> 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-i-girder-bridge-ex1-sig.md).

# Curved Steel Plate I Girder Bridge

This example demonstrates how to model, analyze, and design a Steel I Girder Bridge using OpenBrIM.App.

![Steel I Girder Bridge Model](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/ws-guide-steeligirder.png?api=v2)

{% hint style="success" %}
**Ready to start?** Access the completed example in **New Project > Example Projects**, or follow this step-by-step guide to build from scratch.
{% endhint %}

## Bridge Overview

The finalized version of this example steel I girder bridge model can be accessed in the example projects section under the new project UI. Users have the option to start from scratch and follow a step-by-step guide to model, analyze, and design superstructure and substructure components of the bridge.

![Example Project Selection](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20250112-102329.png?api=v2)

![Bridge 3D Model](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20250112-102513.png?api=v2)

## Design Parameters

| Parameter                | Value                                                     |
| ------------------------ | --------------------------------------------------------- |
| Specification            | 2020 AASHTO LRFD Bridge Design Specification, 9th Edition |
| Structural Steel         | AASHTO M270, Grade 50 (Fy=50 ksi, Fu=65 ksi)              |
| Concrete                 | f'c=4 ksi, γ=150 pcf                                      |
| Slab Reinforcing Steel   | AASHTO M31, Grade 60 (Fy=60 ksi)                          |
| Span Length              | 160 ft - 210 ft - 160 ft                                  |
| Radius of Bridge         | 700 ft                                                    |
| Deck Width               | 40.5 ft                                                   |
| Deck Thickness           | 9 in                                                      |
| Integral Wearing Surface | 0.5 in                                                    |
| Haunch Thickness         | 4 in                                                      |
| Lane Width               | 12 ft                                                     |
| Superelevation           | 5%                                                        |

![Typical Bridge Cross-Section](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20221003-234452.png?api=v2)

![Framing Plan](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20221003-234424.png?api=v2)

![Girder Elevation](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20221003-234616.png?api=v2)

## Design Loads

| Load Type              | Value                                  |
| ---------------------- | -------------------------------------- |
| Future Wearing Surface | 30 psf                                 |
| SIP                    | 15 psf                                 |
| Live Load              | HL-93 Design Vehicle                   |
| Fatigue                | 75-year life, ADTTsl = 1000 trucks/day |

![Deck Placement Sequence](https://openbrim.atlassian.net/wiki/download/attachments/2101575802/image-20221003-234729.png?api=v2)

## Workflow Steps

Follow these 16 steps to complete the bridge design:

<table><thead><tr><th width="82">Step</th><th width="287">Section</th><th>Description</th></tr></thead><tbody><tr><td>1</td><td><a href="/pages/PF0lg2Y0QXOZnymTqeZX">Modeling on OpenBrIM.App</a></td><td>Create new project</td></tr><tr><td>2</td><td><a href="/pages/PwDMQYTAZJSpUlWE2qkj">Bridge Geometry</a></td><td>Define alignment, supports, girder layout</td></tr><tr><td>3</td><td><a href="/pages/XFL9iZtRy5eYQsX9EPJr">Properties</a></td><td>Define materials, rebars, sections</td></tr><tr><td>4</td><td><a href="/pages/BLbj7mXDhOCxzblylpcp">Superstructure</a></td><td>Model bearings, girders, deck</td></tr><tr><td>5</td><td><a href="/pages/SEFMEppHNoVNFwMCExmW">Superstructure Attachments</a></td><td>Add barriers, roadway</td></tr><tr><td>6</td><td><a href="/pages/NdhfYoQjndaS4yhDDZyI">Substructure</a></td><td>Model piers, foundations, piles</td></tr><tr><td>7</td><td><a href="/pages/9h43Q5mswEe0nGQsanLN">Construction</a></td><td>Define construction stages</td></tr><tr><td>8</td><td><a href="/pages/4NJ3NrPOGgThy4g9Bemy">Loading</a></td><td>Apply all load types</td></tr><tr><td>9</td><td><a href="/pages/PdRLdj6upyiKNe4af2DC">Combinations</a></td><td>Set up load combinations</td></tr><tr><td>10</td><td><a href="/pages/G2TEkN8fpgKHutdVFW3V">Templates</a></td><td>Configure code check templates</td></tr><tr><td>11</td><td><a href="/pages/IWdzQtkClnvKT69MdD4I">Superstructure Code Checks</a></td><td>Run superstructure design checks</td></tr><tr><td>12</td><td><a href="/pages/SwosAFjFmRR2woWzpTGA">Substructure Code Checks</a></td><td>Run substructure design checks</td></tr><tr><td>13</td><td><a href="/pages/VeracI55h4XNbZBgGRno">Load Rating</a></td><td>Perform load rating</td></tr><tr><td>14</td><td><a href="/pages/HgH7iCTjvZabjqBohoWf">Reports</a></td><td>Generate output reports</td></tr><tr><td>15</td><td><a href="/pages/mIoZxCsXPhkPzismvMB9">Design Summary</a></td><td>Review final design</td></tr><tr><td>16</td><td><a href="/pages/315qCHiVYq3qLmbTZX7b">FEA Results</a></td><td>Analyze results</td></tr></tbody></table>

## Capabilities

### 3D Modeling

* Generate parametric 3D model with substructure and superstructure
* Generate parametric 2D drawings

### Finite Element Analysis

* Create parametric FEA model
* Time-dependent staged construction analysis
* Influence surface-based live load analysis
* Creep and shrinkage per CEB-FIP 1990

### Loading

* Wind load on structure (AASHTO) from various attack angles
* Wind load on live load
* Influence surface-based braking/centrifugal/live loads (HL93, Legal Truck, Permit Trucks, custom)
* Temperature loads
* Surface/Line/Point loads on different structural elements
* Tendon stressing for substructure components

### Staged Construction

* Girder erection sequence
* Deck pouring sequence (transverse and longitudinal)
* Deconstruct deck/girder/substructure/barrier for rehabilitation
* Add/remove temporary supports
* Non-composite and composite states of girders
* Short-term and long-term modulus of elasticity override

### Analysis Results

* Incremental and cumulative stage results
* Deflection visualization (graphical and spreadsheet)
* Combination results for various limit states
* Composite results at center of gravity
* Stress distributions
* Critical vehicle location visualization

### Design (AASHTO 9th Edition)

Components supported:

* Steel I Girder
* Splices
* Cross Frames
* Cross Frame Gusset Plates
* Shear Studs
* Pier Caps
* Pier Columns
* Pier Footings
* Piles
* Drilled Shafts

### Load Rating

* Per AASHTO 9th Edition and Manual for Bridge Evaluation

### Reports

* Camber Diagram
* Quantity Report
* Seat Elevation Table
* Slab Elevation Table
* Project Inputs
* Vertical Clearance Report

### Export

* 3D model to DGN/DXF/IFC formats
* 2D drawings to DGN/DXF
* FEA model to LARSA 4D, CSI Bridge, or Midas

***

With this workflow, whenever you modify a bridge component parameter or alignment, all associated results and reports will be automatically updated and viewable within minutes. This showcases the power of parametric bridge engineering in the OpenBrIM Platform.


---

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