> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/superstructure-ex1-stg/steel-girders-ex1-stg/tub-girder-ex1-stg.md).
# Tub Girder
This section defines the steel tub girder geometry with station-dependent plate dimensions.
{% hint style="info" %}
**Navigation:** Superstructure > Steel Girders > Tub Girder
For detailed parameter explanations, see the [Tub Girder Reference](https://docs.openbrim.org/templates/steel-tub-girder-bridge-workflow/superstructure-stg/steel-girders-stg/tub-girder-stg).
{% endhint %}
## Steps
### Step 1: Navigate to Tub Girder
Navigate to **Steel Girders > Tub Girder** in the tree view.
### Step 2: Assign Girder Layouts
Click the **three-dot icon** on the **Girder Layout** cell and set **GL1** and **GL2**.
### Step 3: Define Top Flange Width
Click the **three-dot icon** on the top flange width cell, select **Edit**, and enter **22** for both GL1 and GL2.
### Step 4: Define Station-Dependent Thicknesses
Click the **three-dot icon** on the top flange thickness cell and select **Edit (Spreadsheet)** to enter station-dependent values.
### Step 5: Set Web Depth
Enter **78** for Web Depth Projected to CL of box.
### Step 6: Define All Plate Dimensions
Use **Edit** or **Edit (Spreadsheet)** to define:
* Top flange thickness
* Web depth and thickness
* Bottom flange width and thickness
* Haunch thickness and additional haunch width
### Step 7: Assign Materials
Click the **three-dot icon** on material cells and select **A709\_50W** for:
* Top Flange Material
* Web Material
* Bottom Flange Material
### Step 8: Configure FEA Settings
Navigate to **FEA Setting** tab and assign **RigidSection** to the Rigid Section column.
Quick Tip: Haunch Thickness Definition
**Haunch Thickness** = Distance from the bottom of the deck to the bottom of the top flange.
Quick Tip: FE Model Generation
OpenBrIM automatically generates the FE model based on parametric relationships. Flanges use FeLine elements and webs use FeSurface elements.
## Verification
{% hint style="success" %}
The completed tub girder model is shown below.
{% endhint %}
---
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