Pile Group
Published: 28/05/26, Updated:
Version: 1.0.0
Calculation performs the analysis of a pile group subjected to combined axial loads, shear forces, and bending moments from one or more columns. The applied column loads are translated to the centroid of the pile group and the resultant forces are resolved into individual pile reactions using the elastic method.
Assumptions
The following assumptions are considered in analysis:
The pile cap is assumed to be rigid and does not deflect under load.
All piles are assumed to have the same stiffness and cross-section.
Loads are applied at ULS and no load factors are applied by the calculator.
Column loads are transferred to the pile group centroid using rigid body mechanics.
Limitations
The calculation has the following limitations:
Pile group analysis is based on the elastic method only.
Pile skin friction and soil-structure interaction are not considered.
Maximum number of piles is limited to 50 in any geometrical arrangement.
Maximum number of columns is limited to 20.
Input Variables
The following input variables can be specified in the form.
| Symbol | Description | Units | Limits |
|---|---|---|---|
| hcap | Pile Cap Height | m / ft | hcap > 0 |
| h | Distance to Top of Pile (h<sub>cap</sub> − e) | m / ft | h > 0 |
| d | Pile Diameter | mm / in | d > 0 |
| Qp | Pile Compressive Capacity | kN / kips | Qp > 0 |
| Qt | Pile Tensile Capacity | kN / kips | Qt > 0 |
| Qs | Pile Shear Capacity | kN / kips | Qs > 0 |
| e | Pile Embedment Depth | m / ft | e ≥ 0 |
| smin | Minimum Horizontal Pile Distance | m / ft | smin ≥ 0 |
| Xp | Pile X coordinate | m / ft | |Xp| ≤ 100 m |
| Yp | Pile Y coordinate | m / ft | |Yp| ≤ 100 m |
| Xc | Column X coordinate | m / ft | |Xc| ≤ 100 m |
| Yc | Column Y coordinate | m / ft | |Yc| ≤ 100 m |
| b | Column width | mm / in | 0 < b < 3000 mm |
| hc | Column breadth | mm / in | 0 < hc < 3000 mm |
| Pz | Column axial load | kN / kips | |Pz| < 999 MN |
| Hx | Column shear force (X) | kN / kips | |Hx| < 999 MN |
| Hy | Column shear force (Y) | kN / kips | |Hy| < 999 MN |
| Mx | Column moment about X | kNm / kip-ft | |Mx| < 999 MNm |
| My | Column moment about Y | kNm / kip-ft | |My| < 999 MNm |
| Mz | Column torsional moment (Z) | kNm / kip-ft | |Mz| < 999 MNm |
Result Variables
The results are categorized and resultant tables are shown for easy navigation. Result variables are shown below.
| Symbol | Description | Units |
|---|---|---|
| Centroidx | Pile group centroid X coordinate | m / ft |
| Centroidy | Pile group centroid Y coordinate | m / ft |
| Ix | Pile group moment of inertia about X-axis | m² / ft² |
| Iy | Pile group moment of inertia about Y-axis | m² / ft² |
| Ixy | Pile group product of inertia | m² / ft² |
| J | Pile group polar moment of inertia | m² / ft² |
| θ | Pile group principal angle of rotation | ° |
| ∑Pz | Sum of column axial loads | kN / kips |
| ∑Hx | Sum of column shear forces in X direction | kN / kips |
| ∑Hy | Sum of column shear forces in Y direction | kN / kips |
| ∑Mx | Sum of column moments about X axis | kNm / kip-ft |
| ∑My | Sum of column moments about Y axis | kNm / kip-ft |
| ∑Mz | Sum of column moments about Z axis | kNm / kip-ft |
| Rz,max | Maximum pile compression vs allowable compression capacity | kN / kips |
| Rz,min | Maximum pile tension vs allowable tension capacity | kN / kips |
| Rhx,max | Maximum horizontal reaction along X vs allowable horizontal capacity | kN / kips |
| Rhy,max | Maximum horizontal reaction along Y vs allowable horizontal capacity | kN / kips |
| Rh,max | Maximum resultant horizontal pile reaction vs allowable horizontal capacity | kN / kips |
| smin,act | Minimum actual horizontal pile spacing vs minimum required pile distance | m / ft |
Standards
None
References
BS EN 1997-1:2004 — Eurocode 7: Geotechnical Design — Part 1: General Rules
Tomlinson, M. & Woodward, J. (2014) — Pile Design and Construction Practice, 6th Edition, CRC Press
Poulos, H.G. & Davis, E.H. (1980) — Pile Foundation Analysis and Design, Wiley
| Release Date | Version | Description |
|---|---|---|
| January 2024 | 1.0.0 | Initial release. |