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Axially Loaded Piles

This tutorial demonstrates the Axial Pile Analysis option in RSPile. Through this exercise you will learn how to analyze a single pile in multiple soil layers under axial loading using RSPile . This tutorial will also help to familiarize you with the product’s basic functions and features.

Topics Covered in this Tutorial:

  • Multi-layer model
  • Soil types for axially loaded piles
  • Pile properties
  • Axial loading conditions
  • Export data to Excel

Finished Product:

The finished product of this tutorial can be found in the Tutorial 1 - Axial Pile Analysis.rspile2 data file. All tutorial files installed with RSPile can be accessed by selecting File > Recent Folders > Tutorials Folder from the RSPile main menu.

Want to watch a video version of the tutorial? Check out our Youtube channel here.

1.0 Introduction - Using RSPile

The RSPile modeler provides two distinct views:

  • The Plan View is a top-down view of the ground surface.
  • The 3D View enables easy visualization of results in three dimensions.

RSPile Program interface

The Sidebar at the right of the screen provides a variety of viewing controls and the contour legend. By default, both views and the sidebar are visible, but their relative sizes can be scaled as desired.

2.0 Model

When the RSPile program is started, a new blank document is already opened, allowing you to begin creating a model immediately.

Note on sign convention: In RSPile, the default ground surface is at depth = 0, depth is positive downwards, and compressive stress is positive.

2.1 PROJECT SETTINGS

The Project Settings is where you can change the analysis type, tolerance, number of iterations allowed, and the number of pile segments to be used in the analysis. To open the Project Settings:

  1. Select Analysis > Project Settings (CTRL + J) or click on the Project Settings Icon Project Settings icon in the toolbar.
  2. Project Settings Dialog

  3. Set the Pile Analysis Type to Axially Loaded Pile.
  4. For this tutorial, keep the default values as they are.
  5. Tip: The default units for RSPile are metric. To change this setting, select Analysis > Units.

    Notice that in addition to the Axially Loaded and Laterally Loaded options, under the Individual Pile Analysis header we also have an Axially / Laterally Loaded option. We have provided the Axially / Laterally Loaded analysis type specifically for RSPile integration with Slide2.

    Note: With regards to the Analysis Settings, keep in mind that larger values of Pile Segments and Number of Iterations will increase the computation time, as calculations are performed at every node down the length of the pile.

  6. Click OK to close the dialog.

2.2 SOIL PROPERTIES

  1. Select Soils > Define Soil Properties (CTRL + 8) or click on the Define Soil Properties icon Define Soil Properties icon in the toolbar.
  2. In this dialog you can define the properties related to the Q-z, t-z, and p-y curves. There is a tab for each analysis type (Axial, Lateral, Driven) as well as for datum dependency. The Datum Dependency tab allows users to control linearly varying properties. While you can click through all tabs, you will only be able to edit material information that is relevant to the Pile Analysis Type selected in the Project Settings.

    Soil Properties dialog

  3. Enter the following soil properties:
  4. Soil Property 1:

    • Name = Clay
    • Unit Weight = 17 kN/m3
    • Soil Type = API Clay
    • Undrained Shear Strength = 22 kPa
    • Remolded Shear Strength = 15 kPa
    • Maximum Unit Skin Friction = 1,000,000 kPa
    • Maximum Unit End Bearing Resistance = 1,000,000 kPa

    Soil Property 2:

    • Name = Sand
    • Unit Weight = 20 kN/m3
    • Soil Type = API Sand
    • Friction Angle = 35 degrees
    • Coefficient of Lateral Earth Pressure = 1
    • Bearing Capacity Factor = 40
    • Maximum Unit Skin Friction = 1,000,000 kPa
    • Maximum Unit End Bearing Resistance = 1,000,000 kPa
  5. Click OK to save your input and exit the dialog.

2.3 SOIL LAYERS

RSPile supports multiple boreholes and non-horizontal soil strata. When multiple boreholes are defined, the program will automatically interpolate between the boreholes. In this tutorial, we will model horizontal soil strata with a single borehole. To begin:

  1. Select Soils > Borehole Editor or click on the Borehole Editor icon Edit All Boreholes icon in the toolbar.
  2. The default soil column has a single layer and is located at (0, 0). To change the location, enter coordinates for X and Y. We will keep it (0,0) here.

    Edit borehole dialog

  3. Click on Insert Layer Below to add another layer below the first. The Name column will fill in by soil property sequence.
  4. Layers are defined by thickness by default, but may be defined by top and bottom elevation. This may be changed by toggling Define Layers by Thickness.

  5. Specify the following layer thicknesses:
  6. #

    Name

    Thickness

    Top Elevation

    Bottom Elevation

    1

    Clay

    10

    0

    -10

    2

    Sand

    10

    -10

    -20

    The Soil Layer Column on the right side of the dialog will update automatically as layer thicknesses are defined.

  7. Click OK to save your input and exit the dialog.

2.4 PILE SECTION PROPERTIES

Pile Sections are used to create your Pile Type. Pile types can be made of multiple pile sections depending on the complexity and composition of your pile. For this tutorial we will just define one pile section.

  1. Select Piles > Pile Section Properties or click on the Pile Section with Pencil Icon Define Pile Section Properties icon in the toolbar.
  2. Select Pile Section 1 and enter the properties displayed in the table below:
  3. Name

    Cross Section

    Type

    Pile Outside Diameter (m)

    Pipe Wall Thickness (m)

    Young's Modulus (kPa)

    Steel Pipe

    Pipe

    Elastic

    0.5

    0.02

    2e8

    Define Pile Section Properties Dialog

  4. Click OK to save your input and exit the dialog.

2.5 ADDING A PILE

Select Piles > Add Pile or click on the Add single pile icon Add Single Pile icon in the toolbar.

We have centralized all aspects of the pile definition in the “Add Pile” dialog. For the Axially Loaded, Laterally Loaded and Axially / Laterally Loaded analysis types the Add Single Pile and Add Pile Pattern options are available. For the Grouped Pile Analysis type, the Cap Designer must be used. In the Add Pile dialog, users specify:

  • Geometry – basic pile properties such as length and orientation are specified
  • Loading – pile head loading definition
  • Displacement – displacement profile or axial /lateral resistance analysis
  • Multipliers – p-y, t-z, Q-z multipliers can be defined
  • Advanced – advanced analysis options such as Pile Length Analysis (the availability of the Advanced options varies based on pile analysis type)

See the RSPile Help for more information on specifying p-y multipliers, displacements, and advanced features.

2.5.1 Geometry

The Geometry tab allows users to specify the pile type and location of a single pile.

The pile type selected determines the pile sections the pile is composed of, the pile length and the alignment of the single pile. Alignment options include: elevation, ground slope angle, rotation angle, and orientation. Orientation may be specified in one of two ways: Alpha/Beta angle, or Vector position.

Add Pile - Geometry tab

For this tutorial, click on the edit icon for the Pile Type and enter the following properties for Pile Type 1:

Name

Section Property

Pile Head Elevation (m)

Length (m)

Orientation

Ground Slope Angle

Alpha Angle

Beta Angle

Rotation Angle

Pile Type 1

Steel Pipe

0

17

0

0

90

0

Edit Pile Type dialog

Click OK to close the Edit Pile Type dialog.

Note: By default, the Location fields are grayed out and the mouse selection option is selected. The location of the pile can be entered in one of several ways. With the mouse selection option the pile location is entered graphically on the next screen by clicking on a location on the Plan View. If you deselect this option you can instead place your pile by entering coordinates into the X and Y fields. For this tutorial we will leave the default option selected.

2.5.2 Loading

  1. Select the Loading tab.
  2. Add a new loading property by selecting the Green Plus icon green plus icon.

RSPile provides users with the flexibility to analyze multiple piles in a single file, and the Loading Property manager tracks all the pile head loads for the entire model. A different Load Property can be defined for each pile, or the same Load Property can be used for all of the piles in the file.

With regards to load type, two options are available: cyclic or static loading. If cyclic loading is chosen, the number of load cycles may be specified, depending on the soil types used.

Axial Analysis only supports axial loading. Since we are looking at a single pile in this file we will add one load property only.

  1. Specify the following value:
  • Loading Property = Load Property 1
  • Loading = Static
  • Loading Factor Profile = None
  • Type = Force Z (kN)
  • Value = 100
  • Depth (m) = 0

Add single pile dialog - loading tab

The Displacement, Multipliers, and Advanced tabs will be explored in later tutorials.

  1. Click OK to save settings and close the dialog.

2.5.3 Placement

After clicking OK, RSPile will prompt the user to enter the (x, y) coordinates of the new single pile. You may enter the location manually in the prompt line in the bottom right of the screen or click a point on the Plan View to place it.

  1. Enter Location = (0, 0) in the prompt line in the bottom right of the screen.
  2. Press Enter.

Your model should now look like this. Notice that the soil column has now updated to reflect the strata.

3D model

3.0 Results

Save and compute the file by clicking on the Calcuator icon Compute icon in the toolbar.

3.1 RESULTS VISUALIZATION

RSPile allows for the 3D visualization of results along the length of the pile. Use the Data Type drop down to control what results are shown.

Data Type drop down menu

Pile Results may be toggled on or off using the View Controls in the sidebar.

View Controls - Pile results checkbox

3.2 CHARTS

In the Plan View, right-click on the pile and select Graph Pile icon Graph Pile. The RSPile results section presents several default graphs and a table of results. You should see the following:

Graph pile

Axial pile analysis generates two default graphs, including:

  • Axial Displacement vs. Depth
  • Axial Force vs. Depth

The sidebar contains the Chart Controls, which allow you to select what information is displayed, and customize the appearance.

Tip: Results may be displayed in scientific notation or decimal form. To format the results, select Number Format from the toolbar and select the desired form. The number of decimals to be displayed may also be adjusted.

3.3 EXPORT TO EXCEL

From the Results tab you can export your data to Excel. To do so, click on the Excel icon Export Data to Excel icon in the toolbar.

Each data type is exported to its own sheet in the Excel file.

4.0 Report Generator

The Report Generator presents a formatted summary of input data and analysis results. Go back to the model view and click on the Info viewer icon Report Generator icon in the toolbar. A new window will open and you should see a summary of the model input data including:

  • Project Summary
  • Soil Layers
  • Soil Properties
  • Pile Section Properties
  • Pile Types
  • Pile Settings

The tool bar contains the Report Generator Controls, which allow you to select what information is displayed, and customize the appearance of the report.

The data can be exported in a variety of ways: it may be manually copied, viewed in a browser, printed, or the information may be saved as a .pdf file. Prior to printing the file, results may be formatted to your specifications.

Click on the Close Window icon Close Window icon in the Report Generator toolbar to close the viewer and return to the model view.

5.0 Property Tables

To end this introductory tutorial, we will highlight the Drawing Tools included in RSPile. These tools include addition of Soil and Pile Properties tables.

To add these tables to the model view, select Tools > Add Tool > Soil Properties Table, or Pile Properties Table. Click anywhere on the Plan View to add a table.

Once added, the tables may be edited, moved, or formatted as desired by using the right click menu and selecting Format Tool.

This concludes the Axial Pile Analysis Tutorial. You may now exit the RSPile program.


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