MasterRC Pile Cap Design 19-1

19 MasterRC Pile Cap Design Analysis, Design, Detailing, Scheduling and Drafting of Standard Pile Caps For 2 to 9 Pile Groups 19.1 Introduction

• Pile caps are analysed and designed to BS 8110 or SABS 0100 for concentrically, axially loaded standard shaped pile caps with up to 9 piles in the group.

• As input data is altered, the calculations and graphics update immediately. • The general form of the pile caps follows the conventions established by Whittle and

Beattie (Concrete, 1972). • The reinforcement in the pile cap is automatically detailed and can be printed to the

printer or exported to a DXF file or to the MasterRC detailing package. • Several pile caps can be contained within one file.

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Typical export to MasterRC

19.2 Pile Capacity and Loading

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The following data is input:- • pile diameter for a circular pile (or width for a square pile) • safe working load (in kilonewtons) • pile spacing (no. of pile diameters) • overall pile cap depth (mm) • minimum number of piles required for each design or opt to have the program

calculate the minimum number • dead and live loads (kN) • relevant factors of safety

19.3 Design Methods Several design methods are available – beam analogy, truss analogy or a comparison of both methods, with the user having the option to select the minimum or maximum from the design comparison. When using the beam analogy, based on bending theory according to BS8110:Part 1:1997, there is the option to design for the Net ULS Loads – the column loads ignoring the self weight of the pile cap. Enhanced shear stress capacity is taken into account when checking plane and punching shear with the shear stress limited by clause 3.11.4.4b. In truss analogy there is the option to check the concrete compression zone assuming it’s width to be the same diameter as that of the pile. When piles are greater than 3 diameters apart, any steel outside the 3 diameter bands is ignored.

19.4 Concrete and Main Reinforcement Details

Concrete details and reinforcement grades, diameters and spacings are entered. There is also an option to use square piles rather than circular. The overhang dimension from the edge of the pile to the edge of the pile cap is also entered. The minimum dimension is normally150mm for a circular or square pile. The program allows for the square pile to

MasterRC Pile Cap Design 19-4

have been driven rotated at 45 degrees on plan (worst orientation), hence giving a distance of (0.707x pile dia + overhang dimension) from the centre of the pile to the edge of the cap. The ‘Top margin’ box allows the overall drawing location to be modified on screen. Enter a positive value to move the drawings up or a negative value to move them down. Note that you can have several pile caps (briefs) in one file. Hence, all piles caps in one project can be easily managed. If all the pile caps are saved in the same file, then a single schedule will be created for all the caps, with the bars being rationalised. To add a new brief to a file, click on the button, give the new brief a relevant title and continue the design by entering the data for that new pile cap. Use the and

buttons to manage the briefs for each file. You can navigate through the briefs using the up and down arrows to the right of the brief title area or by dropping the list and selecting the brief you wish to work on. 19.5 Side and Upper Reinforcement Details

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The side reinforcement information is entered including side bar detailing style. A top nominal reinforcement cage can be added if desired. 19.6 Printing Results Graphics and calculations can be printed out using the Print option from the top menu, to print a single brief or all the briefs in a file. You can also use the icons below the top menu. If you have PowerPad the results can be exported to a Word document.

Switch graphics on or off when exporting or printing. Edit project title and job references. Print current or all briefs to printer. Export current or all briefs to Word (PowerPad users only).

19.7 Exporting RC Details Using the Export menu, the RC detailing of the pile caps can be exported directly to the printer, saved as a DXF file for opening in any drafting system, or exported to MasterRC within AutoCAD (requires MasterRC licence) for further manipulation, if required. The pile caps reinforcement can also be scheduled within these environments. You can choose to detail the reinforcement to BS 4466, BS 8666 or SABS 082. If all the pile caps in a project are saved in the same file, then a single schedule will be created for all the caps, with the bars being rationalised. The icon switches the graphic dimensions off and on. The icon switches the pile centre lines on.

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Exported DXF file

Typical Schedule