foundation system of burj al arab

REINFORCEMENT REQUIREMENT OF PILE

The amount of reinforcement and its arrangement vary with the loading condition and installation and driving condition. The amount and arrangement of reinforcement for different types of pile are discussed below briefly.
Precast Pile

Longitudinal Reinforcement

The minimum amount of longitudinal reinforcement should be 1.5% of concrete section. At least 4 bars have to provide in a symmetrical pattern.

Lateral Tie Spacing

At each end of pile lateral tie reinforcement consisting of 6mm dia or larger have to place at a spacing not more than 75 mm center to center, or an equivalent spiral shall have to provide through a length equal to at least three times or the pitch of spiral may be increased to 300 mm.

Clear Cover

The cover of concrete over all the reinforcements including ties, should not be less than 70 mm anywhere through out the length of piles.

Cover should be measured clear from the main or longitudinal reinforcement.

Cast-in-situ Piles

- Minimum vertical reinforcement in bored cast-in-situ piles shall be four 13 mm dia bars and embedded at least half of the pile.

- Reinforcement should be assembled and and tied together and should be placed in the piles as a unit before the reinforced portion of the pile is filled with concrete.

- When hollow stem auger is used to install piles, the longitudinal steel reinforcement should be placed through ducts in the auger prior to filling the piles with concrete.

- All pile reinforcements should have a concrete cover of not less than 65 mm.

Under-reamed Bored Cast-in-Situ Piles

Longitudinal Reinforcement

- Minimum longitudinal reinforcement in stem shall be 0.4 %.

- Reinforcement is to be provided in the full length.

- Minimum 3 bars o 10 mm of diameter mild steel or 3 bars of 8 mm diameter high strength steel be used.

Transverse Reinforcement

Transverse reinforcement should be provided with bars not less than 6 mm in diameter and at a spacing not less than the stem diameter or 300 mm, whichever is less.

In case of cohesion less soil, under-reaming should not be done in both above and below ground water table.

The minimum depth of under-reaming bulb shall be either 2.75 m or below the level of stabilized moisture content, whichever is deeper.

Under-reaming Compaction Piles

Vertical reinforcement

Minimum four 12 mm dia bars should be provided, but for piles of length exceeding 5 m and diameter exceeding 375 mm, a minimum of six 12 mm dia bars shall be provided. For piles exceeding 400mm in dia, a minimum of six 12 mm dia bars shall be provided.

Transverse Reinforcement

The circular stirrups of such piles shall be provided with a minimum of 8 mm dia bars.

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