# How to design a rectangular pile cap with spreadsheet

Given below, the demonstration of the spreadsheet that is used to create the design of rectangular pile cap.

The common features of the spreadsheet are explicitly discussed here. This spreadsheet is utilized for making the design (according to BS 8110-1:1997) of rectangular pile caps with 4 or more piles.

1.0 ASSUMPTIONS AND CONSTRAINTS OF THE SPREADSHEET:

1) The pile cap is supposed to be inflexible.

2) This spreadsheet is intended for rectangular pile caps. This spreadsheet is not applicable for octagonal or irregular shaped pile caps.

3) This spreadsheet can be only applied for pile caps containing single pedestal/column. Pile caps for multi-pedestals/columns are out of the extent of this spreadsheet.

4) Lowest number of piles should be 4. (Individual spreadsheets are formed with pile caps having 2 piles & 3 piles). Highest number of piles should be 28.

5) Centroid of pedestal is taken as the source for co-ordinate axes.

6) Eccentricity of horizontal loads relating to C.G. of pile cap is not taken into consideration.

7) Maximum load cases are constrained to 100.

8) The diagrams demonstrating the plan of pile cap is characteristic only; meant to provide the direction of co-ordinate axes. The number of piles/size of pile cap provided will not be modified on the basis of the input.

9) In order to verify the buoyancy condition, only two conditions are taken into consideration - design water table either at ground level or underneath the founding depth of pile cap.

Intermediate levels among these two are not considered.

2.0 FEATURES OF THE SPREADSHEET:

1) STAAD analysis output is directly entered as the input for design of pile cap.

2) There are choices to create the design of pile cap either for the actual pile loads or for the whole capacity of pile. To design with whole capacity of piles, all the pile loads are considered as compression capacity for working out the bottom reinforcement and all the pile loads are considered as tension capacity for working out the top reinforcement.

3) For quick reference, all inputs for the spreadsheet are illustrated in rose colour and the outputs are illustrated in yellow colour.

4) All cells excepting the input cells are locked to defend the spreadsheet against any unpremeditated change/modification.

5) Effect of water table is assessed in the spreadsheet. But, the loss in self weight of pile because of water table should be calculated in the tension capacity of pile.

To download the spreadsheet, click on the following link www.onlinecivilforum.com