📐 Piles Stiffness Calibration Tool

The Piles Stiffness Calibration Tool is a CSI ETABS Plugin developed by Buro Happold to assist structural and geotechnical engineers in automating the calibration of pile stiffnesses under existing and proposed loads.

It runs parallel analyses in:

• ETABS → computes structural loads applied onto piles
• Oasys PDisp → determines pile stiffness

The process continues until convergence criteria are met, and outputs are automatically documented for engineers.

1. Open ETABS and create a new model.
2. Navigate to Tools → Add/Show Plugins.
3. In External Plugin Data, click Browse and select Piles_Stiffness_Calibration.dll.
4. Confirm details and click Add.
5. Click OK. The plugin will now appear under the Tools menu.

Figure 2: Accessing the tool via ETABS UI

Prerequisites:

• Visual Studio with .NET Framework desktop development (restore NuGet packages).
• ETABS 22 installed at C:\Program Files\Computers and Structures\ETABS 22\ (provides ETABSv1.dll and CSiDetailAPI.dll).
• Microsoft Excel (Office interop assemblies).
• Oasys PDisp 20.1 at runtime. Its COM interop assembly (Interop.pdispauto_20_1.dll) is committed in PilesStiffnessCalibration/lib/, so it is not needed to compile.

Access the plugin directly from the Tools Menu in ETABS.

Displays logo, name, version, and copyright.

Figure 3: Tool’s Splashscreen Window

Contains description, algorithm, UI features, and limitations.

Figure 4: Tool’s AboutBox Window

Main interface for selecting inputs, running iterations, and monitoring progress.

Figure 5: Tool’s Inputs Form Window

• Groups – pile nodes grouped in ETABS
• Load Combinations – single selection required
• Piles Stiffness Boundary Condition:
  • All Rigid Supports
  • All Same Stiffness [kN/mm]
  • Import from Serialized File

• PDisp File – must match pile node names with ETABS
• Maximum Displacement Variation – % threshold for convergence
• Maximum Number of Iterations – 2–100

Figure 6: PDisp Model (3D View + Pile Points List)

Iteration results serialized in JSON for lightweight storage and cross-platform use.

Figure 7: Sample JSON File Content

Import JSON into Grasshopper for advanced 3D visualization.

Figure 8: C# Component for JSON deserialization

Figure 9: 3D Visualization in Rhino via Grasshopper

Automatically generated tables and charts for iteration outputs.

Figure 10: Excel Outputs – Table & Charts

Saved per iteration for full traceability.

1. Run calibration in ETABS + PDisp.
2. Export JSON results.
3. Import JSON into Grasshopper for visualization.
4. Review Excel outputs for iteration trends.
5. Access saved ETABS/PDisp models for detailed analysis.