be needed as a result of they were optimized throughout the initial pile layout. The designer is cautioned that the founding of piles at numerous elevations or in several strata might end in monolith instability and differential settlement.
Pile Cap design
- If the pile group is analyzed with a flexible base, then the forces needed to design the base are obtained directly from the structure model.
- If the pile cluster is analyzed with a rigid base, then a separate analysis is needed to see the stresses in the pile cap.
- An acceptable finite part model (frame, plate and plane stress or plane strain) should be used and ought to include all external hundreds (water, concrete, soil, etc. ) and pile reactions.
- There are many strategies for planning Pile Cap design from which we tend to could mention the subsequent:
1. Circulage Method
2. Beam Method
3. FEM methods