Structville is a media channel dedicated to civil engineering designs, tutorials, research, and general development. At Structville, we stop at nothing in giving you new dimensions to the profession of civil engineering. Sign in Join. Sign in. Forgot your password? Create an account. Privacy Policy. Sign up. Password recovery. Recover your password. Get help. Thursday, January 13, About Us. Fig 1: Layout of triangular pile cap.
Fig 2: 3D rendering of the pile cap model. Fig 3: Axial load on Single Pile. Fig 4: Axial load on twin pile. Fig 5: Bending moment in the x-direction. Fig 6: Bending moment in the y-direction. Comparison Table Table 1: Comparison of results between manual bending theory and finite element analysis. Underpinning of Foundations. How to Determine the Depth of Foundation. Please enter your comment! Please enter your name here. You have entered an incorrect email address!
Download Free PDF. Ayodele Akin-Adamu. A short summary of this paper. Download Download PDF. Translate PDF. The group piles transfer load to the soil either by end bearing at the base of the piles, friction along the length of piles or both. Pile caps are thick slabs used to tie a group of piles together to support and transmit the column loads to the piles.
Pile cap transmit vertical, horizontal and moment load to the pile group. Piles can be of different shapes; rectangular, square, hexagonal and other polygonal shapes. Tie beams may be used to connect the pile caps, to reduce or totally resist the horizontal force transmitted from the column shafts. The minimum number of small diameter piles which is permitted in an isolated pile cap is three.
Caps for single piles must be interconnected by tie beams in two directions, and for twin piles by tie beams in a line transverse to the common axis of the pair. A single large-diameter pile carrying a column does not necessarily require a cap. Any weak concrete or laitance at the pile head can be cut away and the projecting reinforcing bars bonded to the starter bars of the column reinforcement. To facilitate construction, tie beams should be arranged, where possible, to pass across the tops of the pile caps and not to frame into the sides of the caps, the connection between the cap and the ground beam being provided by column starter bars and by the friction and bond between cap and beam.
The image shows the piles, pile cap and tie beam layout. BS clause 3. Bending theory method states that the pile cap can be considered to behave as a short deep beam, transferring the load from column to piles by bending action, just like the pad footing.
This method seems most appropriate for a two-pile cap. Truss analogy method states that the pile-cap may be imagined to act as a space frame, the inclined lines of force linking the underside of the column to the tops of the piles being assumed to form compression members and the pile heads being linked together by reinforcement acting as horizontal tension members. This assumption appears particularly appropriate for analysing the more 'three-dimensional' pile caps, such as those required for three or more piles.
NOTE: Unlike other foundation base like pad, strip, and raft, the pile cap does not require safe bearing capacity of the soil as input variable in the design of pile cap. This is because the pile cap is supported on the piles, rather than the soil. Also the length of the piles is not required as input variable in the design of pile cap. This is to Orion 18 software users, Orion 18 software only sizes the pile cap, i.
It does not calculate bending moment, shear force, and punching shear in the pile cap. The image shows the Main reinforcement arrangement for Pile caps for two, three and four piles. Note that the pile cap with two piles has only one main reinforcement, and minimum reinforcement is provided in the other direction as specified in code of practice. For the pile cap with three piles, one main reinforcement connects two piles together, while the other main reinforcement runs along only one pile. Pile cap main reinforcements are inform of U bars, running along both direction.
While side bars inform of links are used to control cracking in the pile caps. The side bars are evenly spaced along the depth of the pile cap.
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