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Pile Group Load Distribution |
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Pile Group Load Distribution |
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This program distributes a concentrated load applied on a rigid pile cap to a group of piles. Force distribution is performed assuming a rigid pile cap and that all piles having equal vertical load resistance.
Distribution of loads to each pile due to the effect of load eccentricity is determined using a skew bending analysis. This considers simultaneous action about both X and Y axes.
The program is also an efficient method for determining loads on a pile group in the as driven arrangement.
Basic Usage
| • | Define the coordinate system, locating the applied vertical load and piles locations. For ease of use, it's wise to set up the system so all offset distances from the datum are positive. |
| • | Enter Load and Location for vertical loads only. Enter X and Y distances from the datum to center of applied load. |
| • | Enter Pile X and Y locations from the datum to the center of each pile. |
| • | Note: Only the first pile may be specified at location (0,0). For pile # 2 -> #10, at least one distance must be non-zero. The first (0,0) location encountered in rows #2 -> #10 will signal that the previous line was the last pile in the group. |
| • | Assumptions & Limitations |
| • | The pile cap is assumed rigid and the distribution is performed by calculating the properties of the pile group. |
| • | The program doesn't calculate punching shear or other such detailed items for a pile cap. |
Example
The data entry for this example is shown in the screen captures that accompany the Data Entry Tabs and Results & Graphics Tabs sections to follow.
Data Entry Tabs
This set of tabs provides entries for all input in this calculation. While you are entering data and switching between these tabs you can view the desired resulting information on the tabs on the right-hand side of the screen (calculated values, sketches, diagrams, etc.). A recalculation is performed after any entry data is changed. After each data entry you can view the results on the right-hand set of tabs.
General Tab
Total Axial Load
Enter the total Vertical load to be distributed to the piles in the pile group using the coordinate system you have defined. This indicates the distance from the datum (0,0) point to the point of load application. Note! Only vertical loads are allowed; no lateral shears.
X & Y Distance to Load
Distance from "Datum" point to where the load is applied.
Pile Locations
Distance from "Datum" to the pile.
Results & Graphics Tabs
This set of tabs provides the calculated values resulting from your input on the "Data Entry Tabs". Because a recalculation is performed with each data entry, the information on these tabs always reflects the accurate and current results, problem sketch, or stress/deflection diagram.
Results Tab
Center of Gravity
Using a simple center of gravity calculation assuming each pile is of equal resistance, the neutral axis of the pile group about both axes is determined.
Load Ecc. from CG
After the center of gravity of the pile group is located, the eccentricity of the applied load to the C.G. is calculated and will be used to determine the X-X and Y-Y axis moments on the pile group.
Group Inertia About Axis Ixx and Iyy are calculated by using:
l = SUM (A * d2 )
where...
d = Distance of each pile from the center of gravity
X-X & Y-Y moments
Using the applied load and eccentricity from the pile group center of gravity, the X-X and Y-Y axis moments on the pile group are calculated. This will be used in the equations detailed below to determine the loads to each pile.
Summary Of Pile Loads
Pile Number : Reference number for your convenience.
Coordinates : According to the user-defined coordinate system, enter the X and Y distances of each individual pile from datum (0,0).
Load/# Piles : This equals the total applied load divided by the number of piles.
Force from Rotation : Represents the force applied to each pile as a result of the induced moment about the X and Y axes.
The X-X axis bending load is calculated as:
[Mx * Iy - My * Ixy]Y + [ My * Ix - Mx * Ixy ]X
Iy*Ix - Ixy2 Iy*Ix - Ixy2
The Y-Y axis bending load is calculated as:
[My * Ix - Mx * Ixy]Y + [ Mx * Iy - My * Ixy]X
Ix*Iy - Ixy2 Ix*Iy - Ixy2
Pile Reaction
The total pile reaction is equal to the sum of the previous calculated forces.
Sketch Tab
This tab provides a sketch of the beam with loads and resulting values shown. Using the [Print Sketch] button will print the sketch in large scale on a single sheet of paper.
Sample Printout
