RAFT-FEM™ A SIMPLE TOOL For Pile-Raft Foundation Analysis & Design
- Adisorn O.
- 9 hours ago
- 4 min read
Design Faster with Confidence
In foundation engineering, there is often a gap between simplified hand calculations and large-scale finite element software. Engineers need a tool that is fast, practical, and easy to use for everyday projects without spending hours building complex models.
RAFT-FEM™ Mat Foundation Analysis was developed to bridge that gap.
The software provides rapid finite element analysis of mat foundations, pile-supported mats, and pile raft foundations, allowing engineers to quickly evaluate load distribution, foundation behavior, and preliminary reinforcement requirements.
Why RAFT-FEM™?
Many foundation projects require quick answers during the conceptual and preliminary design stages:
- How much load is carried by each pile?
- Is the mat foundation flexible or rigid?
- What foundation thickness is required?
- Where are the critical bending moments?
- What reinforcement will likely be required?
- Is the pile arrangement balanced?
Traditional 3D analysis software can answer these questions, but model preparation often takes longer than the actual engineering evaluation.
RAFT-FEM™ focuses on efficiency.
Engineers can generate a finite element model within minutes and obtain meaningful design information immediately.
## Flexible Foundation and Pile Raft Analysis
The program is particularly useful for:
### Mat Foundations
- Pile-Raft, pile and shallow Foundations
- Combined foundations
- Large equipment foundations
- Industrial foundations
### Pile-Supported Mat Foundations
- Pile caps with multiple columns
-Shear walls with arbitrary shape
- Large pile groups
- Transfer foundations
- High-rise building mat foundations
### Pile-Raft Foundations
- Settlement-sensitive structures
- Hybrid pile-soil load sharing systems (k_soil_bearing + k_pile_spring)
- Preliminary optimization studies
The software helps engineers understand how loads are distributed between piles and the foundation slab before moving to detailed design.
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## Easy Input System
One of the major goals of RAFT-FEM™ is simplicity.
### Foundation Boundary
Users define the boundary of the foundation using polygon coordinates:
Node X Y
1 0.0 0.0
2 8.0 0.0
3 8.0 6.0
4 0.0 6.0
1 0.0 0.0 (To ensure the closure of the polygon)
The software automatically:
- Generates finite element meshes (Q4) based on the user-defined maximum size
- Creates nodal connectivity
- Prepares analysis data, i.e., stiffness, load vector
### Pile Locations
Pile locations are entered directly:
Pile X Y Kz
1 1.5 1.5 60000
2 6.5 1.5 60000
3 1.5 4.5 60000
4 6.5 4.5 60000
### Column Loads
Engineers simply specify column coordinates and loads:
Column X Y CX CY Fz MX MY
C1 4.0 3.0 0.6 0.6 -10000 200 0
.
.
No complicated modeling procedures are required.
Reissner-Mindlin Plate Formulation
At the heart of RAFT-FEM™ is a robust finite element formulation based on the:
4-Node Reissner-Mindlin Plate Element
The formulation includes:
- Transverse displacement
- Plate bending
- Shear deformation effects
- Thick and moderately thick slab behavior
This makes the program suitable for:
- Thick pile caps
- Transfer mats
- Deep foundation slabs
- Pile raft systems
The Reissner-Mindlin formulation provides a practical balance between accuracy and computational efficiency.
Rapid Pile Load Distribution Assessment
One of the most valuable capabilities is automatic pile load recovery.
The software calculates:
- Individual pile reactions
- Maximum pile load
- Minimum pile load
- Pile load ratios
- Pile load contour maps
Engineers can immediately identify:
- Overloaded piles
- Uneven load sharing
- Effects of column eccentricity
- Foundation flexibility behavior
This capability is extremely useful during preliminary design and optimization studies.
Structural Design Information
Beyond displacement analysis, RAFT-FEM™ provides engineering quantities required for design.
Bending Moments
- Mx
- My
- Mxy
Shear Forces
- Qx
- Qy
Foundation Deformation
- Settlement contours
- Deflected shapes
Reinforcement Assessment
The program can compute the flexural rebar and perform shear check following ACI318-23 requirements:
Required reinforcement areas (mm2/m)
High-demand regions
Punching shear check from column dimension and cap thickness
One-way shear stress check
Punching shear check around pile shall be manually checked by user
This allows engineers to move rapidly from analysis to design decisions.
Powerful Visualization Tools
Engineering decisions become easier when results are visualized clearly.
RAFT-FEM includes contour plotting capabilities for:
- Vertical displacement
- Pile reactions
- Mx moments
- My moments
- Twisting moments Mxy
- Shear forces Qx
- Shear forces Qy
-As, top & As, bottom in x and y direction based on Wood-Armer's concept
-One-way shear stress in x and y direction
Engineers can quickly identify critical regions and understand structural behavior visually.
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Typical Workflow
### Step 1
Define foundation boundary as polygonal
### Step 2
Specify pile locations and spring stiffness.
### Step 3
Enter column locations, dimensions, and transferred loads.
### Step 4
Generate finite element mesh automatically.
### Step 5
Run analysis.
### Step 6
Review:
- Pile reactions
- Settlement contours
- Moment diagrams
- Shear distributions
### Step 7
Perform preliminary concrete design.
The entire process typically requires only a fraction of the time needed for conventional finite element software.
-Flexural rebar
-Punching shear check
-One-way shear stress check DCR
Practical Applications
RAFT-FEM™ is ideal for:
- Preliminary foundation sizing
- Feasibility studies
- Alternative pile layout evaluation
- Pile raft behavior assessment
- Load distribution verification
- Foundation optimization studies
- Consultant design offices
- Construction engineering support
Engineering Efficiency Through Simplicity
RAFT-FEM™ Mat Foundation Analysis was created with one objective:
Provide engineers with rapid, practical finite element analysis for everyday foundation design problems.
By combining:
- Easy model generation
- Reissner-Mindlin plate elements
- Flexible foundation analysis
- Pile load distribution assessment
- Concrete design evaluation
- Professional visualization tools
The software allows engineers to obtain reliable answers quickly and focus on engineering judgment rather than model preparation.
RAFT-FEM™
### Fast Foundation Engineering for Practical Design ###
Design Faster with Confidence.
References
M Bischoff, Advanced Finite Element Method, Lecture notes at Technische Universität München, 2002
KJ Bathe, Finite Element Procedures, Prentice-Hall, 1996
Mukhopadhyay and Sheikh, Matrix and Finite Element Analyses of Structures, Springer 2022
