# 4. Superstructure

This section covers the superstructure components of the Steel I Girder Bridge, including the main load-carrying elements and their connections.

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Complete each subsection in order. The superstructure builds upon the geometry and properties defined in earlier steps.
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## Components Covered

| Component                                                                                                                                                    | Description                                              |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------- |
| [Bearings](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/bearings-ex1-sig)           | Define FEA bearing elements at support locations         |
| [Steel Girders](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/steel-girders-ex1-sig) | Create plate girder definitions with variable dimensions |
| [Stiffeners](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/stiffeners-ex1-sig)       | Add transverse stiffeners for web stability              |
| [Connections](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/connections-ex1-sig)     | Define field splices, shear studs, and gusset plates     |
| [Cross-Frames](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/cross-frames-ex1-sig)   | Model K-frame and X-frame bracing between girders        |
| [Deck](https://docs.openbrim.org/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/superstructure-ex1-sig/deck-ex1-sig)                   | Define cross-section and concrete deck properties        |

## What You'll Model

* **Bearings**: Structural connections between superstructure and substructure
* **Plate Girders**: Main longitudinal load-carrying steel members with variable flange and web dimensions
* **Stiffeners**: Transverse web stiffeners at bearing locations and intermediate points
* **Field Splices**: Bolted connections between girder segments
* **Shear Studs**: Composite action connectors between steel girders and concrete deck
* **Cross-Frames**: Lateral bracing system for load distribution and stability
* **Concrete Deck**: Bridge deck with reinforcement


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