# Concrete U Girder

This section defines the Concrete U Girder properties including section variations, haunch thickness, and FEA settings.

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**Navigation:** Superstructure > Girders > Concrete U Girder

For detailed parameter explanations, see the [Concrete U Girder Reference](https://docs.openbrim.org/templates/concrete-u-girder-bridge-workflow/superstructure-cug/u-girder-cug/concrete-u-girder-cug).
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## Steps

### Step 1: Navigate to Concrete U Girder

Navigate to **Girders > Concrete U Girder** in the tree view.

![Navigation](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-120916.png?api=v2)

### Step 2: Assign Girder Layout

Click the **three-dots icon** on the Girder Layout cell and select **GL1** from the dropdown.

### Step 3: Edit Girder Sections

Click the **three-dots icon** on **Girder Sections** and select **Edit**.

![Edit Sections](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-121337.png?api=v2)

The CUG1 beam will have section variations according to station. The sections **U78G5** and **U54G5** (defined in the Sections page) are applied at different stations.

![Section Variations](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-122805.png?api=v2)

### Step 4: Define Section Stations

Select the **Reference Support Line** option.

Use the **Station Difference Along PGL** parameter to designate the specific station where each section is positioned.

![Station Definition](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-124238.png?api=v2)

### Step 5: Set Variation Transitions

Define the desired appearance of variation transitions between sections.

![Variation Transitions](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-132544.png?api=v2)

### Step 6: Apply Configuration to All Spans

Apply the station-dependent configuration for **SL1** (Reference Support Line) throughout the entire bridge span.

![All Spans](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-133101.png?api=v2)

### Step 7: Set Haunch Thickness

Enter **Haunch Thickness** as **4** inches.

![Haunch Thickness](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-134110.png?api=v2)

<details>

<summary><strong>Quick Tip:</strong> Haunch Thickness</summary>

The haunch is the concrete buildup between the top of the girder and the bottom of the deck slab.

![Haunch Diagram](https://openbrim.atlassian.net/wiki/download/attachments/2104689432/image-20230828-140549.png?api=v2)

</details>

### Step 8: Configure FEA Settings

Navigate to the **FEA Settings** tab.

![FEA Settings](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-134249.png?api=v2)

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When you define a **RigidSection** in the Section spreadsheet, OpenBrIM automatically assigns the **Rigid Section** parameter. The girder FE model uses FeLine elements for flanges and FeSurface elements for the web.
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### Step 9: Define Second Girder

For the second girder, use **GL2** in the Girder Layout.

![Second Girder](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-141332.png?api=v2)

Replicate all actions performed for **CUG1** for **CUG2**.

## Verification

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After completing these steps, the girders should appear as shown below.
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![Completed Girders 1](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-142708.png?api=v2)

![Completed Girders 2](https://openbrim.atlassian.net/wiki/download/attachments/2258731022/image-20230828-142744.png?api=v2)