# Creating a Local Substructure Model for Soil-Structure Interaction from a Global Model

Once your global model is ready, you can use the workflow below to:

1. **Run a nonlinear analysis on the substructure** — useful for analyzing or checking slender columns independently.
2. **Run a soil-structure interaction (SSI) analysis** — incorporate nonlinear springs to evaluate the interaction between the soil and the structure.

The main benefit is that any change to the global model — or any modification that affects analysis results — can be pushed to the local model with a single sync. Change management stays simple.

## Prepare the Global Model for Substructure and Result Transfer

1. Prepare the global model for transfer. Navigate to **Organization > Cross-Project Data > Shared Substructure**. Select the **Support Line** and set **Transfer Result Extractions** to **Yes**.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-213736.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-213906.png?api=v2)
2. Navigate to **Organization > Cross-Project Data > Analysis Results > Bearing Forces** and select all bearings of the substructure together with the result cases used for force extraction. (See [Bearing Forces](/templates/steel-tub-girder-bridge-workflow/organization-stg/cross-project-data-stg/analysis-results-stg/bearing-forces-stg.md) for details.) Configure the extraction settings to match your use case.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215245.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215307.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215459.png?api=v2)
3. Open the **Extracted Forces** tab and click **Extract Forces**. The results appear in the spreadsheet. The global model is now ready to transfer the substructure model and its results.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215635.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215743.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-215834.png?api=v2)

## Set Up the Local Substructure Model from the Global Model

1. Open the **All-in-One Bridge Workflows** section and click **New Project** within it. Enter a name for the new project.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-124322.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-124508.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-124547.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-124835.png?api=v2)
2. Click **Data** to open the spreadsheet. On the left panel, click the gear icon ![](https://openbrim.atlassian.net/wiki/s/-505230918/6452/267b0663176c4f8787189805bf0a33b7c6d3998e/_/images/icons/emoticons/72/2699.png) to open the workflow picker, then choose **External References**.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-175247.png?api=v2)
3. In the tree view, click **Project Objects**. Open the three-dot menu and choose **Add Projects…**. Select your global / parent project from the list.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-125206.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-125244.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-125507.png?api=v2)
4. Open the three-dot menu again and choose **Shared Object** from the global model.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-125543.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241128-125617.png?api=v2)
5. Click **Sync Project** to complete the import.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-175639.png?api=v2)
6. Click **Zoom Extent** ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-205754.png?api=v2) to view the substructure. In the tree view, synced objects are shown in **green** instead of the default **blue**. In the spreadsheet, each synced object's name cell shows an attachment icon at the bottom-right. Each subsequent sync overwrites the local data for these objects with whatever the global model contains.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-205852.png?api=v2)
7. To protect specific objects from being overwritten — for example, when you are designing the pier cap or pier column and don't want their data changed by the next sync — open the three-dot menu next to the object and choose **Disable Sync**.

   Sync-disabled objects show:

   * A **purple** color in the tree view.
   * An **unlock icon** instead of the attachment icon in the spreadsheet cell.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-210430.png?api=v2)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-210506.png?api=v2)
8. With the substructure imported, add the additional objects needed for analysis. Create at least two construction stages:

   * **Stage 1** — construction of the substructure.
   * **Stage 2** — application of bearing loads.

   Then build the substructure inside Stage 1. (This guide assumes familiarity with creating stages and constructing substructure elements in OpenBrIM. If you need an introduction, see the **Steel I Girder Training Example**.)

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-210817.png?api=v2)
9. Set the **Nonlinear** property of the stages to **Yes** to enable nonlinear analysis.

   ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-224209.png?api=v2)
10. Define the bearing loads. To wire them to the analysis results extracted from the global model:

    1. Navigate to **External References > Project Analysis Results** in the tree view.
    2. Select all the cells in the results table.
    3. Click **Copy Parameter**.
    4. Paste the parameters into the bearing-load spreadsheet — an **f(x)** icon appears in the bottom-left of each cell.

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-211558.png?api=v2)

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-212731.png?api=v2)

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-212916.png?api=v2)
11. Define the **Soil Set** and **Soil Layers** (this guide assumes familiarity with creating soil sets and layers). Then return to the **Pile Layout FEA** tab and set **Soil Spring Type** to **Nonlinear Spring from the Soil Set**.

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-213233.png?api=v2)

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-212339.png?api=v2)

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-213302.png?api=v2)

    ![](https://openbrim.atlassian.net/wiki/download/attachments/2803269633/image-20241127-213314.png?api=v2)

{% hint style="warning" %}
Loads transferred from the superstructure may already include factors — for example, the Strength I combination typically applies a 1.25 factor to Dead Load. Those factors are **not** automatically applied to substructure self-weight in this local model, so you must apply the same factor to the substructure dead load yourself.

Wind loads applied directly to the substructure are also not transferred, because only forces at the bearing level are transferred. Define a separate wind-load case for the substructure if you need to account for it.
{% endhint %}


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