> 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/substructure-ex1-sig.md).

# 6. Substructure

This section covers the substructure components that support the bridge superstructure, including piers, foundations, and piles.

{% hint style="info" %}
Substructure elements are essential for load transfer from the superstructure to the ground. Each component must be properly dimensioned for the design loads.
{% endhint %}

## Components to Model

| Component                                                                                                                      | Description                                   |
| ------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------- |
| [Pier](/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/substructure-ex1-sig/pier-ex1-sig.md)             | Pier caps and columns supporting the bearings |
| [Foundation](/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/substructure-ex1-sig/foundation-ex1-sig.md) | Rectangular footings for load distribution    |
| [Pile](/examples/steel-bridge-examples/example-steel-i-girder-bridge-ex1-sig/substructure-ex1-sig/pile-ex1-sig.md)             | Deep foundation elements beneath footings     |

## Substructure Elements

* **Pier Caps**: Horizontal members that distribute loads from bearings to columns
* **Pier Columns**: Vertical members transferring loads from caps to foundations
* **Rectangular Footings**: Spread footings for foundation support
* **Piles**: Deep foundation elements for load transfer to bearing strata

## Model Views

![Pier Cap](https://openbrim.atlassian.net/wiki/download/attachments/2101903451/image-20250117-141559.png?api=v2)

![Pier Column](https://openbrim.atlassian.net/wiki/download/attachments/2101903451/image-20250117-141720.png?api=v2)

![Foundation](https://openbrim.atlassian.net/wiki/download/attachments/2101903451/image-20250117-141829.png?api=v2)

![Complete Substructure](https://openbrim.atlassian.net/wiki/download/attachments/2101903451/image-20250117-141927.png?api=v2)


---

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